Cycles: remove support for rendering hair as triangle and lines

Triangles were very memory intensive. The only reason they were not removed yet
is that they gave more accurate results, but there will be an accurate 3D curve
primitive added for this.

Line rendering was always poor quality since the ends do not match up. To keep CPU
and GPU compatibility we just remove them entirely. They could be brought back if
an Embree compatible implementation is added, but it's not clear to me that there
is a use case for these that we'd consider important.

Ref T73778

Reviewers: #cycles

Subscribers:

2 files changed, 20 insertions, 60 deletions

diff --git a/intern/cycles/bvh/bvh_embree.cpp b/intern/cycles/bvh/bvh_embree.cpp
index ebefc54be88..4e064f54742 100644
--- a/intern/cycles/bvh/bvh_embree.cpp
+++ b/intern/cycles/bvh/bvh_embree.cpp
@@ -78,8 +78,7 @@ static void rtc_filter_func(const RTCFilterFunctionNArguments *args)
   KernelGlobals *kg = ctx->kg;
 
   /* Check if there is backfacing hair to ignore. */
-  if (IS_HAIR(hit->geomID) && (kernel_data.curve.curveflags & CURVE_KN_INTERPOLATE) &&
-      !(kernel_data.curve.curveflags & CURVE_KN_BACKFACING) &&
+  if (IS_HAIR(hit->geomID) && !(kernel_data.curve.curveflags & CURVE_KN_BACKFACING) &&
       !(kernel_data.curve.curveflags & CURVE_KN_RIBBONS)) {
     if (dot(make_float3(ray->dir_x, ray->dir_y, ray->dir_z),
             make_float3(hit->Ng_x, hit->Ng_y, hit->Ng_z)) > 0.0f) {
@@ -99,8 +98,7 @@ static void rtc_filter_occluded_func(const RTCFilterFunctionNArguments *args)
   KernelGlobals *kg = ctx->kg;
 
   /* For all ray types: Check if there is backfacing hair to ignore */
-  if (IS_HAIR(hit->geomID) && (kernel_data.curve.curveflags & CURVE_KN_INTERPOLATE) &&
-      !(kernel_data.curve.curveflags & CURVE_KN_BACKFACING) &&
+  if (IS_HAIR(hit->geomID) && !(kernel_data.curve.curveflags & CURVE_KN_BACKFACING) &&
       !(kernel_data.curve.curveflags & CURVE_KN_RIBBONS)) {
     if (dot(make_float3(ray->dir_x, ray->dir_y, ray->dir_z),
             make_float3(hit->Ng_x, hit->Ng_y, hit->Ng_z)) > 0.0f) {
@@ -328,7 +326,6 @@ BVHEmbree::BVHEmbree(const BVHParams &params_,
       stats(NULL),
       curve_subdivisions(params.curve_subdivisions),
       build_quality(RTC_BUILD_QUALITY_REFIT),
-      use_curves(params_.curve_flags & CURVE_KN_INTERPOLATE),
       use_ribbons(params.curve_flags & CURVE_KN_RIBBONS),
       dynamic_scene(true)
 {
@@ -726,9 +723,7 @@ void BVHEmbree::update_curve_vertex_buffer(RTCGeometry geom_id, const Hair *hair
 
   /* Catmull-Rom splines need extra CVs at the beginning and end of each curve. */
   size_t num_keys_embree = num_keys;
-  if (use_curves) {
-    num_keys_embree += num_curves * 2;
-  }
+  num_keys_embree += num_curves * 2;
 
   /* Copy the CV data to Embree */
   const int t_mid = (num_motion_steps - 1) / 2;
@@ -748,45 +743,22 @@ void BVHEmbree::update_curve_vertex_buffer(RTCGeometry geom_id, const Hair *hair
 
