Refactor: Evaluate surface objects as mesh components

This commit furthers some of the changes that were started in
rBb9febb54a492 and subsequent commits by changing the way surface
objects are presented to render engines and other users of evaluated
objects in the same way. Instead of presenting evaluated surface objects
as an `OB_SURF` object with an evaluated mesh, `OB_SURF` objects
can now have an evaluated geometry set, which uses the same system
as other object types to deal with multi-type evaluated data.

This clarification makes it more obvious that lots of code that dealt
with the `DispList` type isn't used. It wasn't before either, now it's
just *by design*. Over 1100 lines can be removed. The legacy curve
draw cache code is much simpler now too. The idea behind the further
removal of `DispList` is that it's better to focus optimization efforts
on a single mesh data structure.

One expected functional change is that the evaluated mesh from surface
objects can now be used in geometry nodes with the object info node.

Cycles and the OBJ IO tests had to be tweaked to avoid using evaluated
surface objects instead of the newly exposed mesh objects.

Differential Revision: https://developer.blender.org/D14550

2 files changed, 8 insertions, 280 deletions

diff --git a/source/blender/blenkernel/intern/displist.cc b/source/blender/blenkernel/intern/displist.cc
index 791e0faab3b..cda2bb5f4c0 100644
--- a/source/blender/blenkernel/intern/displist.cc
+++ b/source/blender/blenkernel/intern/displist.cc
@@ -948,12 +948,11 @@ static void displist_surf_indices(DispList *dl)
   }
 }
 
-static void evaluate_surface_object(Depsgraph *depsgraph,
-                                    const Scene *scene,
-                                    Object *ob,
-                                    const bool for_render,
-                                    ListBase *r_dispbase,
-                                    Mesh **r_final)
+static GeometrySet evaluate_surface_object(Depsgraph *depsgraph,
+                                           const Scene *scene,
+                                           Object *ob,
+                                           const bool for_render,
+                                           ListBase *r_dispbase)
 {
   BLI_assert(ob->type == OB_SURF);
   const Curve *cu = (const Curve *)ob->data;
@@ -1036,8 +1035,7 @@ static void evaluate_surface_object(Depsgraph *depsgraph,
   if (!geometry_set.has_mesh()) {
     geometry_set.replace_mesh(BKE_mesh_new_nomain(0, 0, 0, 0, 0));
   }
-  MeshComponent &mesh_component = geometry_set.get_component_for_write<MeshComponent>();
-  *r_final = mesh_component.release();
+  return geometry_set;
 }
 
 static void rotateBevelPiece(const Curve *cu,
@@ -1483,9 +1481,8 @@ void BKE_displist_make_curveTypes(Depsgraph *depsgraph,
   ListBase *dispbase = &ob->runtime.curve_cache->disp;
 
