1 files changed, 33 insertions, 0 deletions
diff --git a/assets/shaders/EquirectToCubemap.slang b/assets/shaders/EquirectToCubemap.slang
new file mode 100644
index 0000000..9b2ea4b
--- /dev/null
+++ b/assets/shaders/EquirectToCubemap.slang
@@ -0,0 +1,33 @@
+uniform float4x4 u_Projection;
+uniform float4x4 u_View;
+
+struct VSInput  { float3 position : POSITION; };
+struct VSOutput { float4 position : SV_Position; float3 worldPos : TEXCOORD0; };
+
+[shader("vertex")]
+VSOutput vertexMain(VSInput input)
+{
+    VSOutput output;
+    output.worldPos = input.position;
+    output.position = mul(u_Projection, mul(u_View, float4(input.position, 1.0)));
+    return output;
+}
+
+Sampler2D u_EquirectangularMap;
+static const float2 invAtan = float2(0.1591, 0.3183);
+
+float2 SampleSphericalMap(float3 v)
+{
+    float2 uv = float2(atan2(v.z, v.x), asin(v.y));
+    uv *= invAtan;
+    uv += 0.5;
+    return uv;
+}
+
+[shader("fragment")]
+float4 fragmentMain(VSOutput input) : SV_Target
+{
+    float2 uv    = SampleSphericalMap(normalize(input.worldPos));
+    float3 color = u_EquirectangularMap.Sample(uv).rgb;
+    return float4(color, 1.0);
+}