Cleanup: Use const variables for object's evaluated mesh

Generally the evaluated mesh should not be changed, since that is the
job of the modifier stack. Current code is far from const correct in
that regard. This commit uses a const variable for the reult of
`BKE_object_get_evaluated_mesh` in some cases. The most common
remaining case is retrieving a BVH tree from the mesh.

7 files changed, 29 insertions, 26 deletions

diff --git a/source/blender/blenkernel/BKE_object.h b/source/blender/blenkernel/BKE_object.h
index af9f5d7bf22..cd66f026828 100644
--- a/source/blender/blenkernel/BKE_object.h
+++ b/source/blender/blenkernel/BKE_object.h
@@ -243,7 +243,7 @@ void BKE_object_dimensions_set(struct Object *ob, const float value[3], int axis
 
 void BKE_object_empty_draw_type_set(struct Object *ob, const int value);
 void BKE_object_boundbox_flag(struct Object *ob, int flag, const bool set);
-void BKE_object_boundbox_calc_from_mesh(struct Object *ob, struct Mesh *me_eval);
+void BKE_object_boundbox_calc_from_mesh(struct Object *ob, const struct Mesh *me_eval);
 void BKE_object_minmax(struct Object *ob, float r_min[3], float r_max[3], const bool use_hidden);
 bool BKE_object_minmax_dupli(struct Depsgraph *depsgraph,
                              struct Scene *scene,
diff --git a/source/blender/blenkernel/intern/constraint.c b/source/blender/blenkernel/intern/constraint.c
index ca03c9c3de4..193b6d82d03 100644
--- a/source/blender/blenkernel/intern/constraint.c
+++ b/source/blender/blenkernel/intern/constraint.c
@@ -470,7 +470,7 @@ static void contarget_get_mesh_mat(Object *ob, const char *substring, float mat[
   /* when not in EditMode, use the 'final' evaluated mesh, depsgraph
    * ensures we build with CD_MDEFORMVERT layer
    */
-  Mesh *me_eval = BKE_object_get_evaluated_mesh(ob);
+  const Mesh *me_eval = BKE_object_get_evaluated_mesh(ob);
   BMEditMesh *em = BKE_editmesh_from_object(ob);
   float plane[3];
   float imat[3][3], tmat[3][3];
@@ -488,17 +488,17 @@ static void contarget_get_mesh_mat(Object *ob, const char *substring, float mat[
   float normal[3] = {0.0f, 0.0f, 0.0f};
   float weightsum = 0.0f;
   if (me_eval) {
-    MDeformVert *dvert = CustomData_get_layer(&me_eval->vdata, CD_MDEFORMVERT);
+    const MDeformVert *dvert = CustomData_get_layer(&me_eval->vdata, CD_MDEFORMVERT);
     int numVerts = me_eval->totvert;
 
     /* check that dvert is a valid pointers (just in case) */
     if (dvert) {
-      MDeformVert *dv = dvert;
-      MVert *mv = me_eval->mvert;
 
       /* get the average of all verts with that are in the vertex-group */
-      for (int i = 0; i < numVerts; i++, dv++, mv++) {
-        MDeformWeight *dw = BKE_defvert_find_index(dv, defgroup);
+      for (int i = 0; i < numVerts; i++) {
+        const MDeformVert *dv = &dvert[i];
+        const MVert *mv = &me_eval->mvert[i];
+        const MDeformWeight *dw = BKE_defvert_find_index(dv, defgroup);
 
         if (dw && dw->weight > 0.0f) {
           float nor[3];
diff --git a/source/blender/blenkernel/intern/displist.cc b/source/blender/blenkernel/intern/displist.cc
index cfe4701fb69..a4ffaa8b10b 100644
--- a/source/blender/blenkernel/intern/displist.cc
+++ b/source/blender/blenkernel/intern/displist.cc
@@ -1694,7 +1694,7 @@ static void boundbox_displist_object(Object *ob)
       ob->runtime.bb = (BoundBox *)MEM_callocN(sizeof(BoundBox), __func__);
     }
 
