Workbench: Refactor: Add Shadow support

16 files changed, 364 insertions, 95 deletions

diff --git a/source/blender/draw/engines/workbench/shaders/workbench_composite_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_composite_frag.glsl
index 0616043aef0..cdb9823096c 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_composite_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_composite_frag.glsl
@@ -38,5 +38,7 @@ void main()
   fragColor.rgb = base_color;
 #endif
 
+  fragColor.rgb *= get_shadow(N);
+
   fragColor.a = 1.0;
 }
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_data_lib.glsl b/source/blender/draw/engines/workbench/shaders/workbench_data_lib.glsl
index 83ee73b00d8..75fde40bc94 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_data_lib.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_data_lib.glsl
@@ -9,6 +9,11 @@ struct WorldData {
   vec4 viewport_size;
   vec4 object_outline_color;
   vec4 shadow_direction_vs;
+  float shadow_focus;
+  float shadow_shift;
+  float shadow_mul;
+  float shadow_add;
+  /* - 16 bytes alignment-  */
   LightData lights[4];
   vec4 ambient_color;
   int matcap_orientation;
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_shadow_debug_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_shadow_debug_frag.glsl
index 6b0741b6d1b..6fa76510e6e 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_shadow_debug_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_shadow_debug_frag.glsl
@@ -1,15 +1,19 @@
 
 out vec4 fragColor;
 
+layout(location = 0) out vec4 materialData;
+layout(location = 1) out vec4 normalData;
+layout(location = 2) out uint objectId;
+
 void main()
 {
-  const float intensity = 0.25;
+  const float a = 0.25;
 #ifdef SHADOW_PASS
-  fragColor = vec4(
-      (gl_FrontFacing) ? vec3(intensity, -intensity, 0.0) : vec3(-intensity, intensity, 0.0), 1.0);
+  materialData.rgb = gl_FrontFacing ? vec3(a, -a, 0.0) : vec3(-a, a, 0.0);
 #else
-  fragColor = vec4((gl_FrontFacing) ? vec3(intensity, intensity, -intensity) :
-                                      vec3(-intensity, -intensity, intensity),
-                   1.0);
+  materialData.rgb = gl_FrontFacing ? vec3(a, a, -a) : vec3(-a, -a, a);
 #endif
+  materialData.a = 0.0;
+  normalData = vec4(0.0);
+  objectId = 0u;
 }
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_transparent_accum_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_transparent_accum_frag.glsl
index e1b031e7294..7113b998fa7 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_transparent_accum_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_transparent_accum_frag.glsl
@@ -79,6 +79,8 @@ void main()
   vec3 shaded_color = color;
 #endif
 
+  shaded_color *= get_shadow(N);
+
   /* Listing 4 */
   float weight = calculate_transparent_weight() * alpha_interp;
   transparentAccum = vec4(shaded_color * weight, alpha_interp);
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_world_light_lib.glsl b/source/blender/draw/engines/workbench/shaders/workbench_world_light_lib.glsl
index e7c94c9b955..1c966a9e47c 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_world_light_lib.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_world_light_lib.glsl
@@ -121,3 +121,13 @@ vec3 get_world_lighting(vec3 base_color, float roughness, float metallic, vec3 N
 
   return diffuse_light + specular_light;
 }
+
+uniform bool forceShadowing = false;
+
+float get_shadow(vec3 N)
+{
+  float light_factor = -dot(N, world_data.shadow_direction_vs.xyz);
+  float shadow_mix = smoothstep(world_data.shadow_shift, world_data.shadow_focus, light_factor);
+  shadow_mix *= forceShadowing ? 0.0 : world_data.shadow_mul;
+  return shadow_mix + world_data.shadow_add;
+}
\ No newline at end of file
diff --git a/source/blender/draw/engines/workbench/workbench_data.c b/source/blender/draw/engines/workbench/workbench_data.c
index ad5eaff2392..937c6a33319 100644
--- a/source/blender/draw/engines/workbench/workbench_data.c
+++ b/source/blender/draw/engines/workbench/workbench_data.c
@@ -79,17 +79,44 @@ static WORKBENCH_ViewLayerData *workbench_view_layer_data_ensure_ex(struct ViewL
   return *vldata;
 }
 
