Attempts at raycast

assets/shaders/equirect_to_cube.comp

@@ -8,6 +8,45 @@ layout(set = 0, binding = 2, rgba16f) uniform writeonly restrict imageCube _Cube
 const float INV_PI = 0.31830987;
 const float HALF_INV_PI = 0.15915494;
 
+const mat3x3 MATRIX_2D_TO_CUBE[6] = mat3x3[](
+    // Positive X
+    mat3x3(
+        0,  0, -1,
+        0, -1,  0,
+        1,  0,  0
+    ),
+    // Negative X
+    mat3x3(
+         0,  0, 1,
+         0, -1, 0,
+        -1,  0, 0
+    ),
+    // Positive Y
+    mat3x3(
+        1, 0, 0,
+        0, 0, 1,
+        0, 1, 0
+    ),
+    // Negative Y
+    mat3x3(
+        1,  0,  0,
+        0,  0, -1,
+        0, -1,  0
+    ),
+    // Positive Z
+    mat3x3(
+        1,  0, 0,
+        0, -1, 0,
+        0, 0,  1
+    ),
+    // Negative Z
+    mat3x3(
+        -1,  0,  0,
+         0, -1,  0,
+         0,  0, -1
+    )
+);
+
 layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;
 void main() {
     vec2 size = vec2(imageSize(_CubemapImage).xy);
@@ -16,27 +55,7 @@ void main() {
 
     texCoord = texCoord * vec2(2.0) - vec2(1.0); // Map to range [-1, 1]
 
-    vec3 cubeCoord;
-    if (layerIndex == 0) {
-        // Positive X
-        cubeCoord = vec3(1, -texCoord.y, -texCoord.x);
-    } else if (layerIndex == 1) {
-        // Negative X
-        cubeCoord = vec3(-1, -texCoord.y, texCoord.x);
-    } else if (layerIndex == 2) {
-        // Positive Y
-        cubeCoord = vec3(texCoord.x, 1, texCoord.y);
-    } else if (layerIndex == 3) {
-        // Negative Y
-        cubeCoord = vec3(texCoord.x, -1, -texCoord.y);
-    } else if (layerIndex == 4) {
-        // Positive Z
-        cubeCoord = vec3(texCoord.x, -texCoord.y, 1);
-    } else if (layerIndex == 5) {
-        // Negative Z
-        cubeCoord = vec3(-texCoord.x, -texCoord.y, -1);
-    }
-
+    vec3 cubeCoord = MATRIX_2D_TO_CUBE[layerIndex] * vec3(texCoord, 1.0);
     vec3 cubeDir = normalize(cubeCoord);
 
     float theta = atan(cubeDir.y, cubeDir.x);
@@ -45,5 +64,5 @@ void main() {
     vec2 equirectCoord = vec2(theta * HALF_INV_PI, phi * INV_PI) + vec2(0.5);
 
     vec4 irradiance = texture(sampler2D(_EquirectangularTexture, _EquirectangularSampler), equirectCoord);
-    imageStore(_CubemapImage, ivec3(ivec2(gl_GlobalInvocationID.xy), layerIndex), irradiance);
+    imageStore(_CubemapImage, ivec3(gl_GlobalInvocationID.xyz), irradiance);
 }