Sculpt: Refactor draw manager sculpt drawing mechanism

Workbench/Eevee now displays multiple multi-materials correctly.

Iterate over pbvh nodes when doing object iteration. This makes the
rendering process more streamlined and allow for using different materials.

This change will make possible to:
- Add culling pass of each pbvh leaf node. (speedup if zoomed on a small
area)
- Reduce number of lead node iteration.
- Reduce code complexity

1 files changed, 41 insertions, 65 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_materials.c b/source/blender/draw/engines/eevee/eevee_materials.c
index c6a523e4822..8ee5b51d825 100644
--- a/source/blender/draw/engines/eevee/eevee_materials.c
+++ b/source/blender/draw/engines/eevee/eevee_materials.c
@@ -1190,17 +1190,12 @@ void EEVEE_materials_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
 
 #define ADD_SHGROUP_CALL(shgrp, ob, ma, geom, oedata) \
   do { \
-    if (is_sculpt_mode_draw) { \
-      DRW_shgroup_call_sculpt_add(shgrp, ob, ob->obmat); \
+    if (oedata) { \
+      DRW_shgroup_call_object_add_with_callback( \
+          shgrp, geom, ob, ma, EEVEE_lightprobes_obj_visibility_cb, oedata); \
     } \
     else { \
-      if (oedata) { \
-        DRW_shgroup_call_object_add_with_callback( \
-            shgrp, geom, ob, ma, EEVEE_lightprobes_obj_visibility_cb, oedata); \
-      } \
-      else { \
-        DRW_shgroup_call_object_add_ex(shgrp, geom, ob, ma, false); \
-      } \
+      DRW_shgroup_call_object_add_ex(shgrp, geom, ob, ma, false); \
     } \
   } while (0)
 
@@ -1604,6 +1599,16 @@ static void material_transparent(Material *ma,
   }
 }
 
+/* Return correct material or &defmaterial if slot is empty. */
+BLI_INLINE Material *eevee_object_material_get(Object *ob, int slot)
+{
+  Material *ma = give_current_material(ob, slot + 1);
+  if (ma == NULL) {
+    ma = &defmaterial;
+  }
+  return ma;
+}
+
 void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
                                     EEVEE_ViewLayerData *sldata,
                                     Object *ob,
@@ -1617,15 +1622,14 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
 
   const bool do_cull = (draw_ctx->v3d &&
                         (draw_ctx->v3d->shading.flag & V3D_SHADING_BACKFACE_CULLING));
-  const bool is_sculpt_mode = DRW_object_use_pbvh_drawing(ob);
+  bool is_sculpt_mode = DRW_object_use_pbvh_drawing(ob);
   /* For now just force fully shaded with eevee when supported. */
-  const bool is_sculpt_mode_draw = ob->sculpt && ob->sculpt->pbvh &&
-                                   BKE_pbvh_type(ob->sculpt->pbvh) != PBVH_FACES;
-  const bool is_default_mode_shader = is_sculpt_mode;
+  is_sculpt_mode = is_sculpt_mode &&
+                   !(ob->sculpt->pbvh && BKE_pbvh_type(ob->sculpt->pbvh) == PBVH_FACES);
 
   /* First get materials for this mesh. */
   if (ELEM(ob->type, OB_MESH, OB_CURVE, OB_SURF, OB_FONT, OB_MBALL)) {
-    const int materials_len = MAX2(1, (is_sculpt_mode_draw ? 1 : ob->totcol));
+    const int materials_len = MAX2(1, ob->totcol);
 
     struct DRWShadingGroup **shgrp_array = BLI_array_alloca(shgrp_array, materials_len);
     struct DRWShadingGroup **shgrp_depth_array = BLI_array_alloca(shgrp_depth_array,
@@ -1635,40 +1639,22 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
 
     struct GPUMaterial **gpumat_array = BLI_array_alloca(gpumat_array, materials_len);
     struct GPUMaterial **gpumat_depth_array = BLI_array_alloca(gpumat_array, materials_len);
+    struct Material **ma_array = BLI_array_alloca(ma_array, materials_len);
 
     bool use_flat_nor = false;
-
-    if (is_default_mode_shader) {
-      if (is_sculpt_mode_draw) {
-        use_flat_nor = DRW_object_is_flat_normal(ob);
-      }
-    }
-
     for (int i = 0; i < materials_len; ++i) {
-      Material *ma;
-
-      if (is_sculpt_mode_draw) {
-        ma = NULL;
-      }
-      else {
-        ma = give_current_material(ob, i + 1);
-      }
-
+      ma_array[i] = eevee_object_material_get(ob, i);
       gpumat_array[i] = NULL;
       gpumat_depth_array[i] = NULL;
       shgrp_array[i] = NULL;
       shgrp_depth_array[i] = NULL;
       shgrp_depth_clip_array[i] = NULL;
 