-static void workbench_world_data_update_shadow_direction_vs(WORKBENCH_PrivateData *wpd)
+void workbench_private_data_get_light_direction(float r_light_direction[3])
 {
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+  Scene *scene = draw_ctx->scene;
+
+  copy_v3_v3(r_light_direction, scene->display.light_direction);
+  SWAP(float, r_light_direction[2], r_light_direction[1]);
+  r_light_direction[2] = -r_light_direction[2];
+  r_light_direction[0] = -r_light_direction[0];
+}
+
+static void workbench_shadow_world_data_update(WORKBENCH_PrivateData *wpd)
+{
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+  const Scene *scene = draw_ctx->scene;
+
   WORKBENCH_UBO_World *wd = &wpd->world_data;
-  float light_direction[3];
   float view_matrix[4][4];
   DRW_view_viewmat_get(NULL, view_matrix, false);
 
-  workbench_private_data_get_light_direction(light_direction);
+  workbench_private_data_get_light_direction(wpd->light_direction_ws);
 
   /* Shadow direction. */
-  mul_v3_mat3_m4v3(wd->shadow_direction_vs, view_matrix, light_direction);
+  mul_v3_mat3_m4v3(wd->shadow_direction_vs, view_matrix, wpd->light_direction_ws);
+
+  /* Clamp to avoid overshadowing and shading errors. */
+  float focus = clamp_f(scene->display.shadow_focus, 0.0001f, 0.99999f);
+  wd->shadow_shift = scene->display.shadow_shift;
+  wd->shadow_focus = 1.0f - focus * (1.0f - wd->shadow_shift);
+
+  if (SHADOW_ENABLED(wpd)) {
+    wd->shadow_mul = wpd->shading.shadow_intensity;
+    wd->shadow_add = 1.0f - wd->shadow_mul;
+  }
+  else {
+    wd->shadow_mul = 0.0f;
+    wd->shadow_add = 1.0f;
+  }
 }
 
 /* \} */
@@ -205,13 +232,6 @@ void workbench_private_data_init(WORKBENCH_PrivateData *wpd)
     wpd->studio_light = BKE_studiolight_find(wpd->shading.studio_light, STUDIOLIGHT_TYPE_STUDIO);
   }
 
-  float shadow_focus = scene->display.shadow_focus;
-  /* Clamp to avoid overshadowing and shading errors. */
-  CLAMP(shadow_focus, 0.0001f, 0.99999f);
-  wpd->shadow_shift = scene->display.shadow_shift;
-  wpd->shadow_focus = 1.0f - shadow_focus * (1.0f - wpd->shadow_shift);
-  wpd->shadow_multiplier = 1.0 - wpd->shading.shadow_intensity;
-
   WORKBENCH_UBO_World *wd = &wpd->world_data;
   wd->matcap_orientation = (wpd->shading.flag & V3D_SHADING_MATCAP_FLIP_X) != 0;
 
@@ -227,7 +247,7 @@ void workbench_private_data_init(WORKBENCH_PrivateData *wpd)
   wd->curvature_ridge = 0.5f / max_ff(SQUARE(wpd->shading.curvature_ridge_factor), 1e-4f);
   wd->curvature_valley = 0.7f / max_ff(SQUARE(wpd->shading.curvature_valley_factor), 1e-4f);
 
-  workbench_world_data_update_shadow_direction_vs(wpd);
+  workbench_shadow_world_data_update(wpd);
   workbench_viewvecs_update(wpd->world_data.viewvecs);
   copy_v2_v2(wpd->world_data.viewport_size, DRW_viewport_size_get());
   copy_v2_v2(wpd->world_data.viewport_size_inv, DRW_viewport_invert_size_get());
@@ -296,17 +316,6 @@ void workbench_private_data_init(WORKBENCH_PrivateData *wpd)
   BLI_listbase_clear(&wpd->smoke_domains);
 }
 
-void workbench_private_data_get_light_direction(float r_light_direction[3])
-{
-  const DRWContextState *draw_ctx = DRW_context_state_get();
-  Scene *scene = draw_ctx->scene;
-
-  copy_v3_v3(r_light_direction, scene->display.light_direction);
-  SWAP(float, r_light_direction[2], r_light_direction[1]);
-  r_light_direction[2] = -r_light_direction[2];
-  r_light_direction[0] = -r_light_direction[0];
-}
-
 void workbench_update_material_ubos(WORKBENCH_PrivateData *UNUSED(wpd))
 {
   const DRWContextState *draw_ctx = DRW_context_state_get();
diff --git a/source/blender/draw/engines/workbench/workbench_deferred.c b/source/blender/draw/engines/workbench/workbench_deferred.c
index f1528c2213c..4bd0e663650 100644
--- a/source/blender/draw/engines/workbench/workbench_deferred.c
+++ b/source/blender/draw/engines/workbench/workbench_deferred.c
@@ -334,12 +334,6 @@ static struct GPUTexture *create_jitter_texture(int num_samples)
 }
 /* Functions */
 
