diff options
| -rw-r--r-- | intern/cycles/kernel/geom/geom_curve_intersect.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/intern/cycles/kernel/geom/geom_curve_intersect.h b/intern/cycles/kernel/geom/geom_curve_intersect.h index b2101034bb6..a068e93790a 100644 --- a/intern/cycles/kernel/geom/geom_curve_intersect.h +++ b/intern/cycles/kernel/geom/geom_curve_intersect.h @@ -764,8 +764,10 @@ ccl_device_inline void curve_shader_setup(const KernelGlobals *kg, /* Thick curves, compute normal using direction from inside the curve. * This could be optimized by recording the normal in the intersection, * however for Optix this would go beyond the size of the payload. */ + /* NOTE: It is possible that P will be the same as P_inside (precision issues, or very small + * radius). In this case use the view direction to approximate the normal. */ const float3 P_inside = float4_to_float3(catmull_rom_basis_eval(P_curve, sd->u)); - const float3 Ng = normalize(P - P_inside); + const float3 Ng = (!isequal_float3(P, P_inside)) ? normalize(P - P_inside) : -sd->I; sd->N = Ng; sd->Ng = Ng; |