This project renders object (entity) information (ModelComponent ID, Mesh & Material Indices) onto a render target, which is then read by a Material shader to display.
This code is adapted from Xenko's PickingSceneRenderer class, except made to output the entire view and to make it accessible to custom shaders on materials.
Example of output of RenderTarget identifying the different ModelComponents of each entity in red, the different mesh indices (of a single model) in green (color is normalized to appear on screen):
Project Notes:
Ensure the .sdsl and .sdfx files have the Custom Tool property set to XenkoShaderKeyGenerator in Visual Studio, so it can automatically build the .cs files. This requires the Xenko plugin for Visual Studio installed.
Usage Notes:
To use in your own project, you will also need to set up the GraphicsCompositor. Refer to the images below for examples.
-
Add an
ObjectInforender stage (both effect slot name and name should be the same). -
In the
MeshRenderFeature, add the (sub) render featureObjectInfoRenderFeature, and the render stage selectorObjectInfoRenderStageSelector. -
For
ObjectInfoRenderStageSelector, set the Effect Name asObjectInfoOutputEffect(this is the name of the effect inEffects\ObjectInfoOutputEffect.sdfx), set the Object Info Render Stage to the aboveObjectInfo, Render Group can be set to whatever objects you want to be written to the texture. -
If running with the default setup, select the
Entry pointsnode, addObjectInfoSceneRendereras a child in the property (Game renderer -> Camera Renderer -> Child -> SceneRendererCollection -> Children).Important Note: Make this appear before the
Shared: Forward rendererrenderer (easiest way is to add to the end, save, then modifier theAssets\GraphicsCompositor.xkgfxcompfile directly to shift it.)
Scene Notes:
The example scene has the "Wall" entity in Render group Group10, and the ObjectInforRenderStageSelector to exclude this group, to ensure it is not captured in the render target texture, and only used for output rendering purposes only.
ObjectInfoSceneRenderer does the actual encoding (rendering) of the object info. Since it is expected to be used by the standard rendering system (eg. used in a custom shader on a material), you must make sure this renderer is ordered before the Forward renderer.
At the end of the draw call, it will set up the generated texture for consumption (consumption example is the shader ObjectInfoOutputTestShader.sdsl).
The ObjectInfoRenderFeature generates the "buffer" data, ie. the entity data we want the ObjectInfoOutputEffect to read and output, and ObjectInfoRenderStageSelector declares the effect/shader that reads this buffer data (ObjectInfoOutputEffect.sdfx & ObjectInfoOutputShader.sdsl, where the Effect Name is declared in the Graphics Compositor).
Note that in order for skinned (animated) models to be rendered correctly on the texture, we need to inherit the shaders that compute the skinned transformations. Unfortunately, we cannot add the mixin XenkoForwardShadingEffect, due to heavy ties with ShaderBase. The problem with ShaderBase is that it declares the pixel output (SV_Target0) as float4, which works fine for a float4 format texture, but our object info texture is uint2 format, so we want a pixel output of uint2.
To solve this, we essentially copy XenkoForwardShadingEffect.sdfx and most of the mixin shaders that it uses, and change every shader that inherits ShaderBase to inherit our OioShaderBase instead, which declares SV_Target0 as uint2. All these shaders are placed in Effects\ObjectInfoXenkoBaseShaders folder.
ObjectInfo render stage:
ObjectInfoSceneRenderer:
ObjectInfoRenderFeature and ObjectInfoRenderStageSelector:
