1 files changed, 59 insertions, 16 deletions

diff --git a/source/blender/draw/engines/basic/basic_engine.c b/source/blender/draw/engines/basic/basic_engine.c
index c120df7e897..87f5c6f5857 100644
--- a/source/blender/draw/engines/basic/basic_engine.c
+++ b/source/blender/draw/engines/basic/basic_engine.c
@@ -25,9 +25,12 @@
 
 #include "DRW_render.h"
 
+#include "BKE_object.h"
 #include "BKE_paint.h"
 #include "BKE_particle.h"
 
+#include "BLI_alloca.h"
+
 #include "DNA_particle_types.h"
 
 #include "GPU_shader.h"
@@ -80,6 +83,7 @@ typedef struct BASIC_PrivateData {
   DRWShadingGroup *depth_shgrp[2];
   DRWShadingGroup *depth_shgrp_cull[2];
   DRWShadingGroup *depth_hair_shgrp[2];
+  bool use_material_slot_selection;
 } BASIC_PrivateData; /* Transient data */
 
 /* Functions */
@@ -131,6 +135,8 @@ static void basic_cache_init(void *vedata)
     stl->g_data = MEM_callocN(sizeof(*stl->g_data), __func__);
   }
 
+  stl->g_data->use_material_slot_selection = DRW_state_is_material_select();
+
   /* Twice for normal and in front objects. */
   for (int i = 0; i < 2; i++) {
     DRWState clip_state = (draw_ctx->sh_cfg == GPU_SHADER_CFG_CLIPPED) ? DRW_STATE_CLIP_PLANES : 0;
@@ -155,6 +161,38 @@ static void basic_cache_init(void *vedata)
   }
 }
 
+/* TODO(fclem): DRW_cache_object_surface_material_get needs a refactor to allow passing NULL
+ * instead of gpumat_array. Avoiding all this boilerplate code. */
+static struct GPUBatch **basic_object_surface_material_get(Object *ob)
+{
+  const int materials_len = DRW_cache_object_material_count_get(ob);
+  struct GPUMaterial **gpumat_array = BLI_array_alloca(gpumat_array, materials_len);
+  memset(gpumat_array, 0, sizeof(*gpumat_array) * materials_len);
+
+  return DRW_cache_object_surface_material_get(ob, gpumat_array, materials_len);
+}
+
+static void basic_cache_populate_particles(void *vedata, Object *ob)
+{
+  const bool do_in_front = (ob->dtx & OB_DRAW_IN_FRONT) != 0;
+  BASIC_StorageList *stl = ((BASIC_Data *)vedata)->stl;
+  for (ParticleSystem *psys = ob->particlesystem.first; psys != NULL; psys = psys->next) {
+    if (!DRW_object_is_visible_psys_in_active_context(ob, psys)) {
+      continue;
+    }
+    ParticleSettings *part = psys->part;
+    const int draw_as = (part->draw_as == PART_DRAW_REND) ? part->ren_as : part->draw_as;
+    if (draw_as == PART_DRAW_PATH) {
+      struct GPUBatch *hairs = DRW_cache_particles_get_hair(ob, psys, NULL);
+      if (stl->g_data->use_material_slot_selection) {
+        const short material_slot = part->omat;
+        DRW_select_load_id(ob->runtime.select_id | (material_slot << 16));
+      }
+      DRW_shgroup_call(stl->g_data->depth_hair_shgrp[do_in_front], hairs, NULL);
+    }
+  }
+}
+
 static void basic_cache_populate(void *vedata, Object *ob)
 {
   BASIC_StorageList *stl = ((BASIC_Data *)vedata)->stl;
@@ -165,24 +203,13 @@ static void basic_cache_populate(void *vedata, Object *ob)
     return;
   }
 
-  bool do_in_front = (ob->dtx & OB_DRAW_IN_FRONT) != 0;
-
   const DRWContextState *draw_ctx = DRW_context_state_get();
   if (ob != draw_ctx->object_edit) {
-    for (ParticleSystem *psys = ob->particlesystem.first; psys != NULL; psys = psys->next) {
-      if (!DRW_object_is_visible_psys_in_active_context(ob, psys)) {
-        continue;
-      }
-      ParticleSettings *part = psys->part;
-      const int draw_as = (part->draw_as == PART_DRAW_REND) ? part->ren_as : part->draw_as;
-      if (draw_as == PART_DRAW_PATH) {
-        struct GPUBatch *hairs = DRW_cache_particles_get_hair(ob, psys, NULL);
-        DRW_shgroup_call(stl->g_data->depth_hair_shgrp[do_in_front], hairs, NULL);
-      }
-    }
+    basic_cache_populate_particles(vedata, ob);
   }
 
   /* Make flat object selectable in ortho view if wireframe is enabled. */
+  const bool do_in_front = (ob->dtx & OB_DRAW_IN_FRONT) != 0;
   if ((draw_ctx->v3d->overlay.flag & V3D_OVERLAY_WIREFRAMES) ||
       (draw_ctx->v3d->shading.type == OB_WIRE) || (ob->dtx & OB_DRAWWIRE) || (ob->dt == OB_WIRE)) {
     int flat_axis = 0;
@@ -211,9 +238,25 @@ static void basic_cache_populate(void *vedata, Object *ob)
     DRW_shgroup_call_sculpt(shgrp, ob, false, false);
   }
   else {
-    struct GPUBatch *geom = DRW_cache_object_surface_get(ob);
-    if (geom) {
-      DRW_shgroup_call(shgrp, geom, ob);
+    if (stl->g_data->use_material_slot_selection && BKE_object_supports_material_slots(ob)) {
+      struct GPUBatch **geoms = basic_object_surface_material_get(ob);
+      if (geoms) {
+        const int materials_len = DRW_cache_object_material_count_get(ob);
+        for (int i = 0; i < materials_len; i++) {
+          if (geoms[i] == NULL) {
+            continue;
+          }
+          const short material_slot_select_id = i + 1;
+          DRW_select_load_id(ob->runtime.select_id | (material_slot_select_id << 16));
+          DRW_shgroup_call(shgrp, geoms[i], ob);
+        }
+      }
+    }
+    else {
+      struct GPUBatch *geom = DRW_cache_object_surface_get(ob);
+      if (geom) {
+        DRW_shgroup_call(shgrp, geom, ob);
+      }
     }
   }
 }