Another new version of Ab3d.PowerToys and Ab3d.DXEngine libraries have been released.

Though this is a minor release, it still brings some amazing new improvements. For those of you that are rendering complex 3D graphics and also need to show WPF controls on top of the 3D scene, the new version of Ab3d.DXEngine brings two new great features:

1)

The performance of DirectXImage presentation type (required to show WPF controls on top of 3D scene) has been significantly improved. This was done by improving the Ab3d.DXEngine so that it can wait in a background thread until the graphics card finishes rendering the 3D scene. Then Ab3d.DXEngine invokes the code on the main thread that sends the rendered scene to the WPF composition engine. This means that the main thread does not need to wait anymore for the graphics card to complete the rendering of the 3D scene.

The most significant performance improvement of this new feature can be seen when the graphics card is rendering objects with a very big number of triangles or when using mesh instancing. In this case only a few DirectX commands issue a lot of GPU work. On the other side, when many DirectX commands are called, the performance improvement is not that big because Ab3d.DXEngine still needs to wait on the main thread until the graphics driver finishes processing the commands (DirectX Flush command needs to finish executing on the main thread). Anyway, in both cases the performance improvements (the time that you have on the main thread for your tasks) are significant. And what is best, you do not need to do anything except switching to a new version. 

2)

If you need even more performance and would also like that most of the drivers's work is done on the background thread, then you need to use DirectXOverlay presentation type. In this presentation type, the DirectX gets its own part of the screen (a hwnd handle) where it can present the rendered 3D scene when the graphics card finishes rendering. This presentation type is the fastest because the main thread is freed immediately after the Ab3d makes the last draw call by the Ab3d.DXEngine - both the driver's work and rendering are done in the background.

The problem with this presentation type is that it is impossible to render WPF controls on top of the 3D scene. Actually, WPF is not aware that the controls are hidden by the overlaid 3D scene so it will still render the controls, pass mouse events to the controls so they will be fully functional, but not visible.

The new version of Ab3d.DXEngine can solve the problem of hidden WPF controls in DirectXOverlay mode by using 2D sprites (also a new feature in this version) to show the static WPF controls (for example a TextBlock or a MouseCameraControllerInfo) or WPF controls that use Viewport3D (for example CameraAxisPanel or ViewCubeCameraController). The controls with Viewport3D are actually rendered by Ab3d.DXEngine. The trick is to render Viewport3D in a secondary DXViewportView control. This DXViewportView is created with the same DirectX device as the DXViewportView control that renders the main 3D scene. This way all DXViewportView controls can share the rendered results. For example, the secondary DXViewportView renders the CameraAxisPanel into a 2D texture and then this texture is shown on the main DXViewportView as a 2D sprite.

This can be done very easily with two new classes: WpfElementOverlay and Viewport3DObjectOverlay. What is more, the full source code of those two classes is available in the main Ab3d.DXEngine samples project.

The new version of Ab3d.DXEngine also comes with improved InstancedTextNode. This object can be used to render millions of characters. With the new version it is possible to change the individual texts and also remove some texts. For advanced users, the new version comes with a new InstancedMeshNode object that can show instanced meshes without using WPF's MeshGeometry3D (you can use any mesh derived from DXEngine's MeshBase). Also, the new version can prevent WPF's rendering thread exception (UCEERR_RENDERTHREADFAILURE) that may happen when the primary monitor has changed (for example when a laptop is connected to a docking station and uses more than one monitor; disconnecting the monitors can trigger a WPF excepton).

The Ab3d.PowerToys library also comes with a few new features and fixes. The new SphericalZoneVisual3D (and Ab3d.Meshes.SphericalZoneMesh3D) can show part of a 3Dsphere. This 3D object can be used to add a rounded end to a 3D cone or a 3D tube line. In addition, the FitIntoView method got two new overloads so you can call the method with passing a custom Rect3D (bounding box) or a custom list of 3D positions.

To see the full list of changes, check the history web pages: Ab3d.PowerToys history, Ab3d.DXEngine history.

I am also happy to inform you that the work on a new Vulkan based cross-platform rendering engine is also progressing very well. Here are two sample screenshots:

The first screenshot shows a test scene with the content of the memory dump command that shows advanced Vulkan memory management capabilities.

The second screenshot shows a simple 3D scene that is rendered in Linux and composed with Avalonia UI (Avalonia UI buttons are rendered on top of Vulkan 3D scene).

The current plan is to provide an alpha version in September 2021.

Though this year was very unusual, I am happy to conclude it by providing you additional great new features in the new version of Ab3d.PowerToys and Ab3d.DXEngine. And what is more, I am also giving you a 30% discount for any source code purchase.

In the last blog post, which was written just slightly more than one month ago, I have already mentioned that the libraries were tested with .Net 5.0 but not enough for me to release an official .Net 5.0 version. Anyway, if you checked the web page or your User Account page a few days after the release, you could see that the .Net 5.0 builds were already included in the installers. 

I also wanted to update the NuGet packages, but it is not possible to change an existing version of the NuGet packages. And I also did not want to increase the version number without any change in the code. 

Therefore I have uploaded an updated version of NuGet packages (.nupkg files) to the Downloads web page. I have also decided to provide a new version in December with some additional new features and an official .Net 5.0 support. 

So, official support for .Net 5.0 is the most significant new feature. But the new version offers much much more.

The first new feature that I would like to highlight is the new InstancedTextNode class. It can be used to render millions (!!!) of characters in any font and style. It can be also used to demonstrate the immense power of modern graphics cards. See that by yourself:

This screenshot is showing 8000 texts with different coordinates in the format "(xxx yyy zzz)". As seen in the screenshot, 94800 characters were used in the image. Impressive, isn't it! But what will you say if this screenshot is there only to make the texts easier to read and not to demonstrate the power of the new InstancedTextNode? To see the real power see the screenshot with 1 million texts (13.2 million characters):

This can easily run with 60 FPS on a modern GPU. Get the latest version and check this out by yourself. It is really amazing!

Though the previous two images used only black text, it is possible to set each text's position, orientation, size, and color. And after the text is shown, it is very easy to hide, show, move, scale and change its color. The following image shows that:

The InstancedTextNode achieves this level of performance by using DirectX object instancing and multiple textures - one texture for each character. When adding different texts to the InstancedTextNode, the code checks which characters are used in the text and when a character that was not used in any previous text is found, it renders the new character to a new texture. Then for each character in the text, it calculates a world transformation matrix and uses it for the InstanceData. Then it uses object instancing to render all instances (all appearances in all texts) of one character in one draw call. This is done for each character. Because some parts of the character textures are transparent, the InstancedTextNode uses alpha-clipping to discard the transparent pixels. This preserves the excellent performance because it avoids sorting the individual characters by their distance to the camera.

