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:

5 files changed, 72 insertions, 610 deletions

diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index 1635afab210..29ef1814294 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -78,20 +78,9 @@ enum_panorama_types = (
     ('MIRRORBALL', "Mirror Ball", "Uses the mirror ball mapping"),
 )
 
-enum_curve_primitives = (
-    ('TRIANGLES', "Triangles", "Create triangle geometry around strands"),
-    ('LINE_SEGMENTS', "Line Segments", "Use line segment primitives"),
-    ('CURVE_SEGMENTS', "Curve Segments", "Use segmented cardinal curve primitives"),
-)
-
-enum_triangle_curves = (
-    ('CAMERA_TRIANGLES', "Planes", "Create individual triangles forming planes that face camera"),
-    ('TESSELLATED_TRIANGLES', "Tessellated", "Create mesh surrounding each strand"),
-)
-
 enum_curve_shape = (
-    ('RIBBONS', "Ribbons", "Ignore thickness of each strand"),
-    ('THICK', "Thick", "Use thickness of strand when rendering"),
+    ('RIBBONS', "Ribbons", "Ignore thickness of each hair"),
+    ('THICK', "Thick", "Use thickness of hair when rendering"),
 )
 
 enum_tile_order = (
@@ -1241,12 +1230,6 @@ class CyclesObjectSettings(bpy.types.PropertyGroup):
 
 class CyclesCurveRenderSettings(bpy.types.PropertyGroup):
 
-    primitive: EnumProperty(
-        name="Primitive",
-        description="Type of primitive used for hair rendering",
-        items=enum_curve_primitives,
-        default='LINE_SEGMENTS',
-    )
     shape: EnumProperty(
         name="Shape",
         description="Form of hair",
@@ -1255,7 +1238,7 @@ class CyclesCurveRenderSettings(bpy.types.PropertyGroup):
     )
     cull_backfacing: BoolProperty(
         name="Cull Back-faces",
-        description="Do not test the back-face of each strand",
+        description="Do not test the back-face of each hair",
         default=True,
     )
     use_curves: BoolProperty(
@@ -1263,12 +1246,6 @@ class CyclesCurveRenderSettings(bpy.types.PropertyGroup):
         description="Activate Cycles hair rendering for particle system",
         default=True,
     )
-    resolution: IntProperty(
-        name="Resolution",
-        description="Resolution of generated mesh",
-        min=3, max=64,
-        default=3,
-    )
     subdivisions: IntProperty(
         name="Subdivisions",
         description="Number of subdivisions used in Cardinal curve intersection (power of 2)",
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 78a44881743..b6d19b1d4a7 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -406,14 +406,11 @@ class CYCLES_RENDER_PT_hair(CyclesButtonsPanel, Panel):
 
         col = layout.column()
         col.prop(ccscene, "shape", text="Shape")
-        if not (ccscene.primitive in {'CURVE_SEGMENTS', 'LINE_SEGMENTS'} and ccscene.shape == 'RIBBONS'):
-            col.prop(ccscene, "cull_backfacing", text="Cull back-faces")
-        col.prop(ccscene, "primitive", text="Primitive")
-
-        if ccscene.primitive == 'TRIANGLES' and ccscene.shape == 'THICK':
-            col.prop(ccscene, "resolution", text="Resolution")
-        elif ccscene.primitive == 'CURVE_SEGMENTS':
+        if ccscene.shape == 'RIBBONS':
+            # TODO: use for embree
             col.prop(ccscene, "subdivisions", text="Curve subdivisions")
+        else:
+            col.prop(ccscene, "cull_backfacing", text="Cull back-faces")
 
 
 class CYCLES_RENDER_PT_volumes(CyclesButtonsPanel, Panel):
diff --git a/intern/cycles/blender/blender_curves.cpp b/intern/cycles/blender/blender_curves.cpp
index 847a43c5f34..43fe653fda4 100644
--- a/intern/cycles/blender/blender_curves.cpp
+++ b/intern/cycles/blender/blender_curves.cpp
@@ -18,7 +18,6 @@
 #include "render/camera.h"
 #include "render/curves.h"
 #include "render/hair.h"
-#include "render/mesh.h"
 #include "render/object.h"
 #include "render/scene.h"
 
@@ -39,27 +38,6 @@ ParticleCurveData::~ParticleCurveData()
 {
 }
 
-static void interp_weights(float t, float data[4])
-{
-  /* Cardinal curve interpolation */
-  float t2 = t * t;
-  float t3 = t2 * t;
-  float fc = 0.71f;
-
-  data[0] = -fc * t3 + 2.0f * fc * t2 - fc * t;
-  data[1] = (2.0f - fc) * t3 + (fc - 3.0f) * t2 + 1.0f;
-  data[2] = (fc - 2.0f) * t3 + (3.0f - 2.0f * fc) * t2 + fc * t;
-  data[3] = fc * t3 - fc * t2;
-}
-
-static void curveinterp_v3_v3v3v3v3(
-    float3 *p, float3 *v1, float3 *v2, float3 *v3, float3 *v4, const float w[4])
-{
-  p->x = v1->x * w[0] + v2->x * w[1] + v3->x * w[2] + v4->x * w[3];
-  p->y = v1->y * w[0] + v2->y * w[1] + v3->y * w[2] + v4->y * w[3];
-  p->z = v1->z * w[0] + v2->z * w[1] + v3->z * w[2] + v4->z * w[3];
-}
-
 static float shaperadius(float shape, float root, float tip, float time)
 {
   assert(time >= 0.0f);
@@ -77,43 +55,13 @@ static float shaperadius(float shape, float root, float tip, float time)
 
