Cleanup: Use const when retrieving custom data layers

Knowing when layers are retrieved for write access will be essential
when adding proper copy-on-write support. This commit makes that
clearer by adding `const` where the retrieved data is not modified.

Ref T95842

8 files changed, 19 insertions, 18 deletions

diff --git a/source/blender/draw/intern/draw_cache_impl_subdivision.cc b/source/blender/draw/intern/draw_cache_impl_subdivision.cc
index 8eb0509d615..cfdf059ca37 100644
--- a/source/blender/draw/intern/draw_cache_impl_subdivision.cc
+++ b/source/blender/draw/intern/draw_cache_impl_subdivision.cc
@@ -745,8 +745,8 @@ struct DRWCacheBuildingContext {
   /* Origindex layers from the mesh to directly look up during traversal the origindex from the
    * base mesh for edit data so that we do not have to handle yet another GPU buffer and do this in
    * the shaders. */
-  int *v_origindex;
-  int *e_origindex;
+  const int *v_origindex;
+  const int *e_origindex;
 };
 
 static bool draw_subdiv_topology_info_cb(const SubdivForeachContext *foreach_context,
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh.h b/source/blender/draw/intern/mesh_extractors/extract_mesh.h
index d55386dfd7d..b88cd9e77d2 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh.h
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh.h
@@ -67,7 +67,7 @@ typedef struct MeshRenderData {
   const float (*bm_poly_normals)[3];
   const float (*bm_poly_centers)[3];
 
-  int *v_origindex, *e_origindex, *p_origindex;
+  const int *v_origindex, *e_origindex, *p_origindex;
   int edge_crease_ofs;
   int vert_crease_ofs;
   int bweight_ofs;
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_edituv_stretch_angle.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_edituv_stretch_angle.cc
index 4ced14ab11a..14f61dcd739 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_edituv_stretch_angle.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_edituv_stretch_angle.cc
@@ -26,7 +26,7 @@ struct UVStretchAngle {
 
 struct MeshExtract_StretchAngle_Data {
   UVStretchAngle *vbo_data;
-  MLoopUV *luv;
+  const MLoopUV *luv;
   float auv[2][2], last_auv[2];
   float av[2][3], last_av[3];
   int cd_ofs;
@@ -98,7 +98,7 @@ static void extract_edituv_stretch_angle_init(const MeshRenderData *mr,
   }
   else {
     BLI_assert(ELEM(mr->extract_type, MR_EXTRACT_MAPPED, MR_EXTRACT_MESH));
-    data->luv = (MLoopUV *)CustomData_get_layer(&mr->me->ldata, CD_MLOOPUV);
+    data->luv = (const MLoopUV *)CustomData_get_layer(&mr->me->ldata, CD_MLOOPUV);
   }
 }
 
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_fdots_uv.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_fdots_uv.cc
index 26f0b07f676..e7a3cb03903 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_fdots_uv.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_fdots_uv.cc
@@ -17,7 +17,7 @@ namespace blender::draw {
 
 struct MeshExtract_FdotUV_Data {
   float (*vbo_data)[2];
-  MLoopUV *uv_data;
+  const MLoopUV *uv_data;
   int cd_ofs;
 };
 
@@ -49,7 +49,7 @@ static void extract_fdots_uv_init(const MeshRenderData *mr,
     data->cd_ofs = CustomData_get_offset(&mr->bm->ldata, CD_MLOOPUV);
   }
   else {
-    data->uv_data = (MLoopUV *)CustomData_get_layer(&mr->me->ldata, CD_MLOOPUV);
+    data->uv_data = (const MLoopUV *)CustomData_get_layer(&mr->me->ldata, CD_MLOOPUV);
   }
 }
 
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_orco.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_orco.cc
index ed1a0ccd178..b45a73a27c0 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_orco.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_orco.cc
@@ -17,7 +17,7 @@ namespace blender::draw {
 
 struct MeshExtract_Orco_Data {
   float (*vbo_data)[4];
-  float (*orco)[3];
+  const float (*orco)[3];
 };
 
 static void extract_orco_init(const MeshRenderData *mr,
@@ -42,7 +42,7 @@ static void extract_orco_init(const MeshRenderData *mr,
 
   MeshExtract_Orco_Data *data = static_cast<MeshExtract_Orco_Data *>(tls_data);
   data->vbo_data = (float(*)[4])GPU_vertbuf_get_data(vbo);
-  data->orco = static_cast<float(*)[3]>(CustomData_get_layer(cd_vdata, CD_ORCO));
+  data->orco = static_cast<const float(*)[3]>(CustomData_get_layer(cd_vdata, CD_ORCO));
   /* Make sure `orco` layer was requested only if needed! */
   BLI_assert(data->orco);
 }
@@ -105,7 +105,7 @@ static void extract_orco_init_subdiv(const DRWSubdivCache *subdiv_cache,
   float(*coarse_vbo_data)[4] = static_cast<float(*)[4]>(GPU_vertbuf_get_data(coarse_vbo));
 
   CustomData *cd_vdata = &mr->me->vdata;
-  float(*orco)[3] = static_cast<float(*)[3]>(CustomData_get_layer(cd_vdata, CD_ORCO));
+  const float(*orco)[3] = static_cast<const float(*)[3]>(CustomData_get_layer(cd_vdata, CD_ORCO));
 
   if (mr->extract_type == MR_EXTRACT_MESH) {
     const MLoop *mloop = mr->mloop;
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_pos_nor.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_pos_nor.cc
index ea46d9c4caa..c8c91d45542 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_pos_nor.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_pos_nor.cc
@@ -220,7 +220,7 @@ static void extract_pos_nor_init_subdiv(const DRWSubdivCache *subdiv_cache,
 
   if (subdiv_cache->use_custom_loop_normals) {
     Mesh *coarse_mesh = subdiv_cache->mesh;
-    float(*lnors)[3] = static_cast<float(*)[3]>(
+    const float(*lnors)[3] = static_cast<float(*)[3]>(
         CustomData_get_layer(&coarse_mesh->ldata, CD_NORMAL));
     BLI_assert(lnors != nullptr);
 