So the InstancedTextNode can be used when you need to render a lot of text. It can also be used to render just a few characters. But in this case I would still recommend using the TextBlockVisual3D object because it provides more options and is faster for rendering just a few characters - it requires one draw call to render the whole text while the InstancedTextNode requires individual draw calls for each character.

And the TextBlockVisual3D also got a few new improvements in this version. First, its Material and BackMaterial properties preserve the DiffuseMaterial instance (before new instances can be created when the properties were changed). Because the instance is now preserved, this means that you can easily assign special DXEngine's attributes to the Material and BackMaterial properties - for example, to use alpha-clipping. In the new version you can also assign a new UseSolidColorEffect DXAttribute. When UseSolidColorEffect is set to true, the text will be rendered without any lighting calculations. This can prevent dimming the text when the text does not face the lights. There is a new ImprovedTextBlockVisual3D sample available that demonstrates that and shows the benefits of using ImprovedTextBlockVisual3D in Ab3d.DXEngine.

This version also (finally) shows how to use object id bitmap. Object id bitmap is created by rendering the objects to a bitmap by setting each object's color to a unique color that represents object id. This way it is possible to get the object id from the color of each rendered pixel. The new version demonstrates that by showing how to make a rectangular selection of objects.

Because Ab3d.DXEngine can render millions of 3D lines with different display styles (line thickness, pattern, hidden lines), it is also used in some applications to show 2D lines and 2D shapes or to create a 2D shapes editor. To provide a demonstration on how this can be achieved, the new version comes with a new TwoDimensionalCamera class and 3 new samples. The TwoDimensionalCamera creates a camera that can show a 2D scene. The objects in that scene are still standard 3D objects - there the x and y coordinates represent the position in the 2D scene; the z value is usually set to 0 (but can be changed to render some lines or objects in front of or behind other lines or objects). The TwoDimensionalCamera supports moving and zooming the camera. A simple 2D lines editor sample shows how to create a line editor with snipping to positions.

When speaking of lines, there is another new feature that I want to talk about. It improves support for rendering 3D lines that are always rendered exactly to screen pixels. The previous version of Ab3d.DXEngine introduced super-sampling support that can produce very nice smooth lines. But because line coordinates are defined as float values, the lines on the screen can be rendered between screen pixels. For example, if a 1 screen pixel thick horizontal black line is rendered on a white background and if the line falls between two screen pixels, the line will appear as 2 pixels thick gray horizontal line - the black color will be distributed between 2 pixels. When rendering multiple thin horizontal and vertical lines (for example, in a grid) this may produce some unwanted effects. This can be seen because some lines appear black and sharp (rendered exactly to the screen pixels), some are gray and twice as thick (rendered between two screen pixels) and others are in between.

It was already possible to render lines that are rendered exactly to screen pixels. This can be done by setting UseGeometryShaderFor3DLines and RenderAntialiased3DLines properties on DXScene object to false. But this setting is applied to all lines. So also angled lines will be shown without any anti-aliasing. What is more, lines rendered without geometry shader can be only 1 pixel thick. Therefore this option was rarely used. 

So each rendering option provides its benefits and its drawbacks. In the previous version it was not possible to mix them in a single scene. Now, this is possible. You can set the new UseGeometryShaderFor3DLines and RenderAntialiased3DLines DXAttributes to the selected 3D lines and specify how you want to render them. So you can render the horizontal and vertical grid lines as sharp 1 screen pixel lines and all other lines as standard smooth lines. Unfortunately, there is still a small catch - you cannot use super-sampling when using 1 pixel thick non-anti-aliased lines. The problem is that when using super-sampling, the line thickness needs to be increased by the SuperSamplingFactor so that when the super-sampling texture is down-sampled, the final line thickness is correct. But without using a geometry shader, it is impossible to increase line thickness, so when down-sampling the 1 pixel thick lines will appear 1/2 or 1/4 thinner. Anyway, you can still use multi-sampling. In the future, I plan to solve this problem by providing options to snap 3D lines to screen pixels.

And one final new feature that you may also consider important: the new version can prevent the UCEERR_RENDERTHREADFAILURE exception in WPF's render thread that can crash the whole application. That exception can sometimes occur when the primary monitor is changed. For example, when a laptop is connected to a secondary monitor with a duplicate screen option and then the laptop is closed. In this case, the secondary monitor becomes the primary monitor. It looks like there is a bug in the WPF that may crash the application. But I was able to prevent that by detecting the primary monitor's change and then recreating some of the internal objects. This seems to prevent the crash.

So, plenty of reasons to be excited about the new version. As always, start the new samples project and check the NEW and UP icons to see new and updated samples. For more details read the change log - here: https://www.ab4d.com/DXEngine-history.aspx and here: https://www.ab4d.com/PowerToys-history.aspx

And if you were wondering what is going on behind the scenes and wanted to peek into the Ab3d.DXEngine and Ab3d.PowerToys source code, now is the best time to purchase the source code. Just go to the purchase web page. The 30% discount is already applied to all source code items.

I wish you a nice and peaceful conclusion to this year. And also a few pleasant surprises (I hope this new version is one of them). And of course, happy and successful 2021!

I am happy to inform you that new versions of Ab3d.DXEngine and Ab3d.PowerToys have been released.

By the new version numbers you may think that this is just a smaller update, but I am sure that the content that follows will persuade you that this is another big and great update that can significantly improve the value of your application and provide you with some great new tools for your work with 3D graphics.

Here are the highlights of the new version:

• Added support for super-sampling provides rendering of super-smooth 3D lines and better rendering of details.
• Added support for creating edge lines and improved support for rendering object outlines. This can render the scene in a way that is standard for CAD programs.
• Improved support for rendering the same 3D scene with different DXViewportView (each with different camera and render settings).
• Significantly improved the performance of the DXEngine's update step.
• Simplified hierarchical organization of Visual3D objects with using ContentVisual3D that defines IsVisible property and now also supports showing and hiding Visual3D objects in Children collection. This also greatly improves the performance of showing and hiding Visual3D objects.
• Improved ViewCubeCameraController - the new version supports clicking on cube edges and corners. 
• Added custom wpf3d file format that can store WPF 3D scene. The full source code to read and write wpf3d file is available with the samples project. This way the code can be adjusted to your needs.
• Many other improvements and fixes.