 /* curve functions */
 
-static void InterpolateKeySegments(
-    int seg, int segno, int key, int curve, float3 *keyloc, float *time, ParticleCurveData *CData)
-{
-  float3 ckey_loc1 = CData->curvekey_co[key];
-  float3 ckey_loc2 = ckey_loc1;
-  float3 ckey_loc3 = CData->curvekey_co[key + 1];
-  float3 ckey_loc4 = ckey_loc3;
-
-  if (key > CData->curve_firstkey[curve])
-    ckey_loc1 = CData->curvekey_co[key - 1];
-
-  if (key < CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 2)
-    ckey_loc4 = CData->curvekey_co[key + 2];
-
-  float time1 = CData->curvekey_time[key] / CData->curve_length[curve];
-  float time2 = CData->curvekey_time[key + 1] / CData->curve_length[curve];
-
-  float dfra = (time2 - time1) / (float)segno;
-
-  if (time)
-    *time = (dfra * seg) + time1;
-
-  float t[4];
-
-  interp_weights((float)seg / (float)segno, t);
-
-  if (keyloc)
-    curveinterp_v3_v3v3v3v3(keyloc, &ckey_loc1, &ckey_loc2, &ckey_loc3, &ckey_loc4, t);
-}
-
 static bool ObtainCacheParticleData(
-    Geometry *geom, BL::Mesh *b_mesh, BL::Object *b_ob, ParticleCurveData *CData, bool background)
+    Hair *hair, BL::Mesh *b_mesh, BL::Object *b_ob, ParticleCurveData *CData, bool background)
 {
   int curvenum = 0;
   int keyno = 0;
 
-  if (!(geom && b_mesh && b_ob && CData))
+  if (!(hair && b_mesh && b_ob && CData))
     return false;
 
   Transform tfm = get_transform(b_ob->matrix_world());
@@ -129,7 +77,7 @@ static bool ObtainCacheParticleData(
 
       if ((b_part.render_type() == BL::ParticleSettings::render_type_PATH) &&
           (b_part.type() == BL::ParticleSettings::type_HAIR)) {
-        int shader = clamp(b_part.material() - 1, 0, geom->used_shaders.size() - 1);
+        int shader = clamp(b_part.material() - 1, 0, hair->used_shaders.size() - 1);
         int display_step = background ? b_part.render_step() : b_part.display_step();
         int totparts = b_psys.particles.length();
         int totchild = background ? b_psys.child_particles.length() :
@@ -203,14 +151,14 @@ static bool ObtainCacheParticleData(
   return true;
 }
 
-static bool ObtainCacheParticleUV(Geometry *geom,
+static bool ObtainCacheParticleUV(Hair *hair,
                                   BL::Mesh *b_mesh,
                                   BL::Object *b_ob,
                                   ParticleCurveData *CData,
                                   bool background,
                                   int uv_num)
 {
-  if (!(geom && b_mesh && b_ob && CData))
+  if (!(hair && b_mesh && b_ob && CData))
     return false;
 
   CData->curve_uv.clear();
@@ -266,14 +214,14 @@ static bool ObtainCacheParticleUV(Geometry *geom,
   return true;
 }
 
-static bool ObtainCacheParticleVcol(Geometry *geom,
+static bool ObtainCacheParticleVcol(Hair *hair,
                                     BL::Mesh *b_mesh,
                                     BL::Object *b_ob,
                                     ParticleCurveData *CData,
                                     bool background,
                                     int vcol_num)
 {
-  if (!(geom && b_mesh && b_ob && CData))
+  if (!(hair && b_mesh && b_ob && CData))
     return false;
 
   CData->curve_vcol.clear();
@@ -329,272 +277,6 @@ static bool ObtainCacheParticleVcol(Geometry *geom,
   return true;
 }
 