   if (ob->type == OB_SURF) {
-    Mesh *mesh_eval;
-    evaluate_surface_object(depsgraph, scene, ob, for_render, dispbase, &mesh_eval);
-    BKE_object_eval_assign_data(ob, &mesh_eval->id, true);
+    GeometrySet geometry = evaluate_surface_object(depsgraph, scene, ob, for_render, dispbase);
+    ob->runtime.geometry_set_eval = new GeometrySet(std::move(geometry));
   }
   else {
     GeometrySet geometry = evaluate_curve_type_object(depsgraph, scene, ob, for_render, dispbase);
diff --git a/source/blender/blenkernel/intern/displist_tangent.c b/source/blender/blenkernel/intern/displist_tangent.c
deleted file mode 100644
index eb6bdd8d5e9..00000000000
--- a/source/blender/blenkernel/intern/displist_tangent.c
+++ /dev/null
@@ -1,269 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-
-/** \file
- * \ingroup bke
- */
-
-#include "BLI_math.h"
-#include "BLI_task.h"
-
-#include "BKE_displist.h"
-#include "BKE_displist_tangent.h"
-
-#include "MEM_guardedalloc.h"
-
-/* interface */
-#include "mikktspace.h"
-
-/* -------------------------------------------------------------------- */
-/** \name Internal Types
- * \{ */
-
-typedef struct {
-  const DispList *dl;
-  float (*tangent)[4]; /* destination */
-  /** Face normal for flat shading. */
-  float (*fnormals)[3];
-  /** Use by surfaces. Size of the surface in faces. */
-  int u_len, v_len;
-} SGLSLDisplistToTangent;
-
-/** \} */
-
-/* ---------------------------------------------------------------------- */
-/** \name DL_INDEX3 tangents
- * \{ */
-
-static int dl3_ts_GetNumFaces(const SMikkTSpaceContext *pContext)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-
-  return dlt->dl->parts;
-}
-
-static int dl3_ts_GetNumVertsOfFace(const SMikkTSpaceContext *pContext, const int face_num)
-{
-  UNUSED_VARS(pContext, face_num);
-
-  return 3;
-}
-
-static void dl3_ts_GetPosition(const SMikkTSpaceContext *pContext,
-                               float r_co[3],
-                               const int face_num,
-                               const int vert_index)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-  const float(*verts)[3] = (float(*)[3])dlt->dl->verts;
-  const int(*idx)[3] = (int(*)[3])dlt->dl->index;
-
-  copy_v3_v3(r_co, verts[idx[face_num][vert_index]]);
-}
-
-static void dl3_ts_GetTextureCoordinate(const SMikkTSpaceContext *pContext,
-                                        float r_uv[2],
-                                        const int face_num,
-                                        const int vert_index)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-  const int(*idx)[3] = (int(*)[3])dlt->dl->index;
-
-  r_uv[0] = idx[face_num][vert_index] / (float)(dlt->dl->nr - 1);
-  r_uv[1] = 0.0f;
-}
-
-static void dl3_ts_GetNormal(const SMikkTSpaceContext *pContext,
-                             float r_no[3],
-                             const int face_num,
-                             const int vert_index)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-  UNUSED_VARS(face_num, vert_index);
-
-  copy_v3_v3(r_no, dlt->dl->nors);
-}
-
-static void dl3_ts_SetTSpace(const SMikkTSpaceContext *pContext,
-                             const float fvTangent[3],
-                             const float fSign,
-                             const int face_num,
-                             const int vert_index)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-  UNUSED_VARS(face_num, vert_index);
-
-  copy_v3_v3(dlt->tangent[0], fvTangent);
-  dlt->tangent[0][3] = fSign;
-}
-
-/** \} */
-
-/* ---------------------------------------------------------------------- */
-/** \name DL_SURF tangents
- * \{ */
-
-static int dlsurf_ts_GetNumFaces(const SMikkTSpaceContext *pContext)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-
-  return dlt->v_len * dlt->u_len;
-}
-
-static int dlsurf_ts_GetNumVertsOfFace(const SMikkTSpaceContext *pContext, const int face_num)
-{
-  UNUSED_VARS(pContext, face_num);
-
-  return 4;
-}
-
-static int face_to_vert_index(SGLSLDisplistToTangent *dlt,
-                              const int face_num,
-                              const int vert_index)
-{
-  int u = face_num % dlt->u_len;
-  int v = face_num / dlt->u_len;
-
-  if (vert_index == 0) {
-    u += 1;
-  }
-  else if (vert_index == 1) {
-    u += 1;
-    v += 1;
-  }
-  else if (vert_index == 2) {
-    v += 1;
-  }
-
-  /* Cyclic correction. */
-  u = u % dlt->dl->nr;
-  v = v % dlt->dl->parts;
-