The following image demonstrates the first two highlights:

The first step in creating the image above was to import an aircraft engine model from a file. Then a new EdgeLinesFactory.AddEdgeLinePositions method was called. This method analyses the 3D model and creates edge lines if the angle between two adjacent triangles is bigger than the specified angle. This way it is possible to get much more accurate edge lines than by showing the wireframe of the model. The problem with showing the wireframe is that it shows lines around all triangles even if they lay on the same plane (for example, a diagonal line on cube sides). After having the edge lines, we can show the lower part of the image.

But as the upper part of the image shows, with the new version of Ab3d.DXEngine it is possible to create a superior and much more professional looking result. 

The first thing that can be done with the Ab3d.DXEngine is to set line depth bias. This moves the 3D lines towards the camera and away from the solid model so it cannot occlude the lines when they occupy the same 3D space. In the upper image, this can be seen in the lower right part of the image where the line thickness changes because the solid model occludes the lines. The new version of Ab3d.DXEngine also improves using line depth by preventing the lines from being moved away from the 3D model (when using a perspective camera). This simplifies setting the correct line depth bias.

The second feature that improves appearance in the image above is the object's outline. This renders a thicker line around 3D models. The line is also drawn on places where there are no edge lines - for example, when a curved model ends - in the image above this is just below the "objects outlines" text.

But the most significant improvement of using the new Ab3d.DXEngine is the use of super-sampling that can produce super-smooth 3D lines. In the last few months a lot of effort was put into improving the quality of 3D lines. I first tried to create smooth lines by adjusting the alpha values on pixels near the edge of the line. This slightly improved line quality. But because of using transparency on the edges, this could create artifacts if lines were not rendered in the correct order. After some other tests, it finally became apparent that using super-sampling can provide the best results. Click here to see a screenshot from a line quality testing sample.

Super-sampling (SSAA) is an anti-aliasing technique where the 3D scene is rendered to a bigger image and then down-sampled to the final image. For example, 4x SSAA means that the rendering is performed to an image that has twice the width and twice the height of the final image (has 4 times the number of pixels). The image quality can be further improved when down-sampling uses a special filter that reads samples in a slightly rotated pattern and uses different weights on the read samples. As the image above shows, this can produce highly superior results.

The difference between super-sampling and multi-sampling is that with multi-sampling, the number of pixel shader invocations is the same as with no multi-sampling. In this case, the color that the pixel shader returns is saved to multiple pixels (samples). At the end of rendering the multi-sampled texture is resolved so that all the samples are used to produce the final pixel color. This can significantly improve edge aliasing. But because there were no more pixel shader invocations, this does not produce an image with more details. For example, 4x MSAA requires 4 times the memory because each pixel shader result is shared with 4 pixels, but the number of pixel shader invocations is the same as when no multi-sampling is used. This is the main difference compared to super-sampling. There the scene is rendered to a bigger texture. This means that 4x SSAA requires four times the memory and also four times the number of pixel shader invocations. As seen in the image above, using 4x MSAA can significantly improve line quality compared to using no multi-sampling. But using 8x MSAA does not provide any more significant quality improvement. But using super-sampling can provide much better results.

Because of much higher memory usage and the number of pixel shader invocations, using super-sampling comes with high costs. This may not provide a significant difference on a high-end graphics card, but on an integrated graphics card, the slow-down may be noticeable. Though the max supported super-sampling count is 64 (rendering to 8 times width and height), the high super-sampling count should be avoided in most cases. You should also be careful because the maximum texture width and height in DirectX 11 is 16384. For example, this limit is reached on a 4k monitor when 16x SSAA is used. The Ab3d.DXEngine knows about this limitation and can dynamically reduce the super-sampling count to stay below this limit. Also, because SSAA can be combined with multi-sampling (MSAA), the recommended setting to achieve super-smooth lines is to use 4x SSAA with 4x MSAA (this was also used to produce the image above). To see the memory requirements of the various settings, open the diagnostics window that now shows the required amount of memory. The diagnostics window can be opened in the samples project by clicking on the Diagnostics button. In your application you can show the diagnostics window by using the DXEngineSnoop tool and attaching to your application (more info on Ab3d.DXEngine diagnostics web page).

Also note, that because of super-sampling, the settings for standard GraphicProfiles have changed:

• NormalQualityHardwareRendering is the same as before - using 4x MSAA and no super-sampling.
• HighQualityHardwareRendering is now using 4x MSAA and 4x SSAA (before 8x MSAA was used - so now twice the memory is required and 4 times the number of pixel shaders invocations).
• UltraQualityHardwareRendering is now using 2x MSAA and 16x SSAA (before 8x MSAA was used - so four times the memory is required and 16 times the number of pixel shaders invocations).

This is important because if you are using HighQualityHardwareRendering or UltraQualityHardwareRendering you should not be surprised if the new version will be slower than the previous version. To compare the performance, use the same settings, or keep in mind that the new super-sampling requires much more work behind the scene.

To summarize, if you show 3D lines, then the superior line quality should justify the costs of super-sampling - especially using 4x SSAA with 4x MSAA. But my recommendation is that you still use it wisely. The easiest option is that your application provides a setting that can change the graphics quality. This way users on slower computers can disable or reduce the super-sampling and still enjoy in great application performance but with reduces quality. To provide a suitable default quality setting, you may check the amount of graphics card memory, display's size and monitor DPI setting (see source code of SystemInfo class for a sample on how to get GPU memory size; you can get DPI settings by a new static GetDpiScale method on DXViewportView).

Ok, we have covered the first two points in the highlights list. Let's move on. The most obvious way to hide some of the 3D objects is to remove them from the 3D scene. But when this is done with Ab3d.DXEngine (and if the objects are not added back to the scene in the same frame), then the DirectX resources for the removed objects are disposed and removed from the graphics card. This also means then when those objects are added back to the scene, then the DirectX resources will need to be regenerated and sent to the graphics card.

Ab3d.DXEngine tried to solve this with improved support for IsVisible property that was available with the BaseVisual3D class from Ab3d.PowerToys library. In this case when the IsVisible property was set to false, then all the DirectX resources are preserved, but the rendering of the object is skipped in the rendering loop. This means that when the IsVisible property was set back to true, the object can be shown instantly as no resources need to be created.