-static void ExportCurveTrianglePlanes(Mesh *mesh,
-                                      ParticleCurveData *CData,
-                                      float3 RotCam,
-                                      bool is_ortho)
-{
-  int vertexno = mesh->verts.size();
-  int vertexindex = vertexno;
-  int numverts = 0, numtris = 0;
-
-  /* compute and reserve size of arrays */
-  for (int sys = 0; sys < CData->psys_firstcurve.size(); sys++) {
-    for (int curve = CData->psys_firstcurve[sys];
-         curve < CData->psys_firstcurve[sys] + CData->psys_curvenum[sys];
-         curve++) {
-      numverts += 2 + (CData->curve_keynum[curve] - 1) * 2;
-      numtris += (CData->curve_keynum[curve] - 1) * 2;
-    }
-  }
-
-  mesh->reserve_mesh(mesh->verts.size() + numverts, mesh->num_triangles() + numtris);
-
-  /* actually export */
-  for (int sys = 0; sys < CData->psys_firstcurve.size(); sys++) {
-    for (int curve = CData->psys_firstcurve[sys];
-         curve < CData->psys_firstcurve[sys] + CData->psys_curvenum[sys];
-         curve++) {
-      float3 xbasis;
-      float3 v1;
-      float time = 0.0f;
-      float3 ickey_loc = CData->curvekey_co[CData->curve_firstkey[curve]];
-      float radius = shaperadius(
-          CData->psys_shape[sys], CData->psys_rootradius[sys], CData->psys_tipradius[sys], 0.0f);
-      v1 = CData->curvekey_co[CData->curve_firstkey[curve] + 1] -
-           CData->curvekey_co[CData->curve_firstkey[curve]];
-      if (is_ortho)
-        xbasis = normalize(cross(RotCam, v1));
-      else
-        xbasis = normalize(cross(RotCam - ickey_loc, v1));
-      float3 ickey_loc_shfl = ickey_loc - radius * xbasis;
-      float3 ickey_loc_shfr = ickey_loc + radius * xbasis;
-      mesh->add_vertex(ickey_loc_shfl);
-      mesh->add_vertex(ickey_loc_shfr);
-      vertexindex += 2;
-
-      for (int curvekey = CData->curve_firstkey[curve] + 1;
-           curvekey < CData->curve_firstkey[curve] + CData->curve_keynum[curve];
-           curvekey++) {
-        ickey_loc = CData->curvekey_co[curvekey];
-
-        if (curvekey == CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1)
-          v1 = CData->curvekey_co[curvekey] -
-               CData->curvekey_co[max(curvekey - 1, CData->curve_firstkey[curve])];
-        else
-          v1 = CData->curvekey_co[curvekey + 1] - CData->curvekey_co[curvekey - 1];
-
-        time = CData->curvekey_time[curvekey] / CData->curve_length[curve];
-        radius = shaperadius(
-            CData->psys_shape[sys], CData->psys_rootradius[sys], CData->psys_tipradius[sys], time);
-
-        if (curvekey == CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1)
-          radius = shaperadius(CData->psys_shape[sys],
-                               CData->psys_rootradius[sys],
-                               CData->psys_tipradius[sys],
-                               0.95f);
-
-        if (CData->psys_closetip[sys] &&
-            (curvekey == CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1))
-          radius = shaperadius(CData->psys_shape[sys], CData->psys_rootradius[sys], 0.0f, 0.95f);
-
-        if (is_ortho)
-          xbasis = normalize(cross(RotCam, v1));
-        else
-          xbasis = normalize(cross(RotCam - ickey_loc, v1));
-        float3 ickey_loc_shfl = ickey_loc - radius * xbasis;
-        float3 ickey_loc_shfr = ickey_loc + radius * xbasis;
-        mesh->add_vertex(ickey_loc_shfl);
-        mesh->add_vertex(ickey_loc_shfr);
-        mesh->add_triangle(
-            vertexindex - 2, vertexindex, vertexindex - 1, CData->psys_shader[sys], true);
-        mesh->add_triangle(
-            vertexindex + 1, vertexindex - 1, vertexindex, CData->psys_shader[sys], true);
-        vertexindex += 2;
-      }
-    }
-  }
-
-  mesh->resize_mesh(mesh->verts.size(), mesh->num_triangles());
-  mesh->attributes.remove(ATTR_STD_VERTEX_NORMAL);
-  mesh->attributes.remove(ATTR_STD_FACE_NORMAL);
-  mesh->add_face_normals();
-  mesh->add_vertex_normals();
-  mesh->attributes.remove(ATTR_STD_FACE_NORMAL);
-
-  /* texture coords still needed */
-}
-
-static void ExportCurveTriangleGeometry(Mesh *mesh, ParticleCurveData *CData, int resolution)
-{
-  int vertexno = mesh->verts.size();
-  int vertexindex = vertexno;
-  int numverts = 0, numtris = 0;
-
-  /* compute and reserve size of arrays */
-  for (int sys = 0; sys < CData->psys_firstcurve.size(); sys++) {
-    for (int curve = CData->psys_firstcurve[sys];
-         curve < CData->psys_firstcurve[sys] + CData->psys_curvenum[sys];
-         curve++) {
-      numverts += (CData->curve_keynum[curve] - 1) * resolution + resolution;
-      numtris += (CData->curve_keynum[curve] - 1) * 2 * resolution;
-    }
-  }
-
-  mesh->reserve_mesh(mesh->verts.size() + numverts, mesh->num_triangles() + numtris);
-
-  /* actually export */
-  for (int sys = 0; sys < CData->psys_firstcurve.size(); sys++) {
-    for (int curve = CData->psys_firstcurve[sys];
-         curve < CData->psys_firstcurve[sys] + CData->psys_curvenum[sys];
-         curve++) {
-      float3 firstxbasis = cross(make_float3(1.0f, 0.0f, 0.0f),
-                                 CData->curvekey_co[CData->curve_firstkey[curve] + 1] -
-                                     CData->curvekey_co[CData->curve_firstkey[curve]]);
-      if (!is_zero(firstxbasis))
-        firstxbasis = normalize(firstxbasis);
-      else
-        firstxbasis = normalize(cross(make_float3(0.0f, 1.0f, 0.0f),
-                                      CData->curvekey_co[CData->curve_firstkey[curve] + 1] -
-                                          CData->curvekey_co[CData->curve_firstkey[curve]]));
-
-      for (int curvekey = CData->curve_firstkey[curve];
-           curvekey < CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1;
-           curvekey++) {
-        float3 xbasis = firstxbasis;
-        float3 v1;
-        float3 v2;
-
-        if (curvekey == CData->curve_firstkey[curve]) {
-          v1 = CData->curvekey_co[min(
-                   curvekey + 2, CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1)] -
-               CData->curvekey_co[curvekey + 1];
-          v2 = CData->curvekey_co[curvekey + 1] - CData->curvekey_co[curvekey];
-        }
-        else if (curvekey == CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1) {
-          v1 = CData->curvekey_co[curvekey] - CData->curvekey_co[curvekey - 1];
-          v2 = CData->curvekey_co[curvekey - 1] -
-               CData->curvekey_co[max(curvekey - 2, CData->curve_firstkey[curve])];
-        }
-        else {
-          v1 = CData->curvekey_co[curvekey + 1] - CData->curvekey_co[curvekey];
-          v2 = CData->curvekey_co[curvekey] - CData->curvekey_co[curvekey - 1];
-        }
-
-        xbasis = cross(v1, v2);
-
-        if (len_squared(xbasis) >= 0.05f * len_squared(v1) * len_squared(v2)) {
-          firstxbasis = normalize(xbasis);
-          break;
-        }
-      }
-
-      for (int curvekey = CData->curve_firstkey[curve];
-           curvekey < CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1;
-           curvekey++) {
-        int subv = 1;
-        float3 xbasis;
-        float3 ybasis;
-        float3 v1;
-        float3 v2;
-
-        if (curvekey == CData->curve_firstkey[curve]) {
-          subv = 0;
-          v1 = CData->curvekey_co[min(
-                   curvekey + 2, CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1)] -
-               CData->curvekey_co[curvekey + 1];
-          v2 = CData->curvekey_co[curvekey + 1] - CData->curvekey_co[curvekey];
-        }
-        else if (curvekey == CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1) {
-          v1 = CData->curvekey_co[curvekey] - CData->curvekey_co[curvekey - 1];
-          v2 = CData->curvekey_co[curvekey - 1] -
-               CData->curvekey_co[max(curvekey - 2, CData->curve_firstkey[curve])];
-        }
-        else {
-          v1 = CData->curvekey_co[curvekey + 1] - CData->curvekey_co[curvekey];
-          v2 = CData->curvekey_co[curvekey] - CData->curvekey_co[curvekey - 1];
-        }
-
-        xbasis = cross(v1, v2);
-
-        if (len_squared(xbasis) >= 0.05f * len_squared(v1) * len_squared(v2)) {
-          xbasis = normalize(xbasis);
-          firstxbasis = xbasis;
-        }
-        else
-          xbasis = firstxbasis;
-
-        ybasis = normalize(cross(xbasis, v2));
-
-        for (; subv <= 1; subv++) {
-          float3 ickey_loc = make_float3(0.0f, 0.0f, 0.0f);
-          float time = 0.0f;
-
-          InterpolateKeySegments(subv, 1, curvekey, curve, &ickey_loc, &time, CData);
-
-          float radius = shaperadius(CData->psys_shape[sys],
-                                     CData->psys_rootradius[sys],
-                                     CData->psys_tipradius[sys],
-                                     time);
-
-          if ((curvekey == CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 2) &&
-              (subv == 1))
-            radius = shaperadius(CData->psys_shape[sys],
-                                 CData->psys_rootradius[sys],
-                                 CData->psys_tipradius[sys],
-                                 0.95f);
-
-          if (CData->psys_closetip[sys] && (subv == 1) &&
-              (curvekey == CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 2))
-            radius = shaperadius(CData->psys_shape[sys], CData->psys_rootradius[sys], 0.0f, 0.95f);
-
-          float angle = M_2PI_F / (float)resolution;
-          for (int section = 0; section < resolution; section++) {
-            float3 ickey_loc_shf = ickey_loc + radius * (cosf(angle * section) * xbasis +
-                                                         sinf(angle * section) * ybasis);
-            mesh->add_vertex(ickey_loc_shf);
-          }
-
-          if (subv != 0) {
-            for (int section = 0; section < resolution - 1; section++) {
-              mesh->add_triangle(vertexindex - resolution + section,
-                                 vertexindex + section,
-                                 vertexindex - resolution + section + 1,
-                                 CData->psys_shader[sys],
-                                 true);
-              mesh->add_triangle(vertexindex + section + 1,
-                                 vertexindex - resolution + section + 1,
-                                 vertexindex + section,
-                                 CData->psys_shader[sys],
-                                 true);
-            }
-            mesh->add_triangle(vertexindex - 1,
-                               vertexindex + resolution - 1,
-                               vertexindex - resolution,
-                               CData->psys_shader[sys],
-                               true);
-            mesh->add_triangle(vertexindex,
-                               vertexindex - resolution,
-                               vertexindex + resolution - 1,
-                               CData->psys_shader[sys],
-                               true);
-          }
-          vertexindex += resolution;
-        }
-      }
-    }
-  }
-
-  mesh->resize_mesh(mesh->verts.size(), mesh->num_triangles());
-  mesh->attributes.remove(ATTR_STD_VERTEX_NORMAL);
-  mesh->attributes.remove(ATTR_STD_FACE_NORMAL);
-  mesh->add_face_normals();
-  mesh->add_vertex_normals();
-  mesh->attributes.remove(ATTR_STD_FACE_NORMAL);
-
-  /* texture coords still needed */
-}
-
 static void ExportCurveSegments(Scene *scene, Hair *hair, ParticleCurveData *CData)
 {
   int num_keys = 0;
@@ -823,78 +505,6 @@ static void ExportCurveSegmentsMotion(Hair *hair, ParticleCurveData *CData, int
   }
 }
 