-static void workbench_init_object_data(DrawData *dd)
-{
-  WORKBENCH_ObjectData *data = (WORKBENCH_ObjectData *)dd;
-  data->shadow_bbox_dirty = true;
-}
-
 static void workbench_init_oit_framebuffer(WORKBENCH_FramebufferList *fbl,
                                            DefaultTextureList *dtxl)
 {
@@ -732,7 +726,7 @@ void workbench_deferred_cache_init(WORKBENCH_Data *vedata)
   /* Deferred Mix Pass */
   {
     workbench_private_data_get_light_direction(e_data.display.light_direction);
-    studiolight_update_light(wpd, e_data.display.light_direction);
+    studiolight_update_light(wpd);
 
     if (SHADOW_ENABLED(wpd)) {
       psl->composite_pass = DRW_pass_create(
@@ -1161,11 +1155,7 @@ void workbench_deferred_solid_cache_populate(WORKBENCH_Data *vedata, Object *ob)
         }
         else {
           WORKBENCH_ObjectData *engine_object_data = (WORKBENCH_ObjectData *)DRW_drawdata_ensure(
-              &ob->id,
-              &draw_engine_workbench_solid,
-              sizeof(WORKBENCH_ObjectData),
-              &workbench_init_object_data,
-              NULL);
+              &ob->id, &draw_engine_workbench_solid, sizeof(WORKBENCH_ObjectData), NULL, NULL);
 
           if (studiolight_object_cast_visible_shadow(wpd, ob, engine_object_data)) {
 
diff --git a/source/blender/draw/engines/workbench/workbench_engine.c b/source/blender/draw/engines/workbench/workbench_engine.c
index 06a8508c997..ac0a4e6221a 100644
--- a/source/blender/draw/engines/workbench/workbench_engine.c
+++ b/source/blender/draw/engines/workbench/workbench_engine.c
@@ -82,6 +82,7 @@ static void workbench_cache_init(void *ved)
 
   workbench_opaque_cache_init(vedata);
   workbench_transparent_cache_init(vedata);
+  workbench_shadow_cache_init(vedata);
 
   //   workbench_aa_create_pass(vedata);
   //   workbench_dof_create_pass(vedata);
@@ -105,14 +106,14 @@ static void workbench_cache_sculpt_populate(WORKBENCH_PrivateData *wpd, Object *
   BLI_assert(wpd->shading.color_type != V3D_SHADING_TEXTURE_COLOR);
 
   if (use_single_drawcall) {
-    DRWShadingGroup *grp = workbench_material_setup(wpd, ob, 0, color_type, false);
+    DRWShadingGroup *grp = workbench_material_setup(wpd, ob, 0, color_type, NULL);
     DRW_shgroup_call_sculpt(grp, ob, false, false, use_vcol);
   }
   else {
     const int materials_len = DRW_cache_object_material_count_get(ob);
     struct DRWShadingGroup **shgrps = BLI_array_alloca(shgrps, materials_len);
     for (int i = 0; i < materials_len; i++) {
-      shgrps[i] = workbench_material_setup(wpd, ob, i + 1, color_type, false);
+      shgrps[i] = workbench_material_setup(wpd, ob, i + 1, color_type, NULL);
     }
     DRW_shgroup_call_sculpt_with_materials(shgrps, ob, false);
   }
@@ -132,7 +133,7 @@ static void workbench_cache_texpaint_populate(WORKBENCH_PrivateData *wpd, Object
       int interp = (imapaint->interp == IMAGEPAINT_INTERP_LINEAR) ? SHD_INTERP_LINEAR :
                                                                     SHD_INTERP_CLOSEST;
 
-      DRWShadingGroup *grp = workbench_image_setup(wpd, ob, 0, ima, NULL, interp, false);
+      DRWShadingGroup *grp = workbench_image_setup(wpd, ob, 0, ima, NULL, interp);
       DRW_shgroup_call(grp, geom, ob);
     }
   }
@@ -141,14 +142,17 @@ static void workbench_cache_texpaint_populate(WORKBENCH_PrivateData *wpd, Object
     if (geoms) {
       const int materials_len = DRW_cache_object_material_count_get(ob);
       for (int i = 0; i < materials_len; i++) {
-        DRWShadingGroup *grp = workbench_image_setup(wpd, ob, i + 1, NULL, NULL, 0, false);
+        DRWShadingGroup *grp = workbench_image_setup(wpd, ob, i + 1, NULL, NULL, 0);
         DRW_shgroup_call(grp, geoms[i], ob);
       }
     }
   }
 }
 