Because all Visual3D objects from Ab3d.PowerToys are derived from that class, they all received that improved support. With using ContentVisual3D (also derived from BaseVisual3D) it was also possible to show and hide any GeometryModel3D or Model3DGroup objects that was set to ContentVisual3D.Content property. But if you want to show or hide a hierarchy of Visual3D objects, then you still needed to remove those objects from the scene and then add them back. This was finally solved with the new version of Ab3d.PowerToys and Ab3d.DXEngine that now also fully supports showing and hiding Visual3D objects from ContentVisual3D.Children collection.

What is more, because ContentVisual3D now defines a new ChildrenChanged event, it is much easier (and requires much less CPU time) for the Ab3d.DXEngine to check the changes in the Children collection. This makes the ContentVisual3D class a much more appropriate object to hold other 3D objects than the ModelVisual3D class. To simplify the usage of ContentVisual3D, there is also a new CreateContentVisual3D extension method that can simplify creating ContentVisual3D objects from any GeometryModel3D or Model3DGroup objects.

So using ContentVisual3D with Ab3d.DXEngine can reduce the time in the update phase (in this phase the objects are checked for changes and the RenderingQueues are updated). The new version also significantly reduces update time in some other very common cases. One such case is when an object's transformation is changed. Now, this is processed much faster and in a 3D scene with many objects can provide significantly lower update times. Also, changing individual positions or triangle indices in MeshGeometry3D now takes the faster update path.

Another great new feature is improved support for having different views of the same 3D scene. Each view can have a different camera and use different rendering settings. Before, this was possible only by creating new Viewport3D objects and duplicating the Visual3D objects in each Viewport3D (the MeshGeometry3D and Model3D objects can be shared). What is more, it was not possible to use the same SceneNode objects in multiple views. With the new version of Ab3d.DXEngine it is possible to create a DXViewportView by passing a master DXViewportView as a constructor parameter. This creates a child DXViewportView that uses the same 3D scene (DXScene object) but can provide its own camera and its own rendering settings (rendering scene as wireframe, rendering just some objects of the scene, or using some special effects on some views).

The new samples projects for Ab3d.PowerToys library also comes with a new Wpf3DFile class. This class provides the full source code to read and write wpf3d files. wpf3d is a custom binary file format that can save WPF 3D scene. It can save the hierarchy of Model3D objects with their materials. It can also save model metadata with a preview bitmap. This way you can quickly read the metadata and show that to the user. The following screenshot is showing a sample with four possible wpf3d files:

The main use case for using this file format is to convert existing files in other file formats (for example fbx) into wpf3d files. Then you can simply use the Wpf3DFile class to read the files and do not need to distribute the native Assimp library with your application anymore. You can also change the Wpf3DFile source code and store some additional data relevant to you into the file. You may also want to encrypt the data, use any other file extension (not .wpf3d), or make any other change to the file structure.

The last feature that I would like to mention is an improvement to the ViewCubeCameraController.  Because the ViewCubeCameraController provides such an intuitive way to show the orientation of the camera, it is used by many users. Therefore, you will be happy to hear that the new version of ViewCubeCameraController supports clicking on the cube's edges or corners to rotate the camera. For users this is a very nice and useful feature. And what is the best - you just need to update to the latest version of Ab3d.PowerToys and do not need to change anything in your core to provide this new feature.

As always, there are many other new features and fixes. The best way to check them is to see them in action with new samples projects that come with both libraries - start the samples and pay attention to the NEW and UP icons in the samples list on the left (the UP icon also provides a tooltip of what is changed). You can also read the full change log on Ab3d.PowerToys history and Ab3d.DXEngine history.

You can get the new versions from new NuGet packages. If you have a valid updates subscription, you can download new installers from your User Account web page. To just test the new version you can also download the new evaluation version from the Downloads page.

Let me conclude with some future plans. 

The .Net 5 was just released two days ago (on 10 November). I did some testing with .Net 5 RC versions and both Ab3d.PowerToys and Ab3d.DXEngine compiled and ran without any problems there. But I run out of time to thoroughly test and update the release process to provide an official .Net 5 versions of the assemblies. But this will be done in the near future. So stay tuned for news about that.

And finally, a sneak peek of a more distanced future:

This screenshot shows v0.2 of the new Vulkan based rendering engine. The screenshot shows it can run on Linux. There is a Rider IDE in the background. See great performance figures in the window title - note that this is running on an older system with i7 3770 @ 3.4 GHz and NVIDIA 970 GTX. The new rendering engine is being written from the ground up and will use the latest .Net features and all the know-how from Ab3d.PowerToys and Ab3d.DXEngine.

It is hard to say when the first official version of the new engine will be available. Using Vulkan API and different platforms is much more challenging than using DirectX 11 and Windows. Therefore, if you would like to speed up the development, participate in the development by providing feedback and testing on other platforms or would just like to share your wishes and ideas, you are most welcome to contact me.

As always, the goal is to provide you an awesome cross-platform rendering engine for technical, scientific and CAD-like 3D visualizations.

I am proud to inform you that a new major release of the Ab3d.DXEngine has been released. There is also a new minor version of Ab3d.PowerToys.

Let's start with a question: what makes a rendering engine faster? The answer is simple: a faster rendering engine will render the 3D scene quicker and achieve higher frames per second. This can be achieved in two ways. The first option is to provide special rendering techniques to the end-user that can optimize the rendering (for example, object instancing). The second option is to organize the data for the 3D scene so that it can be sent to the graphics card as quickly as possible and in a way that allows the graphics card to render the scene the most optimally.

This part of the job is done internally by the DXEngine. This process was already highly optimized for CPU, memory access and can be executed using multiple threads. Still, a 3D scene with a few thousand objects may require a few milliseconds of CPU time to render. In this case, a rendering engine written in C++ or another low-level language may be faster because its code can be better optimized.

But with the introduction of DirectX commands caching in the new version of Ab3d.DXEngine, this advantage of low-level languages is significantly reduced. In case when only camera or lights are changed (the majority of cases in a typical business or scientific 3D application), then the new version of Ab3d.DXEngine can render the new frame with only updating the camera and lights data and then "instructing" the graphics card to re-render the new frame with using the DirectX commands that were recorded in one of the previous frames. This requires so little code to be executed on the CPU, that even if the engine were written in C++, the performance difference would not be noticeable.

