1 files changed, 30 insertions, 0 deletions
diff --git a/source/blender/draw/engines/eevee/shaders/effect_downsample_cube_frag.glsl b/source/blender/draw/engines/eevee/shaders/effect_downsample_cube_frag.glsl
new file mode 100644
index 00000000000..eb463d51146
--- /dev/null
+++ b/source/blender/draw/engines/eevee/shaders/effect_downsample_cube_frag.glsl
@@ -0,0 +1,30 @@
+/**
+ * Simple downsample shader. Takes the average of the 4 texels of lower mip.
+ **/
+
+uniform samplerCube source;
+uniform float texelSize;
+
+flat in int fFace;
+
+out vec4 FragColor;
+
+const vec3 maj_axes[6] = vec3[6](vec3(1.0,  0.0,  0.0), vec3(-1.0,  0.0, 0.0), vec3(0.0, 1.0, 0.0), vec3(0.0, -1.0,  0.0), vec3( 0.0,  0.0, 1.0), vec3( 0.0,  0.0, -1.0));
+const vec3 x_axis[6]   = vec3[6](vec3(0.0,  0.0, -1.0), vec3( 0.0,  0.0, 1.0), vec3(1.0, 0.0, 0.0), vec3(1.0,  0.0,  0.0), vec3( 1.0,  0.0, 0.0), vec3(-1.0,  0.0,  0.0));
+const vec3 y_axis[6]   = vec3[6](vec3(0.0, -1.0,  0.0), vec3( 0.0, -1.0, 0.0), vec3(0.0, 0.0, 1.0), vec3(0.0,  0.0, -1.0), vec3( 0.0, -1.0, 0.0), vec3( 0.0, -1.0,  0.0));
+
+float brightness(vec3 c)
+{
+	return max(max(c.r, c.g), c.b);
+}
+
+void main()
+{
+	vec2 uvs = gl_FragCoord.xy * texelSize;
+
+	uvs = 2.0 * uvs - 1.0;
+
+	vec3 cubevec = x_axis[fFace] * uvs.x + y_axis[fFace] * uvs.y + maj_axes[fFace];
+
+	FragColor = textureLod(source, cubevec, 0.0);
+}
+\ No newline at end of file