-static void ExportCurveTriangleUV(ParticleCurveData *CData, int resol, float2 *uvdata)
-{
-  if (uvdata == NULL)
-    return;
-  int vertexindex = 0;
-
-  for (int sys = 0; sys < CData->psys_firstcurve.size(); sys++) {
-    for (int curve = CData->psys_firstcurve[sys];
-         curve < CData->psys_firstcurve[sys] + CData->psys_curvenum[sys];
-         curve++) {
-      for (int curvekey = CData->curve_firstkey[curve];
-           curvekey < CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1;
-           curvekey++) {
-        for (int section = 0; section < resol; section++) {
-          uvdata[vertexindex] = CData->curve_uv[curve];
-          vertexindex++;
-          uvdata[vertexindex] = CData->curve_uv[curve];
-          vertexindex++;
-          uvdata[vertexindex] = CData->curve_uv[curve];
-          vertexindex++;
-          uvdata[vertexindex] = CData->curve_uv[curve];
-          vertexindex++;
-          uvdata[vertexindex] = CData->curve_uv[curve];
-          vertexindex++;
-          uvdata[vertexindex] = CData->curve_uv[curve];
-          vertexindex++;
-        }
-      }
-    }
-  }
-}
-
-static void ExportCurveTriangleVcol(ParticleCurveData *CData, int resol, uchar4 *cdata)
-{
-  if (cdata == NULL)
-    return;
-
-  int vertexindex = 0;
-
-  for (int sys = 0; sys < CData->psys_firstcurve.size(); sys++) {
-    for (int curve = CData->psys_firstcurve[sys];
-         curve < CData->psys_firstcurve[sys] + CData->psys_curvenum[sys];
-         curve++) {
-      for (int curvekey = CData->curve_firstkey[curve];
-           curvekey < CData->curve_firstkey[curve] + CData->curve_keynum[curve] - 1;
-           curvekey++) {
-        for (int section = 0; section < resol; section++) {
-          /* Encode vertex color using the sRGB curve. */
-          cdata[vertexindex] = color_float_to_byte(
-              color_srgb_to_linear_v3(CData->curve_vcol[curve]));
-          vertexindex++;
-          cdata[vertexindex] = color_float_to_byte(
-              color_srgb_to_linear_v3(CData->curve_vcol[curve]));
-          vertexindex++;
-          cdata[vertexindex] = color_float_to_byte(
-              color_srgb_to_linear_v3(CData->curve_vcol[curve]));
-          vertexindex++;
-          cdata[vertexindex] = color_float_to_byte(
-              color_srgb_to_linear_v3(CData->curve_vcol[curve]));
-          vertexindex++;
-          cdata[vertexindex] = color_float_to_byte(
-              color_srgb_to_linear_v3(CData->curve_vcol[curve]));
-          vertexindex++;
-          cdata[vertexindex] = color_float_to_byte(
-              color_srgb_to_linear_v3(CData->curve_vcol[curve]));
-          vertexindex++;
-        }
-      }
-    }
-  }
-}
-
 /* Hair Curve Sync */
 
