1 files changed, 28 insertions, 24 deletions

diff --git a/source/blender/gpu/shaders/material/gpu_shader_material_fractal_noise.glsl b/source/blender/gpu/shaders/material/gpu_shader_material_fractal_noise.glsl
index 701b07b4aae..f25691c1a83 100644
--- a/source/blender/gpu/shaders/material/gpu_shader_material_fractal_noise.glsl
+++ b/source/blender/gpu/shaders/material/gpu_shader_material_fractal_noise.glsl
@@ -1,111 +1,115 @@
 /* The fractal_noise functions are all exactly the same except for the input type. */
-float fractal_noise(float p, float octaves)
+float fractal_noise(float p, float octaves, float roughness)
 {
   float fscale = 1.0;
   float amp = 1.0;
+  float maxamp = 0.0;
   float sum = 0.0;
   octaves = clamp(octaves, 0.0, 16.0);
   int n = int(octaves);
   for (int i = 0; i <= n; i++) {
     float t = noise(fscale * p);
     sum += t * amp;
-    amp *= 0.5;
+    maxamp += amp;
+    amp *= clamp(roughness, 0.0, 1.0);
     fscale *= 2.0;
   }
   float rmd = octaves - floor(octaves);
   if (rmd != 0.0) {
     float t = noise(fscale * p);
     float sum2 = sum + t * amp;
-    sum *= (float(1 << n) / float((1 << (n + 1)) - 1));
-    sum2 *= (float(1 << (n + 1)) / float((1 << (n + 2)) - 1));
+    sum /= maxamp;
+    sum2 /= maxamp + amp;
     return (1.0 - rmd) * sum + rmd * sum2;
   }
   else {
-    sum *= (float(1 << n) / float((1 << (n + 1)) - 1));
-    return sum;
+    return sum / maxamp;
   }
 }
 
 /* The fractal_noise functions are all exactly the same except for the input type. */
-float fractal_noise(vec2 p, float octaves)
+float fractal_noise(vec2 p, float octaves, float roughness)
 {
   float fscale = 1.0;
   float amp = 1.0;
+  float maxamp = 0.0;
   float sum = 0.0;
   octaves = clamp(octaves, 0.0, 16.0);
   int n = int(octaves);
   for (int i = 0; i <= n; i++) {
     float t = noise(fscale * p);
     sum += t * amp;
-    amp *= 0.5;
+    maxamp += amp;
+    amp *= clamp(roughness, 0.0, 1.0);
     fscale *= 2.0;
   }
   float rmd = octaves - floor(octaves);
   if (rmd != 0.0) {
     float t = noise(fscale * p);
     float sum2 = sum + t * amp;
-    sum *= (float(1 << n) / float((1 << (n + 1)) - 1));
-    sum2 *= (float(1 << (n + 1)) / float((1 << (n + 2)) - 1));
+    sum /= maxamp;
+    sum2 /= maxamp + amp;
     return (1.0 - rmd) * sum + rmd * sum2;
   }
   else {
-    sum *= (float(1 << n) / float((1 << (n + 1)) - 1));
-    return sum;
+    return sum / maxamp;
   }
 }
 
 /* The fractal_noise functions are all exactly the same except for the input type. */
-float fractal_noise(vec3 p, float octaves)
+float fractal_noise(vec3 p, float octaves, float roughness)
 {
   float fscale = 1.0;
   float amp = 1.0;
+  float maxamp = 0.0;
   float sum = 0.0;
   octaves = clamp(octaves, 0.0, 16.0);
   int n = int(octaves);
   for (int i = 0; i <= n; i++) {
     float t = noise(fscale * p);
     sum += t * amp;
-    amp *= 0.5;
+    maxamp += amp;
+    amp *= clamp(roughness, 0.0, 1.0);
     fscale *= 2.0;
   }
   float rmd = octaves - floor(octaves);
   if (rmd != 0.0) {
     float t = noise(fscale * p);
     float sum2 = sum + t * amp;
-    sum *= (float(1 << n) / float((1 << (n + 1)) - 1));
-    sum2 *= (float(1 << (n + 1)) / float((1 << (n + 2)) - 1));
+    sum /= maxamp;
+    sum2 /= maxamp + amp;
     return (1.0 - rmd) * sum + rmd * sum2;
   }
   else {
-    sum *= (float(1 << n) / float((1 << (n + 1)) - 1));
-    return sum;
+    return sum / maxamp;
   }
 }
 
 /* The fractal_noise functions are all exactly the same except for the input type. */
-float fractal_noise(vec4 p, float octaves)
+float fractal_noise(vec4 p, float octaves, float roughness)
 {
   float fscale = 1.0;
   float amp = 1.0;
+  float maxamp = 0.0;
   float sum = 0.0;
   octaves = clamp(octaves, 0.0, 16.0);
   int n = int(octaves);
   for (int i = 0; i <= n; i++) {
     float t = noise(fscale * p);
     sum += t * amp;
-    amp *= 0.5;
+    maxamp += amp;
+    amp *= clamp(roughness, 0.0, 1.0);
     fscale *= 2.0;
   }
   float rmd = octaves - floor(octaves);
   if (rmd != 0.0) {
     float t = noise(fscale * p);
     float sum2 = sum + t * amp;
-    sum *= (float(1 << n) / float((1 << (n + 1)) - 1));
-    sum2 *= (float(1 << (n + 1)) / float((1 << (n + 2)) - 1));
+    sum /= maxamp;
+    sum2 /= maxamp + amp;
     return (1.0 - rmd) * sum + rmd * sum2;
   }
   else {
-    sum *= (float(1 << n) / float((1 << (n + 1)) - 1));
-    return sum;
+    return sum / maxamp;
   }
 }