Cycles: Add support for native OptiX curve primitive

This patch adds support for the curve primitive from OptiX to Cycles. It's currently hidden
behind a debug option, since there can be some slight rendering differences still (because no
backface culling is performed and something seems off with endcaps). The curve primitive
was added with the OptiX 7.1 SDK and requires a r450 driver or newer, so this also updates
the codebase to be able to build with the new SDK.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D8223

1 files changed, 6 insertions, 3 deletions

diff --git a/intern/cycles/kernel/geom/geom_curve_intersect.h b/intern/cycles/kernel/geom/geom_curve_intersect.h
index c04dbee52cc..06d2c016f5b 100644
--- a/intern/cycles/kernel/geom/geom_curve_intersect.h
+++ b/intern/cycles/kernel/geom/geom_curve_intersect.h
@@ -734,7 +734,6 @@ ccl_device_inline void curve_shader_setup(KernelGlobals *kg,
   }
 
   sd->u = isect->u;
-  sd->v = isect->v;
 
   P = P + D * t;
 
@@ -750,6 +749,7 @@ ccl_device_inline void curve_shader_setup(KernelGlobals *kg,
 
     sd->N = normalize(sine * bitangent - cosine * normalize(cross(tangent, bitangent)));
     sd->Ng = -D;
+    sd->v = isect->v;
 
 #  if 0
     /* This approximates the position and geometric normal of a thick curve too,
@@ -764,8 +764,11 @@ ccl_device_inline void curve_shader_setup(KernelGlobals *kg,
      * This could be optimized by recording the normal in the intersection,
      * however for Optix this would go beyond the size of the payload. */
     const float3 P_inside = float4_to_float3(catmull_rom_basis_eval(P_curve, isect->u));
-    sd->Ng = normalize(P - P_inside);
-    sd->N = sd->Ng;
+    const float3 Ng = normalize(P - P_inside);
+
+    sd->N = Ng;
+    sd->Ng = Ng;
+    sd->v = 0.0f;
   }
 
 #  ifdef __DPDU__