 void BlenderSync::sync_curve_settings(BL::Depsgraph &b_depsgraph)
@@ -906,48 +516,11 @@ void BlenderSync::sync_curve_settings(BL::Depsgraph &b_depsgraph)
 
   curve_system_manager->use_curves = get_boolean(csscene, "use_curves");
 
-  curve_system_manager->primitive = (CurvePrimitiveType)get_enum(
-      csscene, "primitive", CURVE_NUM_PRIMITIVE_TYPES, CURVE_LINE_SEGMENTS);
   curve_system_manager->curve_shape = (CurveShapeType)get_enum(
       csscene, "shape", CURVE_NUM_SHAPE_TYPES, CURVE_THICK);
-  curve_system_manager->resolution = get_int(csscene, "resolution");
   curve_system_manager->subdivisions = get_int(csscene, "subdivisions");
   curve_system_manager->use_backfacing = !get_boolean(csscene, "cull_backfacing");
 
-  /* Triangles */
-  if (curve_system_manager->primitive == CURVE_TRIANGLES) {
-    /* camera facing planes */
-    if (curve_system_manager->curve_shape == CURVE_RIBBON) {
-      curve_system_manager->triangle_method = CURVE_CAMERA_TRIANGLES;
-      curve_system_manager->resolution = 1;
-    }
-    else if (curve_system_manager->curve_shape == CURVE_THICK) {
-      curve_system_manager->triangle_method = CURVE_TESSELATED_TRIANGLES;
-    }
-  }
-  /* Line Segments */
-  else if (curve_system_manager->primitive == CURVE_LINE_SEGMENTS) {
-    if (curve_system_manager->curve_shape == CURVE_RIBBON) {
-      /* tangent shading */
-      curve_system_manager->line_method = CURVE_UNCORRECTED;
-      curve_system_manager->use_encasing = true;
-      curve_system_manager->use_backfacing = false;
-      curve_system_manager->use_tangent_normal_geometry = true;
-    }
-    else if (curve_system_manager->curve_shape == CURVE_THICK) {
-      curve_system_manager->line_method = CURVE_ACCURATE;
-      curve_system_manager->use_encasing = false;
-      curve_system_manager->use_tangent_normal_geometry = false;
-    }
-  }
-  /* Curve Segments */
-  else if (curve_system_manager->primitive == CURVE_SEGMENTS) {
-    if (curve_system_manager->curve_shape == CURVE_RIBBON) {
-      curve_system_manager->primitive = CURVE_RIBBONS;
-      curve_system_manager->use_backfacing = false;
-    }
-  }
-
   if (curve_system_manager->modified_mesh(prev_curve_system_manager)) {
     BL::Depsgraph::objects_iterator b_ob;
 
@@ -994,78 +567,38 @@ bool BlenderSync::object_has_particle_hair(BL::Object b_ob)
 
