Commit: d9cc3ea2c6e8cfd17612c35a82050cb01d8070ec
Author: Lukas Stockner
Date: Mon Jul 25 16:02:25 2016 +0200
Branches: master
https://developer.blender.org/rBd9cc3ea2c6e8cfd17612c35a82050cb01d8070ec
Cycles: Fix rays parallel to the surface in the triangle refine and MultiGGX
code
In the triangle intersection refinement code, rays that are parallel to the
triangle caused a divide by zero.
These rays might initially hit the triangle due to the watertight intersection
test, but are very rare - therefore, just skipping the refinement for them
works fine.
Also, a few remaining issues in the MultiGGX code are fixed that were caused by
rays parallel to the surface (which happened more often there due to smooth
shading).
===================================================================
M intern/cycles/kernel/closure/bsdf_microfacet_multi.h
M intern/cycles/kernel/geom/geom_triangle_intersect.h
===================================================================
diff --git a/intern/cycles/kernel/closure/bsdf_microfacet_multi.h
b/intern/cycles/kernel/closure/bsdf_microfacet_multi.h
index deb3d24..acb50ce 100644
--- a/intern/cycles/kernel/closure/bsdf_microfacet_multi.h
+++ b/intern/cycles/kernel/closure/bsdf_microfacet_multi.h
@@ -42,7 +42,7 @@ ccl_device_inline float D_ggx_aniso(const float3 wm, const
float2 alpha)
/* Sample slope distribution (based on page 14 of the supplemental
implementation). */
ccl_device_inline float2 mf_sampleP22_11(const float cosI, const float2 randU)
{
- if(cosI > 0.9999f) {
+ if(cosI > 0.9999f || cosI < 1e-6f) {
const float r = sqrtf(randU.x / (1.0f - randU.x));
const float phi = M_2PI_F * randU.y;
return make_float2(r*cosf(phi), r*sinf(phi));
@@ -117,7 +117,7 @@ ccl_device_inline float3 mf_eval_phase_glossy(const float3
w, const float lambda
if(dotW_WH < 0.0f)
return make_float3(0.0f, 0.0f, 0.0f);
- float phase = max(0.0f, dotW_WH) * 0.25f / (pArea * dotW_WH);
+ float phase = max(0.0f, dotW_WH) * 0.25f / max(pArea * dotW_WH, 1e-7f);
if(alpha.x == alpha.y)
phase *= D_ggx(wh, alpha.x);
else
@@ -200,9 +200,9 @@ ccl_device_inline float mf_lambda(const float3 w, const
float2 alpha)
if(w.z > 0.9999f)
return 0.0f;
else if(w.z < -0.9999f)
- return -1.0f;
+ return -0.9999f;
- const float inv_wz2 = 1.0f / (w.z*w.z);
+ const float inv_wz2 = 1.0f / max(w.z*w.z, 1e-7f);
const float2 wa = make_float2(w.x, w.y)*alpha;
float v = sqrtf(1.0f + dot(wa, wa) * inv_wz2);
if(w.z <= 0.0f)
@@ -271,7 +271,10 @@ ccl_device_inline float mf_ggx_albedo(float r)
ccl_device_inline float mf_ggx_pdf(const float3 wi, const float3 wo, const
float alpha)
{
- return 0.25f * D_ggx(normalize(wi+wo), alpha) / ((1.0f + mf_lambda(wi,
make_float2(alpha, alpha))) * wi.z) + (1.0f - mf_ggx_albedo(alpha)) * wo.z;
+ float D = D_ggx(normalize(wi+wo), alpha);
+ float lambda = mf_lambda(wi, make_float2(alpha, alpha));
+ float albedo = mf_ggx_albedo(alpha);
+ return 0.25f * D / max((1.0f + lambda) * wi.z, 1e-7f) + (1.0f - albedo)
* wo.z;
}
ccl_device_inline float mf_ggx_aniso_pdf(const float3 wi, const float3 wo,
const float2 alpha)
diff --git a/intern/cycles/kernel/geom/geom_triangle_intersect.h
b/intern/cycles/kernel/geom/geom_triangle_intersect.h
index caa6c9d..eb0decc 100644
--- a/intern/cycles/kernel/geom/geom_triangle_intersect.h
+++ b/intern/cycles/kernel/geom/geom_triangle_intersect.h
@@ -342,9 +342,16 @@ ccl_device_inline float3 triangle_refine(KernelGlobals *kg,
float3 tvec = make_float3(P.x - tri_c.x, P.y - tri_c.y, P.z - tri_c.z);
float3 qvec = cross(tvec, edge1);
float3 pvec = cross(D, edge2);
- float rt = dot(edge2, qvec) / dot(edge1, pvec);
-
- P = P + D*rt;
+ float det = dot(edge1, pvec);
+ if(det != 0.0f) {
+ /* If determinant is zero it means ray lies in the plane of
+ * the triangle. It is possible in theory due to watertight
+ * nature of triangle intersection. For suc hcases we simply
+ * don't refine intersection hoping it'll go all fine.
+ */
+ float rt = dot(edge2, qvec) / det;
+ P = P + D*rt;
+ }
if(isect->object != OBJECT_NONE) {
# ifdef __OBJECT_MOTION__
@@ -400,9 +407,16 @@ ccl_device_inline float3
triangle_refine_subsurface(KernelGlobals *kg,
float3 tvec = make_float3(P.x - tri_c.x, P.y - tri_c.y, P.z - tri_c.z);
float3 qvec = cross(tvec, edge1);
float3 pvec = cross(D, edge2);
- float rt = dot(edge2, qvec) / dot(edge1, pvec);
-
- P = P + D*rt;
+ float det = dot(edge1, pvec);
+ if(det != 0.0f) {
+ /* If determinant is zero it means ray lies in the plane of
+ * the triangle. It is possible in theory due to watertight
+ * nature of triangle intersection. For such cases we simply
+ * don't refine intersection hoping it'll go all fine.
+ */
+ float rt = dot(edge2, qvec) / det;
+ P = P + D*rt;
+ }
#endif /* __INTERSECTION_REFINE__ */
if(isect->object != OBJECT_NONE) {
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