Therefore I would like to conclude the first part of this post with a statement that in cases when DirectX commands caching can be used (in a typical business 3D application this is most of the cases) the Ab3d.DXEngine is as fast as if it would be written in C++. 

Let me show you that in action:

As seen from this screenshot, in case of rendering 160.000 individual 3D objects, the time required to send all that data to the graphics card is only 0.14 ms (see DrawRenderTime which shows time to execute 160.000 draw calls with all required state changes). This way, it would be possible to achieve almost 3000 FPS. When the command list caching would be disabled, then the DrawRenderTime would be around 16 ms. This is still a fantastic result and can be achieved using multi-threading and many other optimizations.

Another area that received some great new features is rendering transparent objects. Rendering transparent objects can be hard in 3D graphics. The reason for that is that when a transparent object is rendered, the colors of the already rendered objects are blended with the color of the transparent object. This means that if we want to see the objects through transparent objects, they need to be rendered before the transparent object. Usually (when the objects are not self-intersecting), this can be solved with sorting the objects so that the objects that are farther away from the camera are rendered first. To help you with sorting, you can use the TransparencySorter class from the Ab3d.PowerToys library. But this class work only for WPF 3D objects. What is more, sorting WPF 3D objects can be a very slow process and in case of complex hierarchy, it may not be possible to sort all the objects correctly.

The new version of Ab3d.DXEngine provides a better way of sorting transparent objects. With setting the DXScene.IsTransparencySortingEnabled property to true (by default it is set to false to make the engine work as in the previous version), the engine automatically sorts all the objects in the TransparentRenderingQueue. Because the objects there are defined in a flat queue, there is no problem with the hierarchical organization of objects. Also, sorting is highly optimized and uses multi-threading, so it is much faster than TransparencySorter. And finally, the DXEngine's SceneNodes can also be sorted in this way.

Another new feature regarding transparent objects is the added support for alpha-clipping and alpha-to-coverage. Those two techniques can be used to render textures that have opaque and also transparent pixels (for example, text with a transparent background or threes). An advantage of those two techniques is that they do not require the objects to be sorted by camera distance. But they can produce some artifacts on the areas where the transparent part of the texture is transitioned to the opaque part. If this transition is small, then the results can be very good. In the case of using alpha-clipping, the user can select an alpha clip threshold - this is a value that specifies at which alpha value the pixels are clipped. When using alpha-to-coverage, it is possible to use MSAA (multi-sample anti-aliasing) to provide a more accurate level of transparency with making some sub-pixel samples transparent and some opaque. See the comments in the new sample for more information.

There are also improvements in how textures are loaded. First, all textures that are created from WPF BitmapImage objects are checked if they actually contain transparent pixels. In the previous version, only the file format was checked and if it supported transparency, then the texture was considered transparent. In this case, the object that used that texture was put into the TransparentRenderingQueue - requiring alpha blending (more GPU memory transfer), transparency sorting and having no rendering optimizations. In the version, the DXEngine "knows" if the texture does not have any transparent pixels so its object can be put into the StandardGeometryRenderingQueue. This way, it gets support for multi-threaded rendering and DirectX commands caching.

The last new feature related to transparency is that the TextureLoader.LoadShaderResourceView method has been significantly improved. The method loads a texture into a DirectX resource and now also sets a new TextureInfo class that describes the loaded texture: image size, dpi, format, has transparent pixels. That information can help you correctly set the properties in the StandardMaterial or any other material that is showing the texture.

There are also some other great new features. Let me quickly mention some of them.

Object instancing also received a few improvements. The first improvement is that it is now possible to quickly hide (discard) some instances when setting their alpha color to 0. In the previous version, such instances were still rendered - they were not visible because of alpha value 0, but their depth values were still written and therefore this prevented rendering of all objects behind them. So in the previous version, you needed to re-create the InstancesData array with removing some items from the array.

The next new feature is that now you can render instanced objects with a single color without any light shading. Another instancing improvement is that it is now possible to specify the size of each instance in screen-space units. This means that even when you zoom in or out, the size of the instances on the screen will remain the same (the size calculations are done on the graphics card).

Another performance-related improvement is that now multi-threaded rendering is also supported for 3D lines. Before, it was supported only for standard and opaque 3D objects. It is still better to combine many 3D lines into a single 3D line object (for example, MultiLineVisual3D or even better ScreenSpaceLineNode), but if you happen to have many individual 3D line objects, then the new version could now render at more then 4-times the speed.

If you are an advanced DXEngine user, you will be interested in that the GeometryRenderingQueue has been split into 4 different rendering queues: 

• ComplexGeometryRenderingQueue - used for instanced objects and very complex meshes (with more than 100.000 triangle indices or 20.000 lines) - the idea is to send such objects to GPU as soon as possible,
• StandardGeometryRenderingQueue - highly optimized for rendering standard 3D objects - supports multi-threading and command list caching,
• OtherGeometryRenderingQueue - used for other 3D objects with non-standard effects,
• LineGeometryRenderingQueue - used for opaque and solid color 3D lines - support multi-threading),

The old GeometryRenderingQueue is still defined in the DXScene class. But it is marked as obsolete and points to the OtherGeometryRenderingQueue. If you are using the GeometryRenderingQueue, please change that to any of the 4 new rendering queues instead.

Advanced users will be also happy to hear that there are some interesting improvements in the Diagnostics project that is also used in the DXEngineSnoop tool (see also Diagnostics Guide). Now you can render an object-id bitmap of the 3D scene - there the colors in the bitmap represent the ids of the rendered objects. You can also disable and enable rendering of some RenderingQueues and RenderingSteps. With those new features, you can diagnose some low-level rendering problems and get some additional understanding of how the rendering engine works.

As always, there are many other new features, improvements and bug fixes. This is also true for Ab3d.PowerToys. To get the full list of changes see Ab3d.DXEngine versions history and Ab3d.PowerToys versions history.

From the number of support requests, I have seen that the corona crises have significantly slowed down the development worldwide. This lasted for around a month and a half. Then suddenly, there was a burst of activity that highly exceeded the time before the pandemic. So it looks like during the quarantine, you had time to gather many great new ideas. So, when the development started again, you wanted to try them right away. I was pleased to see that. I hope that the newly published versions will allow you to realize your ideas even more quickly and have better results.