 /* Old particle hair. */
 void BlenderSync::sync_particle_hair(
-    Geometry *geom, BL::Mesh &b_mesh, BL::Object &b_ob, bool motion, int motion_step)
+    Hair *hair, BL::Mesh &b_mesh, BL::Object &b_ob, bool motion, int motion_step)
 {
-  Hair *hair = (geom->type == Geometry::HAIR) ? static_cast<Hair *>(geom) : NULL;
-  Mesh *mesh = (geom->type == Geometry::MESH) ? static_cast<Mesh *>(geom) : NULL;
-
   /* obtain general settings */
   if (b_ob.mode() == b_ob.mode_PARTICLE_EDIT || b_ob.mode() == b_ob.mode_EDIT) {
     return;
   }
 
-  const int triangle_method = scene->curve_system_manager->triangle_method;
-  const int resolution = scene->curve_system_manager->resolution;
-  int used_res = 1;
-
   /* extract particle hair data - should be combined with connecting to mesh later*/
 
   ParticleCurveData CData;
 
-  ObtainCacheParticleData(geom, &b_mesh, &b_ob, &CData, !preview);
-
-  /* add hair geometry to mesh */
-  if (mesh) {
-    if (triangle_method == CURVE_CAMERA_TRIANGLES) {
-      /* obtain camera parameters */
-      float3 RotCam;
-      Camera *camera = scene->camera;
-      Transform &ctfm = camera->matrix;
-      if (camera->type == CAMERA_ORTHOGRAPHIC) {
-        RotCam = -make_float3(ctfm.x.z, ctfm.y.z, ctfm.z.z);
-      }
-      else {
-        Transform tfm = get_transform(b_ob.matrix_world());
-        Transform itfm = transform_quick_inverse(tfm);
-        RotCam = transform_point(&itfm, make_float3(ctfm.x.w, ctfm.y.w, ctfm.z.w));
-      }
-      bool is_ortho = camera->type == CAMERA_ORTHOGRAPHIC;
-      ExportCurveTrianglePlanes(mesh, &CData, RotCam, is_ortho);
-    }
-    else {
-      ExportCurveTriangleGeometry(mesh, &CData, resolution);
-      used_res = resolution;
-    }
-  }
-  else {
-    if (motion)
-      ExportCurveSegmentsMotion(hair, &CData, motion_step);
-    else
-      ExportCurveSegments(scene, hair, &CData);
-  }
+  ObtainCacheParticleData(hair, &b_mesh, &b_ob, &CData, !preview);
+
+  /* add hair geometry */
+  if (motion)
+    ExportCurveSegmentsMotion(hair, &CData, motion_step);
+  else
+    ExportCurveSegments(scene, hair, &CData);
 
   /* generated coordinates from first key. we should ideally get this from
    * blender to handle deforming objects */
   if (!motion) {
-    if (geom->need_attribute(scene, ATTR_STD_GENERATED)) {
+    if (hair->need_attribute(scene, ATTR_STD_GENERATED)) {
       float3 loc, size;
       mesh_texture_space(b_mesh, loc, size);
 
-      if (mesh) {
-        Attribute *attr_generated = mesh->attributes.add(ATTR_STD_GENERATED);
-        float3 *generated = attr_generated->data_float3();
+      Attribute *attr_generated = hair->attributes.add(ATTR_STD_GENERATED);
+      float3 *generated = attr_generated->data_float3();
 
-        for (size_t i = 0; i < mesh->verts.size(); i++)
-          generated[i] = mesh->verts[i] * size - loc;
-      }
-      else {
-        Attribute *attr_generated = hair->attributes.add(ATTR_STD_GENERATED);
-        float3 *generated = attr_generated->data_float3();
-
-        for (size_t i = 0; i < hair->num_curves(); i++) {
-          float3 co = hair->curve_keys[hair->get_curve(i).first_key];
-          generated[i] = co * size - loc;
-        }
+      for (size_t i = 0; i < hair->num_curves(); i++) {
+        float3 co = hair->curve_keys[hair->get_curve(i).first_key];
+        generated[i] = co * size - loc;
       }
     }
   }
@@ -1076,32 +609,22 @@ void BlenderSync::sync_particle_hair(
     int vcol_num = 0;
 
     for (b_mesh.vertex_colors.begin(l); l != b_mesh.vertex_colors.end(); ++l, vcol_num++) {
-      if (!geom->need_attribute(scene, ustring(l->name().c_str())))
+      if (!hair->need_attribute(scene, ustring(l->name().c_str())))
         continue;
 
-      ObtainCacheParticleVcol(geom, &b_mesh, &b_ob, &CData, !preview, vcol_num);
-
-      if (mesh) {
-        Attribute *attr_vcol = mesh->attributes.add(
-            ustring(l->name().c_str()), TypeDesc::TypeColor, ATTR_ELEMENT_CORNER_BYTE);
+      ObtainCacheParticleVcol(hair, &b_mesh, &b_ob, &CData, !preview, vcol_num);
 
-        uchar4 *cdata = attr_vcol->data_uchar4();
+      Attribute *attr_vcol = hair->attributes.add(
+          ustring(l->name().c_str()), TypeDesc::TypeColor, ATTR_ELEMENT_CURVE);
 
-        ExportCurveTriangleVcol(&CData, used_res, cdata);
-      }
-      else {
-        Attribute *attr_vcol = hair->attributes.add(
-            ustring(l->name().c_str()), TypeDesc::TypeColor, ATTR_ELEMENT_CURVE);
+      float3 *fdata = attr_vcol->data_float3();
 
-        float3 *fdata = attr_vcol->data_float3();
+      if (fdata) {
+        size_t i = 0;
 
