1 files changed, 28 insertions, 24 deletions

diff --git a/intern/cycles/kernel/svm/svm_fractal_noise.h b/intern/cycles/kernel/svm/svm_fractal_noise.h
index 5b2e4a28fce..57fa8c690ac 100644
--- a/intern/cycles/kernel/svm/svm_fractal_noise.h
+++ b/intern/cycles/kernel/svm/svm_fractal_noise.h
@@ -17,114 +17,118 @@
 CCL_NAMESPACE_BEGIN
 
 /* The fractal_noise_[1-4] functions are all exactly the same except for the input type. */
-ccl_device_noinline float fractal_noise_1d(float p, float octaves)
+ccl_device_noinline float fractal_noise_1d(float p, float octaves, float roughness)
 {
   float fscale = 1.0f;
   float amp = 1.0f;
+  float maxamp = 0.0f;
   float sum = 0.0f;
   octaves = clamp(octaves, 0.0f, 16.0f);
   int n = float_to_int(octaves);
   for (int i = 0; i <= n; i++) {
     float t = noise_1d(fscale * p);
     sum += t * amp;
-    amp *= 0.5f;
+    maxamp += amp;
+    amp *= clamp(roughness, 0.0f, 1.0f);
     fscale *= 2.0f;
   }
   float rmd = octaves - floorf(octaves);
   if (rmd != 0.0f) {
     float t = noise_1d(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 (1.0f - rmd) * sum + rmd * sum2;
   }
   else {
-    sum *= ((float)(1 << n) / (float)((1 << (n + 1)) - 1));
-    return sum;
+    return sum / maxamp;
   }
 }
 
 /* The fractal_noise_[1-4] functions are all exactly the same except for the input type. */
-ccl_device_noinline float fractal_noise_2d(float2 p, float octaves)
+ccl_device_noinline float fractal_noise_2d(float2 p, float octaves, float roughness)
 {
   float fscale = 1.0f;
   float amp = 1.0f;
+  float maxamp = 0.0f;
   float sum = 0.0f;
   octaves = clamp(octaves, 0.0f, 16.0f);
   int n = float_to_int(octaves);
   for (int i = 0; i <= n; i++) {
     float t = noise_2d(fscale * p);
     sum += t * amp;
-    amp *= 0.5f;
+    maxamp += amp;
+    amp *= clamp(roughness, 0.0f, 1.0f);
     fscale *= 2.0f;
   }
   float rmd = octaves - floorf(octaves);
   if (rmd != 0.0f) {
     float t = noise_2d(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 (1.0f - rmd) * sum + rmd * sum2;
   }
   else {
-    sum *= ((float)(1 << n) / (float)((1 << (n + 1)) - 1));
-    return sum;
+    return sum / maxamp;
   }
 }
 
 /* The fractal_noise_[1-4] functions are all exactly the same except for the input type. */
-ccl_device_noinline float fractal_noise_3d(float3 p, float octaves)
+ccl_device_noinline float fractal_noise_3d(float3 p, float octaves, float roughness)
 {
   float fscale = 1.0f;
   float amp = 1.0f;
+  float maxamp = 0.0f;
   float sum = 0.0f;
   octaves = clamp(octaves, 0.0f, 16.0f);
   int n = float_to_int(octaves);
   for (int i = 0; i <= n; i++) {
     float t = noise_3d(fscale * p);
     sum += t * amp;
-    amp *= 0.5f;
+    maxamp += amp;
+    amp *= clamp(roughness, 0.0f, 1.0f);
     fscale *= 2.0f;
   }
   float rmd = octaves - floorf(octaves);
   if (rmd != 0.0f) {
     float t = noise_3d(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 (1.0f - rmd) * sum + rmd * sum2;
   }
   else {
-    sum *= ((float)(1 << n) / (float)((1 << (n + 1)) - 1));
-    return sum;
+    return sum / maxamp;
   }
 }
 
 /* The fractal_noise_[1-4] functions are all exactly the same except for the input type. */
-ccl_device_noinline float fractal_noise_4d(float4 p, float octaves)
+ccl_device_noinline float fractal_noise_4d(float4 p, float octaves, float roughness)
 {
   float fscale = 1.0f;
   float amp = 1.0f;
+  float maxamp = 0.0f;
   float sum = 0.0f;
   octaves = clamp(octaves, 0.0f, 16.0f);
   int n = float_to_int(octaves);
   for (int i = 0; i <= n; i++) {
     float t = noise_4d(fscale * p);
     sum += t * amp;
-    amp *= 0.5f;
+    maxamp += amp;
+    amp *= clamp(roughness, 0.0f, 1.0f);
     fscale *= 2.0f;
   }
   float rmd = octaves - floorf(octaves);
   if (rmd != 0.0f) {
     float t = noise_4d(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 (1.0f - rmd) * sum + rmd * sum2;
   }
   else {
-    sum *= ((float)(1 << n) / (float)((1 << (n + 1)) - 1));
-    return sum;
+    return sum / maxamp;
   }
 }