-      if (ma == NULL) {
-        ma = &defmaterial;
-      }
-
-      switch (ma->blend_method) {
+      switch (ma_array[i]->blend_method) {
         case MA_BM_SOLID:
         case MA_BM_CLIP:
         case MA_BM_HASHED:
-          material_opaque(ma,
+          material_opaque(ma_array[i],
                           material_hash,
                           sldata,
                           vedata,
@@ -1683,7 +1669,7 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
         case MA_BM_ADD:
         case MA_BM_MULTIPLY:
         case MA_BM_BLEND:
-          material_transparent(ma,
+          material_transparent(ma_array[i],
                                sldata,
                                vedata,
                                do_cull,
@@ -1725,17 +1711,18 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
                                                          &auto_layer_count);
       }
 
-      if (is_sculpt_mode_draw || mat_geom) {
+      if (is_sculpt_mode) {
+        /* TODO(fclem): Support Vcol. */
+        DRW_shgroup_call_sculpt_with_materials_add(shgrp_array, ma_array, ob, false);
+        DRW_shgroup_call_sculpt_with_materials_add(shgrp_depth_array, ma_array, ob, false);
+        DRW_shgroup_call_sculpt_with_materials_add(shgrp_depth_clip_array, ma_array, ob, false);
+        /* TODO(fclem): Support shadows in sculpt mode. */
+      }
+      else if (mat_geom) {
         for (int i = 0; i < materials_len; ++i) {
-          if (!is_sculpt_mode_draw && mat_geom[i] == NULL) {
+          if (mat_geom[i] == NULL) {
             continue;
           }
-          EEVEE_ObjectEngineData *oedata = NULL;
-          Material *ma = give_current_material(ob, i + 1);
-
-          if (ma == NULL) {
-            ma = &defmaterial;
-          }
 
           /* Do not render surface if we are rendering a volume object
            * and do not have a surface closure. */
@@ -1746,23 +1733,16 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
 
           /* XXX TODO rewrite this to include the dupli objects.
            * This means we cannot exclude dupli objects from reflections!!! */
+          EEVEE_ObjectEngineData *oedata = NULL;
           if ((ob->base_flag & BASE_FROM_DUPLI) == 0) {
             oedata = EEVEE_object_data_ensure(ob);
             oedata->ob = ob;
             oedata->test_data = &sldata->probes->vis_data;
           }
 
-          /* Shading pass */
-          ADD_SHGROUP_CALL(shgrp_array[i], ob, ma, mat_geom[i], oedata);
-
-          /* Depth Prepass */
-          ADD_SHGROUP_CALL_SAFE(shgrp_depth_array[i], ob, ma, mat_geom[i], oedata);
-          ADD_SHGROUP_CALL_SAFE(shgrp_depth_clip_array[i], ob, ma, mat_geom[i], oedata);
-
-          /* TODO(fclem): Don't support shadows in sculpt mode. */
-          if (is_sculpt_mode_draw) {
-            break;
-          }
+          ADD_SHGROUP_CALL(shgrp_array[i], ob, ma_array[i], mat_geom[i], oedata);
+          ADD_SHGROUP_CALL_SAFE(shgrp_depth_array[i], ob, ma_array[i], mat_geom[i], oedata);
+          ADD_SHGROUP_CALL_SAFE(shgrp_depth_clip_array[i], ob, ma_array[i], mat_geom[i], oedata);
 
           char *name = auto_layer_names;
           for (int j = 0; j < auto_layer_count; ++j) {
@@ -1785,19 +1765,19 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata,
 
           /* Shadow Pass */
           struct GPUMaterial *gpumat;
-          switch (ma->blend_shadow) {
+          switch (ma_array[i]->blend_shadow) {
             case MA_BS_SOLID:
               EEVEE_lights_cache_shcaster_add(sldata, stl, mat_geom[i], ob);
               *cast_shadow = true;
               break;
             case MA_BS_CLIP:
-              gpumat = EEVEE_material_mesh_depth_get(scene, ma, false, true);
+              gpumat = EEVEE_material_mesh_depth_get(scene, ma_array[i], false, true);
               EEVEE_lights_cache_shcaster_material_add(
-                  sldata, psl, gpumat, mat_geom[i], ob, &ma->alpha_threshold);
+                  sldata, psl, gpumat, mat_geom[i], ob, &ma_array[i]->alpha_threshold);
               *cast_shadow = true;
               break;
             case MA_BS_HASHED:
-              gpumat = EEVEE_material_mesh_depth_get(scene, ma, true, true);
+              gpumat = EEVEE_material_mesh_depth_get(scene, ma_array[i], true, true);
               EEVEE_lights_cache_shcaster_material_add(sldata, psl, gpumat, mat_geom[i], ob, NULL);
               *cast_shadow = true;
               break;
@@ -1845,11 +1825,7 @@ void EEVEE_hair_cache_populate(EEVEE_Data *vedata,
         }
 
         DRWShadingGroup *shgrp = NULL;
-        Material *ma = give_current_material(ob, part->omat);
-
-        if (ma == NULL) {
-          ma = &defmaterial;
-        }
+        Material *ma = eevee_object_material_get(ob, part->omat - 1);
 
         float *color_p = &ma->r;
         float *metal_p = &ma->metallic;