-        if (fdata) {
-          size_t i = 0;
-
-          /* Encode vertex color using the sRGB curve. */
-          for (size_t curve = 0; curve < CData.curve_vcol.size(); curve++) {
-            fdata[i++] = color_srgb_to_linear_v3(CData.curve_vcol[curve]);
-          }
+        /* Encode vertex color using the sRGB curve. */
+        for (size_t curve = 0; curve < CData.curve_vcol.size(); curve++) {
+          fdata[i++] = color_srgb_to_linear_v3(CData.curve_vcol[curve]);
         }
       }
     }
@@ -1118,35 +641,23 @@ void BlenderSync::sync_particle_hair(
       ustring name = ustring(l->name().c_str());
 
       /* UV map */
-      if (geom->need_attribute(scene, name) || geom->need_attribute(scene, std)) {
+      if (hair->need_attribute(scene, name) || hair->need_attribute(scene, std)) {
         Attribute *attr_uv;
 
-        ObtainCacheParticleUV(geom, &b_mesh, &b_ob, &CData, !preview, uv_num);
-
-        if (mesh) {
-          if (active_render)
-            attr_uv = mesh->attributes.add(std, name);
-          else
-            attr_uv = mesh->attributes.add(name, TypeFloat2, ATTR_ELEMENT_CORNER);
+        ObtainCacheParticleUV(hair, &b_mesh, &b_ob, &CData, !preview, uv_num);
 
-          float2 *uv = attr_uv->data_float2();
-
-          ExportCurveTriangleUV(&CData, used_res, uv);
-        }
-        else {
-          if (active_render)
-            attr_uv = hair->attributes.add(std, name);
-          else
-            attr_uv = hair->attributes.add(name, TypeFloat2, ATTR_ELEMENT_CURVE);
+        if (active_render)
+          attr_uv = hair->attributes.add(std, name);
+        else
+          attr_uv = hair->attributes.add(name, TypeFloat2, ATTR_ELEMENT_CURVE);
 
-          float2 *uv = attr_uv->data_float2();
+        float2 *uv = attr_uv->data_float2();
 
-          if (uv) {
-            size_t i = 0;
+        if (uv) {
+          size_t i = 0;
 
-            for (size_t curve = 0; curve < CData.curve_uv.size(); curve++) {
-              uv[i++] = CData.curve_uv[curve];
-            }
+          for (size_t curve = 0; curve < CData.curve_uv.size(); curve++) {
+            uv[i++] = CData.curve_uv[curve];
           }
         }
       }
@@ -1344,27 +855,18 @@ void BlenderSync::sync_hair(Hair *hair, BL::Object &b_ob, bool motion, int motio
 
 void BlenderSync::sync_hair(BL::Depsgraph b_depsgraph,
                             BL::Object b_ob,
-                            Geometry *geom,
+                            Hair *hair,
                             const vector<Shader *> &used_shaders)
 {
-  Hair *hair = (geom->type == Geometry::HAIR) ? static_cast<Hair *>(geom) : NULL;
-  Mesh *mesh = (geom->type == Geometry::MESH) ? static_cast<Mesh *>(geom) : NULL;
-
   /* Compares curve_keys rather than strands in order to handle quick hair
    * adjustments in dynamic BVH - other methods could probably do this better. */
   array<float3> oldcurve_keys;
   array<float> oldcurve_radius;
-  array<int> oldtriangles;
-  if (hair) {
-    oldcurve_keys.steal_data(hair->curve_keys);
-    oldcurve_radius.steal_data(hair->curve_radius);
-  }
-  else {
-    oldtriangles.steal_data(mesh->triangles);
-  }
+  oldcurve_keys.steal_data(hair->curve_keys);
+  oldcurve_radius.steal_data(hair->curve_radius);
 
-  geom->clear();
-  geom->used_shaders = used_shaders;
+  hair->clear();
+  hair->used_shaders = used_shaders;
 
   if (view_layer.use_hair && scene->curve_system_manager->use_curves) {
 #ifdef WITH_NEW_OBJECT_TYPES
@@ -1377,35 +879,31 @@ void BlenderSync::sync_hair(BL::Depsgraph b_depsgraph,
 #endif
     {
       /* Particle hair. */
-      bool need_undeformed = geom->need_attribute(scene, ATTR_STD_GENERATED);
+      bool need_undeformed = hair->need_attribute(scene, ATTR_STD_GENERATED);
       BL::Mesh b_mesh = object_to_mesh(
           b_data, b_ob, b_depsgraph, need_undeformed, Mesh::SUBDIVISION_NONE);
 
       if (b_mesh) {
-        sync_particle_hair(geom, b_mesh, b_ob, false);
+        sync_particle_hair(hair, b_mesh, b_ob, false);
         free_object_to_mesh(b_data, b_ob, b_mesh);
       }
     }
   }
 
   /* tag update */
-  const bool rebuild = (hair && ((oldcurve_keys != hair->curve_keys) ||
-                                 (oldcurve_radius != hair->curve_radius))) ||
-                       (mesh && (oldtriangles != mesh->triangles));
+  const bool rebuild = ((oldcurve_keys != hair->curve_keys) ||
+                        (oldcurve_radius != hair->curve_radius));
 