     assert(rtc_verts);
     if (rtc_verts) {
-      if (use_curves) {
-        const size_t num_curves = hair->num_curves();
-        for (size_t j = 0; j < num_curves; ++j) {
-          Hair::Curve c = hair->get_curve(j);
-          int fk = c.first_key;
-          int k = 1;
-          for (; k < c.num_keys + 1; ++k, ++fk) {
-            rtc_verts[k] = float3_to_float4(verts[fk]);
-            rtc_verts[k].w = curve_radius[fk];
-          }
-          /* Duplicate Embree's Catmull-Rom spline CVs at the start and end of each curve. */
-          rtc_verts[0] = rtc_verts[1];
-          rtc_verts[k] = rtc_verts[k - 1];
-          rtc_verts += c.num_keys + 2;
-        }
-      }
-      else {
-        for (size_t j = 0; j < num_keys_embree; ++j) {
-          rtc_verts[j] = float3_to_float4(verts[j]);
-          rtc_verts[j].w = curve_radius[j];
+      const size_t num_curves = hair->num_curves();
+      for (size_t j = 0; j < num_curves; ++j) {
+        Hair::Curve c = hair->get_curve(j);
+        int fk = c.first_key;
+        int k = 1;
+        for (; k < c.num_keys + 1; ++k, ++fk) {
+          rtc_verts[k] = float3_to_float4(verts[fk]);
+          rtc_verts[k].w = curve_radius[fk];
         }
+        /* Duplicate Embree's Catmull-Rom spline CVs at the start and end of each curve. */
+        rtc_verts[0] = rtc_verts[1];
+        rtc_verts[k] = rtc_verts[k - 1];
+        rtc_verts += c.num_keys + 2;
       }
     }
   }
-#  if RTC_VERSION >= 30900
-  if (!use_curves) {
-    unsigned char *flags = (unsigned char *)rtcSetNewGeometryBuffer(geom_id,
-                                                                    RTC_BUFFER_TYPE_FLAGS,
-                                                                    0,
-                                                                    RTC_FORMAT_UCHAR,
-                                                                    sizeof(unsigned char),
-                                                                    num_keys_embree);
-    flags[0] = RTC_CURVE_FLAG_NEIGHBOR_RIGHT;
-    ::memset(flags + 1,
-             RTC_CURVE_FLAG_NEIGHBOR_RIGHT | RTC_CURVE_FLAG_NEIGHBOR_RIGHT,
-             num_keys_embree - 2);
-    flags[num_keys_embree - 1] = RTC_CURVE_FLAG_NEIGHBOR_LEFT;
-  }
-#  endif
 }
 
 void BVHEmbree::add_curves(const Object *ob, const Hair *hair, int i)
@@ -822,18 +794,8 @@ void BVHEmbree::add_curves(const Object *ob, const Hair *hair, int i)
   size_t prim_tri_index_size = pack.prim_index.size();
   pack.prim_tri_index.resize(prim_tri_index_size + num_segments);
 
-#  if RTC_VERSION >= 30900
-  enum RTCGeometryType type = (!use_curves) ?
-                                  (use_ribbons ? RTC_GEOMETRY_TYPE_FLAT_LINEAR_CURVE :
-                                                 RTC_GEOMETRY_TYPE_ROUND_LINEAR_CURVE) :
-                                  (use_ribbons ? RTC_GEOMETRY_TYPE_FLAT_CATMULL_ROM_CURVE :
-                                                 RTC_GEOMETRY_TYPE_ROUND_CATMULL_ROM_CURVE);
-#  else
-  enum RTCGeometryType type = (!use_curves) ?
-                                  RTC_GEOMETRY_TYPE_FLAT_LINEAR_CURVE :
-                                  (use_ribbons ? RTC_GEOMETRY_TYPE_FLAT_CATMULL_ROM_CURVE :
-                                                 RTC_GEOMETRY_TYPE_ROUND_CATMULL_ROM_CURVE);
-#  endif
+  enum RTCGeometryType type = (use_ribbons ? RTC_GEOMETRY_TYPE_FLAT_CATMULL_ROM_CURVE :
+                                             RTC_GEOMETRY_TYPE_ROUND_CATMULL_ROM_CURVE);
 
   RTCGeometry geom_id = rtcNewGeometry(rtc_shared_device, type);
   rtcSetGeometryTessellationRate(geom_id, curve_subdivisions);
@@ -844,10 +806,8 @@ void BVHEmbree::add_curves(const Object *ob, const Hair *hair, int i)
     Hair::Curve c = hair->get_curve(j);
     for (size_t k = 0; k < c.num_segments(); ++k) {
       rtc_indices[rtc_index] = c.first_key + k;
-      if (use_curves) {
-        /* Room for extra CVs at Catmull-Rom splines. */
-        rtc_indices[rtc_index] += j * 2;
-      }
+      /* Room for extra CVs at Catmull-Rom splines. */
+      rtc_indices[rtc_index] += j * 2;
       /* Cycles specific data. */
       pack.prim_object[prim_object_size + rtc_index] = i;
       pack.prim_type[prim_type_size + rtc_index] = (PRIMITIVE_PACK_SEGMENT(
diff --git a/intern/cycles/bvh/bvh_embree.h b/intern/cycles/bvh/bvh_embree.h
index eb121d060b7..b10a741fd59 100644
--- a/intern/cycles/bvh/bvh_embree.h
+++ b/intern/cycles/bvh/bvh_embree.h
@@ -81,7 +81,7 @@ class BVHEmbree : public BVH {
   vector<RTCScene> delayed_delete_scenes;
   int curve_subdivisions;
   enum RTCBuildQuality build_quality;
-  bool use_curves, use_ribbons, dynamic_scene;
+  bool use_ribbons, dynamic_scene;
 };
 
 CCL_NAMESPACE_END