I am happy to inform you that new versions of Ab3d.PowerToys and Ab3d.DXEngine libraries have been published.

The new libraries bring many new features and improvements. But probably the most important is that both libraries now support .NET Core 3.1 (released on 3rd December) - see more: https://devblogs.microsoft.com/dotnet/announcing-net-core-3-1/. This version of .Net is a long-term supported (LTS) release. Therefore it is recommended to use that version instead of .NET Core 3.0.

Let's go back to the new features.

Probably the most interesting new feature is support for planar shadows. Shadows are very important to give the viewer a real sense of depth and distances between objects. Consider the following two images that show the differences.

The first image is showing a Ducks lake sample - there a VarianceShadowRenderingProvider is used to provide nice soft shadows that add a much more realistic feeling where it is very clearly seen that the ducks are actually swimming in the lake. In the right part of the image the ducks might also be floating in the air.

The image below is showing a new sample that uses a new PlanarShadowRenderingProvider. Again, in the part with shadows it is very easy to see the distance between the spheres and the plane. But in the right side without shadows this information is totally lost.

What are the differences between those two shadow rendering techniques?

The VarianceShadowRenderingProvider uses a variance shadow mapping algorithm that can render nice soft shadows with minimal artifacts (compared to some other shadow rendering techniques). The shadows can be rendered to all 3D objects.

In this algorithm, the whole 3D scene is rendered from the light's position into a special texture - a shadow map. The values in this texture do not represent object colors but float values that describe distances from the light. Because the shadow information for the whole 3D scene (not only for visible part) is written into one texture, the resolution of the shadow depends on the size of the shadow texture and the size of the 3D scene. Sometimes it is desirable to have a more blurry shadow. But other times, especially in technical applications, users want to have more precise shadows. To increase the shadow resolution, the shadow texture size needs to be increased (with ShadowMapSize property), or the size of the whole 3D scene needs to be decreased. Increasing the shadow map size can significantly reduce performance. Also, decreasing the size of the 3D scene is not always possible. So this shadow rendering is not ideal for all the cases (there is actually no such technique except ray tracing).

On the other hand, the planar shadow rendering always renders perfectly sharp shadows without any loss of details. But as its name suggests, the shadows can be rendered only to a 3D plane. This techinque is also faster to render. There the shadows are rendered with applying a shadow matrix transformation to all objects. This matrix flattens all the objects so that they have no height and become only 2D shapes that represent the shadows. Those shapes are then rendered as 3D objects on top of the 3D plane.

Disadvantages of planar shadows are that they can be rendered only to 3D planes, they cannot have soft edges, shadows are also rendered for objects behind the plane or point light, some objects that lie on the plane or are very close to the plane may get invalid shadow (too wide). But still, they are an excellent choice for many scenarios.

Anyway, you as a user now have more choice regarding the shadow rendering. What is more, the planar shadows can be also rendered with WPF 3D rendering and do not require Ab3d.DXEngine.

In this case the new PlanarShadowMeshCreator class from Ab3d.PowerToys can generate the 3D mesh that can be rendered as a planar shadow. This class can even clip the shadow to the edges of the 3D plane. But the mesh generation is 100% done on the CPU. And each time the light or the objects are changed, the whole shadow mesh needs to be regenerated. When the 3D scene is complex, this shadow mesh generation can present a performance problem. What is more, WPF 3D cannot render semi-transparent shadows correctly. The problem is that the shadow is darker and less transparent in the areas where multiple parts of the 3D objects are rendered. This means that with WPF 3D only opaque shadows can be correctly rendered. But still, it is possible to significantly improve the visual appearance of some 3D scenes by adding planar shadows without any transparency.

To correctly render the semi-transparent shadows and to avoid the slow 3D mesh generation on the CPU, it is possible to use the PlanarShadowRenderingProvider from Ab3d.DXEngine library. It provides full hardware acceleration for rendering planar shadows and uses the stencil buffer to clip the shadow to the edges of the plane and to prevent semi-transparent shadow artifacts (it ensures that each shadow pixel is rendered only once).

Another great new feature of the Ab3d.DXEngine library that was requested from some users is the ability to render 3D lines with different start and end colors. In this case, the line color is interpolated from the start to the end color. It is also possible to specify color's alpha values so that the line slowly fades away (its alpha value goes from 1 to 0). This is very useful for showing trails of moving 3D objects (for example orbits of planets). The following image shows a screenshot from a simple sample that demonstrates that new feature:

Ab3d.DXEngine can already render huge point clouds with hundreds of millions of points. To optimize rendering in such extreme cases, a OptimizedPointMesh can be used. This object can significantly reduce the number of points that need to be rendered. But until now all the points need to be in the same color. With the new version of Ab3d.DXEngine it is possible to specify a different color for each point.

The new version also improves the mouse rotation and movement when showing point clouds. This is done with new methods that return the 3D position that is closest to the mouse position. This way it is possible to use camera rotation around mouse position when showing point cloud data. Also, because the distance from the camera to the position under the mouse can be correctly calculated, the mouse movement is more precise.

The last new feature in Ab3d.DXEngine that I would like to mention here is that with the new version of the library it is possible to recover from rare cases when the DirectX device is removed or reset by the OS. This happens when the graphics driver is updated while the application is running. This can also happen in case when there is some problem with the driver (very rare). Note that this does not happen when the operating system is restored from sleep or hibernation or when the window is minimized and then opened again.

To handle the DirectX device removal, there is a new DeviceRemoved event in the DXScene class. In the event handler the application can save the current state of the 3D scene, then dispose the current DXViewportView and other 3D objects and finally create a new DXViewportView and recreate the 3D scene from the saved data. There is a simple sample that demonstrates that.

Regarding the new Ab3d.PowerToys library I would like to mention that now it works with a new Assimp library v5.0. This provides improved support for importing 3D models from many file formats. What is more, the Ab3d.PowerToys has improved skeletal (skinned) animation that can animate 3D objects with a more complex hierarchy of bones.

Another nice new feature is that the ViewCubeCameraController can now show different bitmaps for selected planes. This gives users a nice indication that they can click on the plane to rotate the camera to see the 3D scene from the selected angle.

And finally, I would like to mention two new samples that come with Ab3d.PowerToys.