-    Mesh *mesh_eval = BKE_object_get_evaluated_mesh(ob);
+    const Mesh *mesh_eval = BKE_object_get_evaluated_mesh(ob);
     if (mesh_eval) {
       BKE_object_boundbox_calc_from_mesh(ob, mesh_eval);
     }
diff --git a/source/blender/blenkernel/intern/effect.c b/source/blender/blenkernel/intern/effect.c
index 97aba5e787d..1b628b16802 100644
--- a/source/blender/blenkernel/intern/effect.c
+++ b/source/blender/blenkernel/intern/effect.c
@@ -716,7 +716,7 @@ int get_effector_data(EffectorCache *eff,
   }
   else if (eff->pd && eff->pd->shape == PFIELD_SHAPE_POINTS) {
     /* TODO: hair and points object support */
-    Mesh *me_eval = BKE_object_get_evaluated_mesh(eff->ob);
+    const Mesh *me_eval = BKE_object_get_evaluated_mesh(eff->ob);
     if (me_eval != NULL) {
       copy_v3_v3(efd->loc, me_eval->mvert[*efd->index].co);
       normal_short_to_float_v3(efd->nor, me_eval->mvert[*efd->index].no);
@@ -830,7 +830,7 @@ static void get_effector_tot(
 
   if (eff->pd->shape == PFIELD_SHAPE_POINTS) {
     /* TODO: hair and points object support */
-    Mesh *me_eval = BKE_object_get_evaluated_mesh(eff->ob);
+    const Mesh *me_eval = BKE_object_get_evaluated_mesh(eff->ob);
     *tot = me_eval != NULL ? me_eval->totvert : 1;
 
     if (*tot && eff->pd->forcefield == PFIELD_HARMONIC && point->index >= 0) {
diff --git a/source/blender/blenkernel/intern/gpencil_geom.c b/source/blender/blenkernel/intern/gpencil_geom.c
index 53939da08e2..077c1a65243 100644
--- a/source/blender/blenkernel/intern/gpencil_geom.c
+++ b/source/blender/blenkernel/intern/gpencil_geom.c
@@ -2480,9 +2480,9 @@ bool BKE_gpencil_convert_mesh(Main *bmain,
 
   /* Use evaluated data to get mesh with all modifiers on top. */
   Object *ob_eval = (Object *)DEG_get_evaluated_object(depsgraph, ob_mesh);
-  Mesh *me_eval = BKE_object_get_evaluated_mesh(ob_eval);
-  MPoly *mp, *mpoly = me_eval->mpoly;
-  MLoop *mloop = me_eval->mloop;
+  const Mesh *me_eval = BKE_object_get_evaluated_mesh(ob_eval);
+  const MPoly *mpoly = me_eval->mpoly;
+  const MLoop *mloop = me_eval->mloop;
   int mpoly_len = me_eval->totpoly;
   char element_name[200];
 
@@ -2515,8 +2515,9 @@ bool BKE_gpencil_convert_mesh(Main *bmain,
       bGPDframe *gpf_fill = BKE_gpencil_layer_frame_get(
           gpl_fill, CFRA + frame_offset, GP_GETFRAME_ADD_NEW);
       int i;
-      for (i = 0, mp = mpoly; i < mpoly_len; i++, mp++) {
-        MLoop *ml = &mloop[mp->loopstart];
+      for (i = 0; i < mpoly_len; i++) {
+        const MPoly *mp = &mpoly[i];
+
         /* Find material. */
         int mat_idx = 0;
         Material *ma = BKE_object_material_get(ob_mesh, mp->mat_nr + 1);
@@ -2539,8 +2540,10 @@ bool BKE_gpencil_convert_mesh(Main *bmain,
         gps_fill->flag |= GP_STROKE_CYCLIC;
 