-static void workbench_cache_common_populate(WORKBENCH_PrivateData *wpd, Object *ob, int color_type)
+static void workbench_cache_common_populate(WORKBENCH_PrivateData *wpd,
+                                            Object *ob,
+                                            int color_type,
+                                            bool *r_transp)
 {
   const bool use_tex = ELEM(color_type, V3D_SHADING_TEXTURE_COLOR);
   const bool use_vcol = ELEM(color_type, V3D_SHADING_VERTEX_COLOR);
@@ -159,7 +163,7 @@ static void workbench_cache_common_populate(WORKBENCH_PrivateData *wpd, Object *
     struct GPUBatch *geom = (use_vcol) ? DRW_cache_mesh_surface_vertpaint_get(ob) :
                                          DRW_cache_object_surface_get(ob);
     if (geom) {
-      DRWShadingGroup *grp = workbench_material_setup(wpd, ob, 0, color_type, false);
+      DRWShadingGroup *grp = workbench_material_setup(wpd, ob, 0, color_type, r_transp);
       DRW_shgroup_call(grp, geom, ob);
     }
   }
@@ -169,7 +173,7 @@ static void workbench_cache_common_populate(WORKBENCH_PrivateData *wpd, Object *
     if (geoms) {
       const int materials_len = DRW_cache_object_material_count_get(ob);
       for (int i = 0; i < materials_len; i++) {
-        DRWShadingGroup *grp = workbench_material_setup(wpd, ob, i + 1, color_type, false);
+        DRWShadingGroup *grp = workbench_material_setup(wpd, ob, i + 1, color_type, r_transp);
         DRW_shgroup_call(grp, geoms[i], ob);
       }
     }
@@ -192,8 +196,8 @@ static void workbench_cache_hair_populate(WORKBENCH_PrivateData *wpd,
   int interp = (imapaint && imapaint->interp == IMAGEPAINT_INTERP_LINEAR) ? SHD_INTERP_LINEAR :
                                                                             SHD_INTERP_CLOSEST;
   DRWShadingGroup *grp = (use_texpaint_mode) ?
-                             workbench_image_setup(wpd, ob, part->omat, ima, NULL, interp, true) :
-                             workbench_material_setup(wpd, ob, part->omat, color_type, true);
+                             workbench_image_hair_setup(wpd, ob, part->omat, ima, NULL, interp) :
+                             workbench_material_hair_setup(wpd, ob, part->omat, color_type);
 
   DRW_shgroup_hair_create_sub(ob, psys, md, grp);
 }
@@ -203,7 +207,8 @@ static void workbench_cache_hair_populate(WORKBENCH_PrivateData *wpd,
 static int workbench_color_type_get(WORKBENCH_PrivateData *wpd,
                                     Object *ob,
                                     bool *r_sculpt_pbvh,
-                                    bool *r_texpaint_mode)
+                                    bool *r_texpaint_mode,
+                                    bool *r_draw_shadow)
 {
   int color_type = wpd->shading.color_type;
   const Mesh *me = (ob->type == OB_MESH) ? ob->data : NULL;
@@ -241,6 +246,20 @@ static int workbench_color_type_get(WORKBENCH_PrivateData *wpd,
     }
   }
 
+  if (r_draw_shadow) {
+    *r_draw_shadow = (ob->dtx & OB_DRAW_NO_SHADOW_CAST) == 0 && SHADOW_ENABLED(wpd);
+    /* Currently unsupported in sculpt mode. We could revert to the slow
+     * method in this case but I'm not sure if it's a good idea given that
+     * sculpted meshes are heavy to begin with. */
+    if (is_sculpt_pbvh) {
+      *r_draw_shadow = false;
+    }
+
+    if (is_active && DRW_object_use_hide_faces(ob)) {
+      *r_draw_shadow = false;
+    }
+  }
+
   return color_type;
 }
 
@@ -256,9 +275,9 @@ static void workbench_cache_populate(void *ved, Object *ob)
 
   if (ob->type == OB_MESH && ob->modifiers.first != NULL) {
     bool use_sculpt_pbvh, use_texpaint_mode;
-    int color_type = workbench_color_type_get(wpd, ob, &use_sculpt_pbvh, &use_texpaint_mode);
+    int color_type = workbench_color_type_get(wpd, ob, &use_sculpt_pbvh, &use_texpaint_mode, NULL);
 