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_sculpt_data.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_sculpt_data.cc
index 96595df9276..5658ed85c8b 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_sculpt_data.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_sculpt_data.cc
@@ -42,8 +42,8 @@ static void extract_sculpt_data_init(const MeshRenderData *mr,
   CustomData *cd_vdata = (mr->extract_type == MR_EXTRACT_BMESH) ? &mr->bm->vdata : &mr->me->vdata;
   CustomData *cd_pdata = (mr->extract_type == MR_EXTRACT_BMESH) ? &mr->bm->pdata : &mr->me->pdata;
 
-  float *cd_mask = (float *)CustomData_get_layer(cd_vdata, CD_PAINT_MASK);
-  int *cd_face_set = (int *)CustomData_get_layer(cd_pdata, CD_SCULPT_FACE_SETS);
+  const float *cd_mask = (const float *)CustomData_get_layer(cd_vdata, CD_PAINT_MASK);
+  const int *cd_face_set = (const int *)CustomData_get_layer(cd_pdata, CD_SCULPT_FACE_SETS);
 
   GPU_vertbuf_init_with_format(vbo, format);
   GPU_vertbuf_data_alloc(vbo, mr->loop_len);
@@ -54,7 +54,7 @@ static void extract_sculpt_data_init(const MeshRenderData *mr,
   };
 
   gpuSculptData *vbo_data = (gpuSculptData *)GPU_vertbuf_get_data(vbo);
-  MLoop *loops = (MLoop *)CustomData_get_layer(cd_ldata, CD_MLOOP);
+  const MLoop *loops = (const MLoop *)CustomData_get_layer(cd_ldata, CD_MLOOP);
 
   if (mr->extract_type == MR_EXTRACT_BMESH) {
     int cd_mask_ofs = CustomData_get_offset(cd_vdata, CD_PAINT_MASK);
@@ -126,7 +126,7 @@ static void extract_sculpt_data_init_subdiv(const DRWSubdivCache *subdiv_cache,
   /* First, interpolate mask if available. */
   GPUVertBuf *mask_vbo = nullptr;
   GPUVertBuf *subdiv_mask_vbo = nullptr;
-  float *cd_mask = (float *)CustomData_get_layer(cd_vdata, CD_PAINT_MASK);
+  const float *cd_mask = (const float *)CustomData_get_layer(cd_vdata, CD_PAINT_MASK);
 
   if (cd_mask) {
     GPUVertFormat mask_format = {0};
@@ -167,7 +167,7 @@ static void extract_sculpt_data_init_subdiv(const DRWSubdivCache *subdiv_cache,
   };
 
   gpuFaceSet *face_sets = (gpuFaceSet *)GPU_vertbuf_get_data(face_set_vbo);
-  int *cd_face_set = (int *)CustomData_get_layer(cd_pdata, CD_SCULPT_FACE_SETS);
+  const int *cd_face_set = (const int *)CustomData_get_layer(cd_pdata, CD_SCULPT_FACE_SETS);
 
   GPUVertFormat *format = get_sculpt_data_format();
   GPU_vertbuf_init_build_on_device(vbo, format, subdiv_cache->num_subdiv_loops);
diff --git a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_tan.cc b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_tan.cc
index 25f78d68914..91cd675d32f 100644
--- a/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_tan.cc
+++ b/source/blender/draw/intern/mesh_extractors/extract_mesh_vbo_tan.cc
@@ -291,7 +291,8 @@ static void extract_tan_init_subdiv(const DRWSubdivCache *subdiv_cache,
   for (int i = 0; i < tan_len; i++) {
     float(*tan_data)[4] = (float(*)[4])GPU_vertbuf_get_data(coarse_vbo);
     const char *name = tangent_names[i];
-    float(*layer_data)[4] = (float(*)[4])CustomData_get_layer_named(&loop_data, CD_TANGENT, name);
+    const float(*layer_data)[4] = (float(*)[4])CustomData_get_layer_named(
+        &loop_data, CD_TANGENT, name);
     for (int ml_index = 0; ml_index < mr->loop_len; ml_index++) {
       copy_v3_v3(*tan_data, layer_data[ml_index]);
       (*tan_data)[3] = (layer_data[ml_index][3] > 0.0f) ? 1.0f : -1.0f;
@@ -306,7 +307,7 @@ static void extract_tan_init_subdiv(const DRWSubdivCache *subdiv_cache,
   }
   if (use_orco_tan) {
     float(*tan_data)[4] = (float(*)[4])GPU_vertbuf_get_data(coarse_vbo);
-    float(*layer_data)[4] = (float(*)[4])CustomData_get_layer_n(&loop_data, CD_TANGENT, 0);
+    const float(*layer_data)[4] = (float(*)[4])CustomData_get_layer_n(&loop_data, CD_TANGENT, 0);
     for (int ml_index = 0; ml_index < mr->loop_len; ml_index++) {
       copy_v3_v3(*tan_data, layer_data[ml_index]);
       (*tan_data)[3] = (layer_data[ml_index][3] > 0.0f) ? 1.0f : -1.0f;