-  geom->tag_update(scene, rebuild);
+  hair->tag_update(scene, rebuild);
 }
 
 void BlenderSync::sync_hair_motion(BL::Depsgraph b_depsgraph,
                                    BL::Object b_ob,
-                                   Geometry *geom,
+                                   Hair *hair,
                                    int motion_step)
 {
-  Hair *hair = (geom->type == Geometry::HAIR) ? static_cast<Hair *>(geom) : NULL;
-  Mesh *mesh = (geom->type == Geometry::MESH) ? static_cast<Mesh *>(geom) : NULL;
-
   /* Skip if nothing exported. */
-  if ((hair && hair->num_keys() == 0) || (mesh && mesh->verts.size() == 0)) {
+  if (hair->num_keys() == 0) {
     return;
   }
 
@@ -1424,7 +922,7 @@ void BlenderSync::sync_hair_motion(BL::Depsgraph b_depsgraph,
       /* Particle hair. */
       BL::Mesh b_mesh = object_to_mesh(b_data, b_ob, b_depsgraph, false, Mesh::SUBDIVISION_NONE);
       if (b_mesh) {
-        sync_particle_hair(geom, b_mesh, b_ob, true, motion_step);
+        sync_particle_hair(hair, b_mesh, b_ob, true, motion_step);
         free_object_to_mesh(b_data, b_ob, b_mesh);
         return;
       }
@@ -1432,12 +930,7 @@ void BlenderSync::sync_hair_motion(BL::Depsgraph b_depsgraph,
   }
 
   /* No deformation on this frame, copy coordinates if other frames did have it. */
-  if (hair) {
-    hair->copy_center_to_motion_step(motion_step);
-  }
-  else {
-    mesh->copy_center_to_motion_step(motion_step);
-  }
+  hair->copy_center_to_motion_step(motion_step);
 }
 
 CCL_NAMESPACE_END
diff --git a/intern/cycles/blender/blender_geometry.cpp b/intern/cycles/blender/blender_geometry.cpp
index 7ca35cff961..7d63899cb99 100644
--- a/intern/cycles/blender/blender_geometry.cpp
+++ b/intern/cycles/blender/blender_geometry.cpp
@@ -41,15 +41,11 @@ Geometry *BlenderSync::sync_geometry(BL::Depsgraph &b_depsgraph,
   Shader *default_shader = (b_ob.type() == BL::Object::type_VOLUME) ? scene->default_volume :
                                                                       scene->default_surface;
 #ifdef WITH_NEW_OBJECT_TYPES
-  Geometry::Type geom_type = ((b_ob.type() == BL::Object::type_HAIR || use_particle_hair) &&
-                              (scene->curve_system_manager->primitive != CURVE_TRIANGLES)) ?
+  Geometry::Type geom_type = (b_ob.type() == BL::Object::type_HAIR || use_particle_hair) ?
                                  Geometry::HAIR :
                                  Geometry::MESH;
 #else
-  Geometry::Type geom_type = ((use_particle_hair) &&
-                              (scene->curve_system_manager->primitive != CURVE_TRIANGLES)) ?
-                                 Geometry::HAIR :
-                                 Geometry::MESH;
+  Geometry::Type geom_type = (use_particle_hair) ? Geometry::HAIR : Geometry::MESH;
 #endif
 
   /* Find shader indices. */
@@ -134,7 +130,8 @@ Geometry *BlenderSync::sync_geometry(BL::Depsgraph &b_depsgraph,
 #else
   if (use_particle_hair) {
 #endif
-    sync_hair(b_depsgraph, b_ob, geom, used_shaders);
+    Hair *hair = static_cast<Hair *>(geom);
+    sync_hair(b_depsgraph, b_ob, hair, used_shaders);
   }
   else if (b_ob.type() == BL::Object::type_VOLUME || object_fluid_gas_domain_find(b_ob)) {
     Mesh *mesh = static_cast<Mesh *>(geom);
@@ -178,7 +175,8 @@ void BlenderSync::sync_geometry_motion(BL::Depsgraph &b_depsgraph,
 #else
   if (use_particle_hair) {
 #endif
-    sync_hair_motion(b_depsgraph, b_ob, geom, motion_step);
+    Hair *hair = static_cast<Hair *>(geom);
+    sync_hair_motion(b_depsgraph, b_ob, hair, motion_step);
   }
   else if (b_ob.type() == BL::Object::type_VOLUME || object_fluid_gas_domain_find(b_ob)) {
     /* No volume motion blur support yet. */
diff --git a/intern/cycles/blender/blender_sync.h b/intern/cycles/blender/blender_sync.h
index 341281b18ee..3c39cfd9446 100644
--- a/intern/cycles/blender/blender_sync.h
+++ b/intern/cycles/blender/blender_sync.h
@@ -153,15 +153,12 @@ class BlenderSync {
   /* Hair */
   void sync_hair(BL::Depsgraph b_depsgraph,
                  BL::Object b_ob,
-                 Geometry *geom,
+                 Hair *hair,
                  const vector<Shader *> &used_shaders);
-  void sync_hair_motion(BL::Depsgraph b_depsgraph,
-                        BL::Object b_ob,
-                        Geometry *geom,
-                        int motion_step);
+  void sync_hair_motion(BL::Depsgraph b_depsgraph, BL::Object b_ob, Hair *hair, int motion_step);
   void sync_hair(Hair *hair, BL::Object &b_ob, bool motion, int motion_step = 0);
   void sync_particle_hair(
-      Geometry *geom, BL::Mesh &b_mesh, BL::Object &b_ob, bool motion, int motion_step = 0);
+      Hair *hair, BL::Mesh &b_mesh, BL::Object &b_ob, bool motion, int motion_step = 0);
   void sync_curve_settings(BL::Depsgraph &b_depsgraph);
   bool object_has_particle_hair(BL::Object b_ob);