Commit: d6e769d32e7939e3bbd1986cdc4abd2b13135eab Author: Lukas Stockner Date: Thu Jul 26 16:48:15 2018 +0200 Branches: master https://developer.blender.org/rBd6e769d32e7939e3bbd1986cdc4abd2b13135eab
Cycles: Add reflection fix to Bump and Normal Map nodes While changing the shading normal is a great way to add additional detail to a model, there are some problems with it. One of them is that at grazing angles and/or strong changes to the normal, the reflected ray can end up pointing into the actual geometry, which results in a black spot. This patch helps avoid this by automatically reducing the strength of the bump/normal map if the reflected direction would end up too shallow or inside the geometry. Differential Revision: https://developer.blender.org/D2574 =================================================================== M intern/cycles/kernel/kernel_montecarlo.h M intern/cycles/kernel/shaders/node_bump.osl M intern/cycles/kernel/shaders/node_normal_map.osl M intern/cycles/kernel/shaders/stdosl.h M intern/cycles/kernel/svm/svm_displace.h M intern/cycles/kernel/svm/svm_tex_coord.h =================================================================== diff --git a/intern/cycles/kernel/kernel_montecarlo.h b/intern/cycles/kernel/kernel_montecarlo.h index 49dc1f08cc1..09a3fe8f23d 100644 --- a/intern/cycles/kernel/kernel_montecarlo.h +++ b/intern/cycles/kernel/kernel_montecarlo.h @@ -184,6 +184,35 @@ ccl_device float2 regular_polygon_sample(float corners, float rotation, float u, return make_float2(cr*p.x - sr*p.y, sr*p.x + cr*p.y); } +ccl_device float3 ensure_valid_reflection(float3 Ng, float3 I, float3 N) +{ + float3 R = 2*dot(N, I)*N - I; + if(dot(Ng, R) >= 0.05f) { + return N; + } + + /* Form coordinate system with Ng as the Z axis and N inside the X-Z-plane. + * The X axis is found by normalizing the component of N that's orthogonal to Ng. + * The Y axis isn't actually needed. + */ + float3 X = normalize(N - dot(N, Ng)*Ng); + + /* Calculate N.z and N.x in the local coordinate system. */ + float Iz = dot(I, Ng); + float Ix2 = sqr(dot(I, X)), Iz2 = sqr(Iz); + float Ix2Iz2 = Ix2 + Iz2; + + float a = sqrtf(Ix2*(Ix2Iz2 - sqr(0.05f))); + float b = Iz*0.05f + Ix2Iz2; + float c = (a + b > 0.0f)? (a + b) : (-a + b); + + float Nz = sqrtf(0.5f * c * (1.0f / Ix2Iz2)); + float Nx = sqrtf(1.0f - sqr(Nz)); + + /* Transform back into global coordinates. */ + return Nx*X + Nz*Ng; +} + CCL_NAMESPACE_END #endif /* __KERNEL_MONTECARLO_CL__ */ diff --git a/intern/cycles/kernel/shaders/node_bump.osl b/intern/cycles/kernel/shaders/node_bump.osl index 7f01cf2ca91..a2a4468d5f3 100644 --- a/intern/cycles/kernel/shaders/node_bump.osl +++ b/intern/cycles/kernel/shaders/node_bump.osl @@ -64,5 +64,7 @@ surface node_bump( if (use_object_space) { NormalOut = normalize(transform("object", "world", NormalOut)); } + + NormalOut = ensure_valid_reflection(Ng, I, NormalOut); } diff --git a/intern/cycles/kernel/shaders/node_normal_map.osl b/intern/cycles/kernel/shaders/node_normal_map.osl index 41bcac4fb10..fda6f12a5da 100644 --- a/intern/cycles/kernel/shaders/node_normal_map.osl +++ b/intern/cycles/kernel/shaders/node_normal_map.osl @@ -88,5 +88,7 @@ shader node_normal_map( if (Strength != 1.0) Normal = normalize(NormalIn + (Normal - NormalIn) * max(Strength, 0.0)); + + Normal = ensure_valid_reflection(Ng, I, Normal); } diff --git a/intern/cycles/kernel/shaders/stdosl.h b/intern/cycles/kernel/shaders/stdosl.h index df9c2010872..4a8378796ba 100644 --- a/intern/cycles/kernel/shaders/stdosl.h +++ b/intern/cycles/kernel/shaders/stdosl.h @@ -282,6 +282,36 @@ point rotate (point p, float angle, point a, point b) return transform (M, p-a) + a; } +normal ensure_valid_reflection(normal Ng, vector I, normal N) +{ + float sqr(float x) { return x*x; } + + vector R = 2*dot(N, I)*N - I; + if (dot(Ng, R) >= 0.05) { + return N; + } + + /* Form coordinate system with Ng as the Z axis and N inside the X-Z-plane. + * The X axis is found by normalizing the component of N that's orthogonal to Ng. + * The Y axis isn't actually needed. + */ + vector X = normalize(N - dot(N, Ng)*Ng); + + /* Calculate N.z and N.x in the local coordinate system. */ + float Ix = dot(I, X), Iz = dot(I, Ng); + float Ix2 = sqr(dot(I, X)), Iz2 = sqr(dot(I, Ng)); + float Ix2Iz2 = Ix2 + Iz2; + + float a = sqrt(Ix2*(Ix2Iz2 - sqr(0.05))); + float b = Iz*0.05 + Ix2Iz2; + float c = (a + b > 0.0)? (a + b) : (-a + b); + + float Nz = sqrt(0.5 * c * (1.0 / Ix2Iz2)); + float Nx = sqrt(1.0 - sqr(Nz)); + + /* Transform back into global coordinates. */ + return Nx*X + Nz*Ng; +} // Color functions diff --git a/intern/cycles/kernel/svm/svm_displace.h b/intern/cycles/kernel/svm/svm_displace.h index b85eb9c0458..0f5b3abef87 100644 --- a/intern/cycles/kernel/svm/svm_displace.h +++ b/intern/cycles/kernel/svm/svm_displace.h @@ -75,6 +75,8 @@ ccl_device void svm_node_set_bump(KernelGlobals *kg, ShaderData *sd, float *stac object_normal_transform(kg, sd, &normal_out); } + normal_out = ensure_valid_reflection(sd->Ng, sd->I, normal_out); + stack_store_float3(stack, node.w, normal_out); #endif } diff --git a/intern/cycles/kernel/svm/svm_tex_coord.h b/intern/cycles/kernel/svm/svm_tex_coord.h index 7c207083929..45c38d64763 100644 --- a/intern/cycles/kernel/svm/svm_tex_coord.h +++ b/intern/cycles/kernel/svm/svm_tex_coord.h @@ -345,6 +345,8 @@ ccl_device void svm_node_normal_map(KernelGlobals *kg, ShaderData *sd, float *st N = safe_normalize(sd->N + (N - sd->N)*strength); } + N = ensure_valid_reflection(sd->Ng, sd->I, N); + if(is_zero(N)) { N = sd->N; } _______________________________________________ Bf-blender-cvs mailing list Bf-blender-cvs@blender.org https://lists.blender.org/mailman/listinfo/bf-blender-cvs