         /* Add points to strokes. */
-        for (int j = 0; j < mp->totloop; j++, ml++) {
-          MVert *mv = &me_eval->mvert[ml->v];
+        for (int j = 0; j < mp->totloop; j++) {
+          const MLoop *ml = &mloop[mp->loopstart + j];
+          const MVert *mv = &me_eval->mvert[ml->v];
+
           bGPDspoint *pt = &gps_fill->points[j];
           copy_v3_v3(&pt->x, mv->co);
           mul_m4_v3(matrix, &pt->x);
diff --git a/source/blender/blenkernel/intern/object.c b/source/blender/blenkernel/intern/object.c
index a5e16172e75..ff5d94d20b7 100644
--- a/source/blender/blenkernel/intern/object.c
+++ b/source/blender/blenkernel/intern/object.c
@@ -3860,7 +3860,7 @@ void BKE_object_boundbox_flag(Object *ob, int flag, const bool set)
   }
 }
 
-void BKE_object_boundbox_calc_from_mesh(struct Object *ob, struct Mesh *me_eval)
+void BKE_object_boundbox_calc_from_mesh(struct Object *ob, const struct Mesh *me_eval)
 {
   float min[3], max[3];
 
@@ -4169,7 +4169,7 @@ void BKE_object_foreach_display_point(Object *ob,
                                       void *user_data)
 {
   /* TODO: pointcloud and hair objects support */
-  Mesh *mesh_eval = BKE_object_get_evaluated_mesh(ob);
+  const Mesh *mesh_eval = BKE_object_get_evaluated_mesh(ob);
   float co[3];
 
   if (mesh_eval != NULL) {
diff --git a/source/blender/blenkernel/intern/object_dupli.cc b/source/blender/blenkernel/intern/object_dupli.cc
index 768fa9373c1..77969328365 100644
--- a/source/blender/blenkernel/intern/object_dupli.cc
+++ b/source/blender/blenkernel/intern/object_dupli.cc
@@ -335,14 +335,14 @@ static void make_child_duplis(const DupliContext *ctx,
 /** \name Internal Data Access Utilities
  * \{ */
 
-static Mesh *mesh_data_from_duplicator_object(Object *ob,
-                                              BMEditMesh **r_em,
-                                              const float (**r_vert_coords)[3],
-                                              const float (**r_vert_normals)[3])
+static const Mesh *mesh_data_from_duplicator_object(Object *ob,
+                                                    BMEditMesh **r_em,
+                                                    const float (**r_vert_coords)[3],
+                                                    const float (**r_vert_normals)[3])
 {
   /* Gather mesh info. */
   BMEditMesh *em = BKE_editmesh_from_object(ob);
-  Mesh *me_eval;
+  const Mesh *me_eval;
 
   *r_em = nullptr;
   *r_vert_coords = nullptr;
@@ -603,7 +603,7 @@ static void make_duplis_verts(const DupliContext *ctx)
   BMEditMesh *em = nullptr;
   const float(*vert_coords)[3] = nullptr;
   const float(*vert_normals)[3] = nullptr;
-  Mesh *me_eval = mesh_data_from_duplicator_object(
+  const Mesh *me_eval = mesh_data_from_duplicator_object(
       parent, &em, &vert_coords, use_rotation ? &vert_normals : nullptr);
   if (em == nullptr && me_eval == nullptr) {
     return;
@@ -1151,7 +1151,7 @@ static void make_duplis_faces(const DupliContext *ctx)
   /* Gather mesh info. */
   BMEditMesh *em = nullptr;
   const float(*vert_coords)[3] = nullptr;
-  Mesh *me_eval = mesh_data_from_duplicator_object(parent, &em, &vert_coords, nullptr);
+  const Mesh *me_eval = mesh_data_from_duplicator_object(parent, &em, &vert_coords, nullptr);
   if (em == nullptr && me_eval == nullptr) {
     return;
   }