The first one is called "Basic WPF 3D objects tutorial". I have seen many users that wanted to create an application with 3D graphics and just jumped in and started using the Ab3d.PowerToys library. They may be able to do some complicated things because some powerful features of the library are very easy to be used. But sometimes, when it comes to some relatively simple tasks, they are stuck because they do not know the basics of the WPF 3D objects. This new sample should help such users to be quickly back on track.

Another new sample is called "Standard WPF hit testing". The reasons why I wrote this sample are very similar to the reasons mentioned before. When it comes to 3D hit testing, many users thought that the only way to do that is to use the EventManager3D. The reason for that was that the samples that come with Ab3d.PowerToys were only showing the features of the library and therefore only the usage of EventManager3D was mentioned. So many users were not aware that there is also a low-level way to do the 3D hit testing. In this way, the user can get the closest or all the 3D objects that are behind some specified 2D position (for example mouse position). This approach is actually more useful and can be used in more cases, especially in situations when there are many possible hit objects and when the objects are dynamically added and removed. EventManger3D is more suited for simple 3D scenes where the number of 3D objects is low and does not change a lot.

As always, there are many other new features and improvements. For the full list of changes see the https://www.ab4d.com/DXEngine-history.aspx and https://www.ab4d.com/PowerToys-history.aspx.

At this point, I would also like to tell you something about an exciting new feature that is already in development and is planned for the next version. It is called "reused DirectX command lists". With technical 3D applications it is very usual that the 3D scene is mostly static and many times only the camera is changing. With DirectX 11 it is possible to render such 3D scenes extremely fast with almost no CPU overhead. This is done with recording a command list that contains all the DirectX commands that are required to render one 3D scene. After the command list is generated, we can reuse it for other frames. So if only the camera is changed, then we just send new camera information to the graphics card and then instruct it to render the same command list as before. This can be done with almost no CPU time spent. The results are stunning. See the following screenshot:

The arrow is pointing to the area that is showing the CPU time to render the scene. In this case, the CPU time to render 160.000 individual boxes (without using instancing but with creating one draw call for each object) is only 0.10 ms. Now compare that with what is possible to achieve with standard rendering process and with full multi-threading - see the screenshot from https://www.ab4d.com/images/DXEngineGallery/DXEngine-Multi-threaded-rendering.png

There you can see that the CPU time to render the scene is almost 15 ms. This is still an incredible achievement, but compared to 0.10 ms it is a lot.

There are some complex challenges that need to be solved before reused command lists can be used in a generic purpose rendering engine as Ab3d.DXEngine is. As you can see, a special demo version is already running. A more generic version will be ready for the next release, so stay tuned.

As it was already announced in the previous blog post, the new versions of Ab3d.PowerToys and Ab3d.DXEngine are available through multiple sources:

• NuGet packages (https://www.nuget.org/packages/Ab3d.PowerToys/ and https://www.nuget.org/packages/Ab3d.DXEngine/). This distribution includes assemblies for .NET Framework 4.0 and 4.5+ and for .NET Core 3.1. The same dll (assembly) is used for both evaluation and commercial usage. By default, the evaluation license is started. The commercial license can be activated with calling the SetLicense method and providing the license information. In the near future, it will be possible to get the license parameters from the Users Account web page. Until then, please contact us for the parameters.
• The commercial version installer can be downloaded from the User Account web page. Because the old licensing system that uses license.licx files cannot be used in .NET Core, this distribution contains only assemblies for .NET Framework 4.0 and 4.5+.
• The evaluation installer can be downloaded from Downloads web page - https://www.ab4d.com/Downloads.aspx. Also contains only assemblies for .NET Framework 4.0 and 4.5+.

I am pleased to inform you that some significant changes to our libraries have happened.

Everything started with the announcement that .NET Core 3 will support WPF and WinForms application. That meant that Microsoft would finally upgrade its frameworks that are used to create most of the desktop applications.

My first port to the beta version of the .NET Core 3 was very promising and it looked like that it will be easy to provide day-zero support for the new framework. But when the release day approached and when some additional tests were done, then some problems begin to emerge. Though the main functionality of the Ab3d.PowerToys and Ab3d.DXEngine libraries was ported without any problems, the existing licensing mechanism did not work with the new compiler. 

Our libraries use the standard .Net licensing mechanism that use license.licx files - in case when this file is present, the .Net compiler calls the licensing code inside the library during the compilation of the project. The licensing code can generate a run-time license key that is embedded into the project. This then allows to run the project on cumputers where the library is not installed. The problem was that the compiler for .NET Core 3 did not call the licensing code. This meant that it was not possible to use the existing licensing mechanism to provide commercial licenses. What is more, some tools (obfuscator) also did not fully support .NET Core 3 assemblies at the time of the release.

Therefore a new licensing mechanism was needed. Besides the support for .NET Core 3, one of the main goals of the new licensing was also to allow distribution with NuGet (without private repositories). This required that a single dll should be used for the evaluation and for the commercial version.

If you have checked our web site recently, you may have noticed that it was already possible to download beta and release candidate versions of the Ab3d.PowerToys and Abd3.DXEngine. The new libraries support .NET Core 3 and have a new licensing mechanism. And today I am announcing that final versions of both libraries were released on NuGet.

Let me quickly describe the new licensing mechanism. It is super easy to use. When the library is used for the first time, a "Start evaluation" dialog is shown. This allows the user to start a 60-day evaluation of the library. In evaluation mode, all the features of the library can be used. The differences between running in evaluation and commercial mode are that in evaluation mode sometimes an evaluation watermark is shown and a dialog to show remaining evaluation days is shown once per day.

To activate a commercial version of the library, you do not need to change the dll, but you simply need to call a SetLicense method and pass a company name, license type and license text as parameters. For example, to activate Ab3d.PowerToys library, you need to add the following line to your project (it should be called before any Ab3d.PowerToys code is used):

Ab3d.Licensing.PowerToys.LicenseHelper.SetLicense(licenseOwner: "[CompanyName]",
                                                  licenseType: "[LicenseType]",
                                                  license: "[LicenseText]");

The same method can also be used to extend the evaluation period.

Note that the license text is not the same as the license key that was used until now. The difference is that the license text also need to include information until when the updates for the library are available. This is needed because everybody has access to the latest version of the libraries. So the licensing code needs to prevent using a commercial version that was released after the updates subscription has expired. Unfortunately, this will require the change of the license text after each license renewal. But on the other hand, the licensing code is cleaner and the distribution of the dlls is much simpler and done in a much more common way for the .Net ecosystem.

