Cycles bump node: change the Strength value to work better, previously it would

give results that were either too weak or too strong, this makes it give more
predictable results. The downside is that it breaks backwards compatibility but
the previous behavior was almost broken.

intern/cycles/kernel/shaders/node_bump.osl

@@ -40,10 +40,12 @@ surface node_bump(
 	float det = dot(dPdx, Rx);
 	vector surfgrad = (SampleX - SampleCenter) * Rx + (SampleY - SampleCenter) * Ry;
 
-	surfgrad *= Strength;
 	float absdet = fabs(det);
+
+	float strength = clamp(Strength, 0.0, 1.0);
 	
 	/* compute and output perturbed normal */
 	NormalOut = normalize(absdet * NormalIn - sign(det) * surfgrad);
+	NormalOut = normalize(strength*NormalOut + (1.0 - strength)*NormalIn);
 }