A Slang vertex and fragment shader draw a triangle into an image with dynamic rendering (no render pass object: the pipeline names its colour format), image barriers move it to the attachment and transfer layouts, and vkCmdCopyImageToBuffer reads it back into a PPM. It is the path the Vulkan renderer's passes and screenshots take. The corner comes from SV_VulkanVertexID: Slang compiles SV_VertexID to gl_VertexIndex - gl_BaseVertex, which declares the draw-parameters capability. Validation-clean and VKTRIANGLE OK on the RTX 3070 Ti (Windows) and the M4 Pro (MoltenVK), 13824 pixels covered on both. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
30 lines
1.2 KiB
Text
30 lines
1.2 KiB
Text
// vk_triangle.slang — the first thing Ludic draws through Vulkan's graphics pipeline: three
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// corners with no vertex buffer and a colour each, the rasteriser blending between them.
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// The corner comes from SV_VulkanVertexID (gl_VertexIndex as it is): Slang compiles SV_VertexID
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// to gl_VertexIndex - gl_BaseVertex, which needs the draw-parameters capability.
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// slangc vk_triangle.slang -target spirv -profile spirv_1_5 -entry vsMain -stage vertex -o vk_triangle_vs.spv
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// slangc vk_triangle.slang -target spirv -profile spirv_1_5 -entry fsMain -stage fragment -o vk_triangle_fs.spv
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struct VOut
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{
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float4 pos : SV_Position;
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float3 col : COLOR;
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};
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[shader("vertex")]
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VOut vsMain(uint id : SV_VulkanVertexID)
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{
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// Vulkan's clip space has y pointing down, so the apex is at -y
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static const float2 corners[3] = { float2(0.0, -0.6), float2(0.6, 0.6), float2(-0.6, 0.6) };
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static const float3 colours[3] = { float3(1.0, 0.25, 0.1), float3(0.1, 1.0, 0.3), float3(0.2, 0.35, 1.0) };
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VOut o;
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o.pos = float4(corners[id], 0.0, 1.0);
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o.col = colours[id];
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return o;
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}
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[shader("fragment")]
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float4 fsMain(VOut i) : SV_Target
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{
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return float4(i.col, 1.0);
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}
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