Eevee: Add Glossy Reflection clamping

This enables reducing the noise comming from very bright light sources
(like a sun) that can be found in distant HDRIs.

The lost energy may be replaced manually by a sunlight that compensate the
this loss.

This clamping only concerns Reflection Cubmaps and is done on all on all
of them.

Setting to 0.0 disables it (default).

1 files changed, 13 insertions, 1 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/lightprobe_filter_glossy_frag.glsl b/source/blender/draw/engines/eevee/shaders/lightprobe_filter_glossy_frag.glsl
index bb23051b7e5..fdfee54f368 100644
--- a/source/blender/draw/engines/eevee/shaders/lightprobe_filter_glossy_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lightprobe_filter_glossy_frag.glsl
@@ -6,11 +6,17 @@ uniform float lodFactor;
 uniform float lodMax;
 uniform float paddingSize;
 uniform float intensityFac;
+uniform float fireflyFactor;
 
 in vec3 worldPosition;
 
 out vec4 FragColor;
 
+float brightness(vec3 c)
+{
+	return max(max(c.r, c.g), c.b);
+}
+
 vec3 octahedral_to_cubemap_proj(vec2 co)
 {
 	co = co * 2.0 - 1.0;
@@ -77,7 +83,13 @@ void main() {
 			/* 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;
+			vec3 l_col = textureLod(probeHdr, L, lod).rgb;
+
+			/* Clamped brightness. */
+			float luma = max(1e-8, brightness(l_col));
+			l_col *= 1.0 - max(0.0, luma - fireflyFactor) / luma;
+
+			out_radiance += l_col * NL;
 			weight += NL;
 		}
 	}