Of course, the current way of distributing evaluation and commercial versions with windows installer will still be available and fully supported in the future.

One of the advantages of using windows installer was that with the dlls it was also possible to install the sample projects for the libraries. This is not possible with NuGet distribution.

Again, there is a more conventional way in the .Net ecosystem to distribute sample projects. It is GitHub. So, when a NuGet package is installed with the Nuget Package Manager, a readme file is displayed. And the readme file shows the user a link to GitHub repositories with sample projects.

Currently, the following two repositories are available (contain solutions for standard .NET framework and for Core 3):

https://github.com/ab4d/Ab3d.PowerToys.Wpf.Samples

https://github.com/ab4d/Ab3d.DXEngine.Wpf.Samples

I am planning to add more repositories in the future.

I am also planning to add NuGet support for Ab2d.ReaderSvg, Ab2d.ReaderWmf and Ab3d.Reader3ds libraries.

Now each version of the library comes with many different variants - commercial, NuGet, core 3, etc. How do you know which one is which? This can be read from the revision number. If it is below 1000, then it is an evaluation version that was installed with windows installer; if it is between 1000 and 2000 then it is a commercial version that was installed with windows installer; if it is above 2000 then it has universal licensing and is distributed through NuGet. Also, the framework version is encoded into the revision - the last 3 digits tell you: if they are 35, then the library is compiled with .Net 3.5; 40 means it is compiled with .Net 4.0; 45 means .Net 4.5 and 300 means .NET Core 3.

Let me finish with the following question: should a WPF project be ported to .NET Core 3?

Here I would agree with Microsoft's recommendation: if your project is already completed and require only minimal maintenance, then leave it on a standard .Net framework. If the project is still heavily under development, then it is worth considering to migrate to .NET Core 3 for one of the next releases of your project. If you are starting a new WPF project, then it is recommended to use .NET Core 3.

A new major version of the Ab3d.PowerToys library has been released!

The new version brings many new features, significantly improves performance in some cases and also fixes a few issues.

I am sure that most of you will find your own favorite feature or improvement in this version. For me, the most important addition is a new ModelScalarVisual3D class.

The ModelScalarVisual3D is a control that provides a simple way for the user to scale a selected 3D model - it is a usual control in almost all 3D modeling applications. This way the Ab3d.PowerToys library provides all three standard transformation controls: translation (with ModelMoverVisual3D), rotation (with ModelRotatorVisual3D) and scale (with ModelScalarVisual3D). There is also a new "Ducks lake" sample that demonstrates the usage of all three:

Another very nice new feature that I really like is support for rendering 3D streamlines. 3D streamlines are 3D lines that represent a flow of water or air with different colors. Streamlines are used many times to show simulation results or show sensor data. With Ab3d.PowerToys library they can be shown with an updated TubePathMesh3D class. The class is created with a collection of 3D positions that define the tube positions. With the new version, it is now possible to also specify texture coordinates for each tube path position. This way it is possible to assign a texture with a color gradient to the TubePath and use the texture coordinates to specify which color should be shown for each tube path position.

TubePath always shows a cylindrical tube along the specified path. But if you want to show some other shape along a path, then you can use an updated CreateExtrudedMeshGeometry method (in Ab3d.Meshes.Mesh3DFactory namespace). Previously it was possible to extrude a 2D shape into a 3D object only by providing a single 3D vector. Now you can provide a list of 3D positions and the new method will extrude the 2D shape along the provided positions.

Many of you have already tried to create a custom 3D mesh with defining custom positions, triangle indices and texture coordinates. The "best friend" for this task is a piece of paper and a pencil. This way you can draw the 3D object schema to a paper and then number the positions. This makes it much easier to see the position indexes that will form the object triangles. For those users, the new version of Ab3d.PowerToys is introducing a new "best friend": MeshInspectorOverlay control. It is a control that is derived from Canvas and can show position indexes, triangle indexes and orientation of positions in each triangle. You just add the MeshInspectorOverlay control to your visual tree (it should be added after the Viewport3D control and should occupy the same space), then assign MeshGeometry3D and Camera properties and after that the mesh details will be written on top of the 3D object. 

If you are interested in MeshInspectorOverlay then I would like to remind you about the Ab3d.Utilities.Dumper class. This class defines many methods that can be used at design time in Visual Studio Immediate window to show many details about objects used in 3D scene. For example, its Dump method can show many details about a MeshGeometry3D, Model3D or Matrix3D. That method is also defined as an extension method on those classes. There is also a DumpHierarchy extension method that can be used on Model3D, Visual3D or even Viewport3D. Try them.

Most of the samples under "Objects 3D" have been updated and can now show 3D model details with using the MeshInspectorOverlay. Here is a screenshot of MeshInspectorOverlay sample that also shows many of its properties:

There are also some other nice new features. But let me now describe some of the performance improvements.

If you are using Boolean operations, then you will be happy to learn that this part of the library has been significantly improved. Boolean operations require a generation of Constructive solid geometry (CSG) objects where polygons in one CSG object are split based on the polygons in another CSG object. This process can create an insane amount of objects. Optimizing the creation of objects in the latest version has significantly improved the performance. What is more, if you are doing multiple Boolean operations on a single 3D object, you can now preserve the internal CSG object between all the operations (before new CGS was created each time). This can provide an even bigger speed-up. But, please do not be too excited, Boolean operations are still very complex and slow operations.

Another significant performance improvement has been done to improve getting the 3D line that is the closest to the mouse position. If you are using only Ab3d.PowerToys and WPF to render 3D lines, then this is not very relevant because showing many 3D lines in such a scenario is much more limiting that getting the closest line. But when using Ab3d.DXEngine, it is possible to show hundreds of thousands of 3D lines and in such extreme scenarios, it is essential that the code that gets the closest 3D line is fully optimized. This was achieved with heavy inlining and reordering of the code in the critical path. What is more, the methods in the LineSelectorData class have been updated in such a way that now it is possible to call them in multiple threads (for example with using Parallel.For). This way you can achieve massive performance gains.

The code in LineSelectorData was also updated to correctly handle the cases when 3D lines cross the camera's near plane (line goes behind the camera). In this case, the closest line was not always correctly calculated. Because this requires special handling of the 3D line, there is also a new Line3DTo2D method on the camera class (besides the Point3DTo2D and Rect3DTo2D methods).

There are also some other fixes available. To get the full list of new features and changes see the Ab3d.PowerToys versions history.