-  return v * dlt->dl->nr + u;
-}
-
-static void dlsurf_ts_GetPosition(const SMikkTSpaceContext *pContext,
-                                  float r_co[3],
-                                  const int face_num,
-                                  const int vert_index)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-  const float(*verts)[3] = (float(*)[3])dlt->dl->verts;
-
-  copy_v3_v3(r_co, verts[face_to_vert_index(dlt, face_num, vert_index)]);
-}
-
-static void dlsurf_ts_GetTextureCoordinate(const SMikkTSpaceContext *pContext,
-                                           float r_uv[2],
-                                           const int face_num,
-                                           const int vert_index)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-
-  int idx = face_to_vert_index(dlt, face_num, vert_index);
-
-  /* NOTE: For some reason the shading U and V are swapped compared to the
-   * one described in the surface format. */
-  r_uv[0] = (idx / dlt->dl->nr) / (float)(dlt->v_len);
-  r_uv[1] = (idx % dlt->dl->nr) / (float)(dlt->u_len);
-
-  if (r_uv[0] == 0.0f && ELEM(vert_index, 1, 2)) {
-    r_uv[0] = 1.0f;
-  }
-  if (r_uv[1] == 0.0f && ELEM(vert_index, 0, 1)) {
-    r_uv[1] = 1.0f;
-  }
-}
-
-static void dlsurf_ts_GetNormal(const SMikkTSpaceContext *pContext,
-                                float r_no[3],
-                                const int face_num,
-                                const int vert_index)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-  const float(*nors)[3] = (float(*)[3])dlt->dl->nors;
-
-  if (dlt->fnormals) {
-    copy_v3_v3(r_no, dlt->fnormals[face_num]);
-  }
-  else {
-    copy_v3_v3(r_no, nors[face_to_vert_index(dlt, face_num, vert_index)]);
-  }
-}
-
-static void dlsurf_ts_SetTSpace(const SMikkTSpaceContext *pContext,
-                                const float fvTangent[3],
-                                const float fSign,
-                                const int face_num,
-                                const int vert_index)
-{
-  SGLSLDisplistToTangent *dlt = pContext->m_pUserData;
-  UNUSED_VARS(face_num, vert_index);
-
-  float *r_tan = dlt->tangent[face_num * 4 + vert_index];
-  copy_v3_v3(r_tan, fvTangent);
-  r_tan[3] = fSign;
-}
-
-/** \} */
-
-/* ---------------------------------------------------------------------- */
-/** \name Entry point
- * \{ */
-
-void BKE_displist_tangent_calc(const DispList *dl, float (*fnormals)[3], float (**r_tangent)[4])
-{
-  if (dl->type == DL_INDEX3) {
-    /* INDEX3 have only one tangent so we don't need actual allocation. */
-    BLI_assert(*r_tangent != NULL);
-
-    SGLSLDisplistToTangent mesh2tangent = {
-        .tangent = *r_tangent,
-        .dl = dl,
-    };
-    SMikkTSpaceContext sContext = {NULL};
-    SMikkTSpaceInterface sInterface = {NULL};
-    sContext.m_pUserData = &mesh2tangent;
-    sContext.m_pInterface = &sInterface;
-    sInterface.m_getNumFaces = dl3_ts_GetNumFaces;
-    sInterface.m_getNumVerticesOfFace = dl3_ts_GetNumVertsOfFace;
-    sInterface.m_getPosition = dl3_ts_GetPosition;
-    sInterface.m_getTexCoord = dl3_ts_GetTextureCoordinate;
-    sInterface.m_getNormal = dl3_ts_GetNormal;
-    sInterface.m_setTSpaceBasic = dl3_ts_SetTSpace;
-    /* 0 if failed */
-    genTangSpaceDefault(&sContext);
-  }
-  else if (dl->type == DL_SURF) {
-    SGLSLDisplistToTangent mesh2tangent = {
-        .dl = dl,
-        .u_len = dl->nr - ((dl->flag & DL_CYCL_U) ? 0 : 1),
-        .v_len = dl->parts - ((dl->flag & DL_CYCL_V) ? 0 : 1),
-        .fnormals = fnormals,
-    };
-
-    int loop_len = mesh2tangent.u_len * mesh2tangent.v_len * 4;
-
-    if (*r_tangent == NULL) {
-      *r_tangent = MEM_mallocN(sizeof(float[4]) * loop_len, "displist tangents");
-    }
-    mesh2tangent.tangent = *r_tangent;
-    SMikkTSpaceContext sContext = {NULL};
-    SMikkTSpaceInterface sInterface = {NULL};
-    sContext.m_pUserData = &mesh2tangent;
-    sContext.m_pInterface = &sInterface;
-    sInterface.m_getNumFaces = dlsurf_ts_GetNumFaces;
-    sInterface.m_getNumVerticesOfFace = dlsurf_ts_GetNumVertsOfFace;
-    sInterface.m_getPosition = dlsurf_ts_GetPosition;
-    sInterface.m_getTexCoord = dlsurf_ts_GetTextureCoordinate;
-    sInterface.m_getNormal = dlsurf_ts_GetNormal;
-    sInterface.m_setTSpaceBasic = dlsurf_ts_SetTSpace;
-    /* 0 if failed */
-    genTangSpaceDefault(&sContext);
-  }
-  else {
-    /* Unsupported. */
-    BLI_assert(0);
-  }
-}
-
-/** \} */