1 files changed, 15 insertions, 0 deletions
diff --git a/intern/cycles/util/util_math.h b/intern/cycles/util/util_math.h
index 17bb766445d..53e528de66e 100644
--- a/intern/cycles/util/util_math.h
+++ b/intern/cycles/util/util_math.h
@@ -294,6 +294,21 @@ ccl_device_inline float mix(float a, float b, float t)
 {
   return a + t * (b - a);
 }
+
+ccl_device_inline float smoothstep(float edge0, float edge1, float x)
+{
+  float result;
+  if (x < edge0)
+    result = 0.0f;
+  else if (x >= edge1)
+    result = 1.0f;
+  else {
+    float t = (x - edge0) / (edge1 - edge0);
+    result = (3.0f - 2.0f * t) * (t * t);
+  }
+  return result;
+}
+
 #endif /* __KERNEL_OPENCL__ */
 
 #ifndef __KERNEL_CUDA__