Hello! I am trying to write a compute shader which rasterizes a single 2D triangle. Here is the code for the shader:
cbuffer rasterizer_params : register(b0)
{
float3 default_color, tri_color;
int num_tris;
uint output_width, output_height;
float3 padding;
}
StructuredBuffer<int2> input_vertices : register(b0);
RWTexture2D<float4> output_texture : register(u0);
float3 barycentric(int2 pos, int2 a, int2 b, int2 c)
{
float3 res;
float2 v0 = pos - a;
float2 v1 = b - a;
float2 v2 = c - a;
float d20 = dot(v2, v0);
float d12 = dot(v1, v2);
float d22 = dot(v2, v2);
float d10 = dot(v1, v0);
float d11 = dot(v1, v1);
float d21 = dot(v2, v1);
float denom = d22*d11 - d21*d12;
res.y = (d10*d22 - d20*d21) / denom;
res.z = (d20*d11 - d10*d12) / denom;
res.x = 1.0f - (res.y + res.z);
return res;
}
float3 rasterize(int2 pos, int2 vert0, int2 vert1, int2 vert2)
{
float3 res = barycentric(pos, vert0, vert1, vert2);
if(res.x >= 0.0f && res.y >= 0.0f && res.z >= 0.0f)
return tri_color;
else
return default_color;
}
[numthreads(32, 32, 1)]
void CSMain(uint2 dispatch_tid : SV_DispatchThreadID)
{
float3 pix_color;
pix_color = rasterize(
int2(dispatch_tid.x, dispatch_tid.y),
int2(0, 0),
int2(25, 0),
int2(0, 25));
output_texture[dispatch_tid.xy] = float4(pix_color.x, pix_color.y, pix_color.z, 1.0f);
}
The output is a completely black texture (meaning that none of the pixels are passing the rasterization test). I've tried running through my code in the graphics debugger. However, I've noticed that I can't read the values of a lot of variables in the code (or the appear as NaN). I assume that this is due to the way that the shader is compiled but it makes the debugger almost useless if I can't examine the values of certain variables over the execution of my program. What gives?
