Release notes

What’s new #

Rendering #

GPU tessellator

An experimental GPU tessellation algorithm has been added to Renoir. You can enable it using the --use-fill-atlas-tessellation developer option. Fill paths are pre-processed in an atlas (on the GPU), which is later used to draw the final composited texture. The control points of cubic curves are uploaded to a vertex shader, where these are rasterized. This generally improves performance at the cost of more VRAM usage. The algorithm is used only on shapes that fit in a 1024x1024 texture. Larger shapes will be handled by the previous CPU-based solution.

Migration guide #

Migrating to 1.53

Experimental GPU tessellation algorithm #

If you rely on a custom backend and you would like to use the --use-fill-atlas-tessellation option, your custom backend has to support the following:

• Shader type ST_FillPathAtlas
• Pixel shader type PST_FillPathAtlas
• Vertex type VT_FillPathAtlas
• Renderer capability SupportsSingleChannelMSAATextures

Two new shaders have been added for the GPU tessellation: CohFillPathAtlasVS.hlsl and CohNullPS.hlsl. Cubic curves are rasterized in the vertex shader CohFillPathAtlasVS.hlsl (refer to the comment in the file for implementation details). Since the results are stored in a stencil buffer, The pixel shader CohNullPS.hlsl is a placeholder and has no effect on the final result. PST_FillPathAtlas needs to be handled by ST_StandardTexture (see the if (shaderType == 30) branch in CohShadeGeometry.ihlsl). The vertex type VT_FillPathAtlas must have the following layout (The structure is already defined in PipelineState.h):

struct FillPathAtlasVertex
{
	float4 Points01;
	float4 Points23;
	float2 FanPoint;
	float2 ResolveLevelAndIndex;
	unsigned CBData;
};

The renderer capability SupportsSingleChannelMSAATextures indicates whether the backend supports MSAA on single channel textures. If set to false, RGBA8 textures will be allocated instead of R8.

Changelog #

Version 1.53.0 #