Cleanup: Use const pointers in PBVH draw arguments

Also remove two unused variables

source/blender/draw/DRW_pbvh.hh

@@ -39,15 +39,17 @@ struct PBVH_GPU_Args {
   blender::OffsetIndices<int> faces;
   blender::Span<int> corner_verts;
   blender::Span<int> corner_edges;
-  int mesh_faces_num, mesh_grids_num;
-  CustomData *vdata, *ldata, *pdata;
+  int mesh_grids_num;
+  const CustomData *vdata;
+  const CustomData *ldata;
+  const CustomData *pdata;
   blender::Span<blender::float3> vert_normals;
 
   const char *active_color;
   const char *render_color;
 
   int face_sets_color_seed, face_sets_color_default;
-  int *face_sets; /* for PBVH_FACES and PBVH_GRIDS */
+  const int *face_sets; /* for PBVH_FACES and PBVH_GRIDS */
 
   SubdivCCG *subdiv_ccg;
   const DMFlagMat *grid_flag_mats;
@@ -57,13 +59,11 @@ struct PBVH_GPU_Args {
   void **gridfaces;
   BLI_bitmap **grid_hidden;
 
-  int *prim_indices;
+  const int *prim_indices;
   int totprim;
 
   const bool *hide_poly;
 
-  int node_verts_num;
-
   const MLoopTri *mlooptri;
   const int *looptri_faces;
   PBVHNode *node;

source/blender/draw/intern/draw_pbvh.cc

@@ -154,7 +154,7 @@ struct PBVHBatch {
   }
 };
 
-static CustomData *get_cdata(eAttrDomain domain, PBVH_GPU_Args *args)
+static const CustomData *get_cdata(eAttrDomain domain, const PBVH_GPU_Args *args)
 {
   switch (domain) {
     case ATTR_DOMAIN_POINT:
@@ -443,7 +443,7 @@ struct PBVHBatches {
         break;
 
       case CD_PBVH_FSET_TYPE: {
-        int *face_sets = args->face_sets;
+        const int *face_sets = args->face_sets;
 
         if (!face_sets) {
           uchar white[3] = {UCHAR_MAX, UCHAR_MAX, UCHAR_MAX};
@@ -902,7 +902,7 @@ struct PBVHBatches {
     }
 
     if (need_aliases) {
-      CustomData *cdata = get_cdata(domain, args);
+      const CustomData *cdata = get_cdata(domain, args);
       int layer_i = cdata ? CustomData_get_named_layer_index(
                                 cdata, eCustomDataType(type), name.c_str()) :
                             -1;