1 files changed, 49 insertions, 0 deletions
diff --git a/source/blender/draw/engines/eevee/shaders/probe_filter_frag.glsl b/source/blender/draw/engines/eevee/shaders/probe_filter_frag.glsl
new file mode 100644
index 00000000000..bee674e3e76
--- /dev/null
+++ b/source/blender/draw/engines/eevee/shaders/probe_filter_frag.glsl
@@ -0,0 +1,49 @@
+
+uniform samplerCube probeHdr;
+uniform float roughnessSquared;
+uniform float lodFactor;
+uniform float lodMax;
+
+in vec3 worldPosition;
+
+out vec4 FragColor;
+
+void main() {
+	vec3 N, T, B, V;
+
+	vec3 R = normalize(worldPosition);
+
+	/* Isotropic assumption */
+	N = V = R;
+
+	make_orthonormal_basis(N, T, B); /* Generate tangent space */
+
+	/* Noise to dither the samples */
+	/* Note : ghosting is better looking than noise. */
+	// setup_noise();
+
+	/* Integrating Envmap */
+	float weight = 0.0;
+	vec3 out_radiance = vec3(0.0);
+	for (float i = 0; i < sampleCount; i++) {
+		vec3 H = sample_ggx(i, roughnessSquared, N, T, B); /* Microfacet normal */
+		vec3 L = -reflect(V, H);
+		float NL = dot(N, L);
+
+		if (NL > 0.0) {
+			float NH = max(1e-8, dot(N, H)); /* cosTheta */
+
+			/* Coarse Approximation of the mapping distortion
+			 * Unit Sphere -> Cubemap Face */
+			const float dist = 4.0 * M_PI / 6.0;
+			float pdf = pdf_ggx_reflect(NH, roughnessSquared);
+			/* http://http.developer.nvidia.com/GPUGems3/gpugems3_ch20.html : Equation 13 */
+			float lod = clamp(lodFactor - 0.5 * log2(pdf * dist), 0.0, lodMax) ;
+
+			out_radiance += textureLod(probeHdr, L, lod).rgb * NL;
+			weight += NL;
+		}
+	}
+
+	FragColor = vec4(out_radiance / weight, 1.0);
+}
+\ No newline at end of file