-    for (ModifierData *md = ob->modifiers.first; md; md = md->next) {
+    LISTBASE_FOREACH (ModifierData *, md, &ob->modifiers) {
       if (md->type != eModifierType_ParticleSystem) {
         continue;
       }
@@ -286,8 +305,9 @@ static void workbench_cache_populate(void *ved, Object *ob)
   }
 
   if (ELEM(ob->type, OB_MESH, OB_CURVE, OB_SURF, OB_FONT, OB_MBALL)) {
-    bool use_sculpt_pbvh, use_texpaint_mode;
-    int color_type = workbench_color_type_get(wpd, ob, &use_sculpt_pbvh, &use_texpaint_mode);
+    bool use_sculpt_pbvh, use_texpaint_mode, draw_shadow, has_transp_mat = false;
+    int color_type = workbench_color_type_get(
+        wpd, ob, &use_sculpt_pbvh, &use_texpaint_mode, &draw_shadow);
 
     if (use_sculpt_pbvh) {
       workbench_cache_sculpt_populate(wpd, ob, color_type);
@@ -296,7 +316,11 @@ static void workbench_cache_populate(void *ved, Object *ob)
       workbench_cache_texpaint_populate(wpd, ob);
     }
     else {
-      workbench_cache_common_populate(wpd, ob, color_type);
+      workbench_cache_common_populate(wpd, ob, color_type, &has_transp_mat);
+    }
+
+    if (draw_shadow) {
+      workbench_shadow_cache_populate(vedata, ob, has_transp_mat);
     }
   }
 }
@@ -372,10 +396,13 @@ static void workbench_draw_scene(void *ved)
 
   {
     GPU_framebuffer_bind(fbl->opaque_fb);
+    GPU_framebuffer_clear_stencil(fbl->opaque_fb, 0x00);
     DRW_draw_pass(psl->opaque_pass);
 
-    /* TODO(fclem) shadows */
-    // DRW_draw_pass(psl->shadow_pass);
+    if (psl->shadow_pass[0]) {
+      DRW_draw_pass(psl->shadow_pass[0]);
+      DRW_draw_pass(psl->shadow_pass[1]);
+    }
 
     {
       GPU_framebuffer_bind(fbl->opaque_infront_fb);
@@ -388,9 +415,6 @@ static void workbench_draw_scene(void *ved)
     GPU_framebuffer_bind(dfbl->default_fb);
     DRW_draw_pass(psl->composite_pass);
 
-    /* TODO(fclem) shadows : render shadowed areas */
-    // DRW_draw_pass(psl->composite_shadow_pass);
-
     /* TODO(fclem) ambient occlusion */
     // GPU_framebuffer_bind(dfbl->color_only_fb);
     // DRW_draw_pass(psl->ambient_occlusion_pass);
@@ -433,6 +457,18 @@ static void workbench_view_update(void *UNUSED(ved))
 {
 }
 
+static void workbench_id_update(void *UNUSED(vedata), struct ID *id)
+{
+  if (GS(id->name) == ID_OB) {
+    WORKBENCH_ObjectData *oed = (WORKBENCH_ObjectData *)DRW_drawdata_get(
+        id, &draw_engine_workbench_solid);
+    if (oed != NULL && oed->dd.recalc != 0) {
+      oed->shadow_bbox_dirty = (oed->dd.recalc & ID_RECALC_ALL) != 0;
+      oed->dd.recalc = 0;
+    }
+  }
+}
+
 static const DrawEngineDataSize workbench_data_size = DRW_VIEWPORT_DATA_SIZE(WORKBENCH_Data);
 
 DrawEngineType draw_engine_workbench = {
@@ -447,7 +483,7 @@ DrawEngineType draw_engine_workbench = {
     &workbench_cache_finish,
     &workbench_draw_scene,
     &workbench_view_update,
-    NULL,
+    &workbench_id_update,
     NULL,
 };
 
diff --git a/source/blender/draw/engines/workbench/workbench_materials.c b/source/blender/draw/engines/workbench/workbench_materials.c
index 2aeaee646e9..60349cd567b 100644
--- a/source/blender/draw/engines/workbench/workbench_materials.c
+++ b/source/blender/draw/engines/workbench/workbench_materials.c
@@ -466,8 +466,8 @@ static bool workbench_material_chunk_select(WORKBENCH_PrivateData *wpd, uint32_t
   return resource_changed;
 }
 
-DRWShadingGroup *workbench_material_setup(
-    WORKBENCH_PrivateData *wpd, Object *ob, int mat_nr, int color_type, bool hair)
+DRWShadingGroup *workbench_material_setup_ex(
+    WORKBENCH_PrivateData *wpd, Object *ob, int mat_nr, int color_type, bool hair, bool *r_transp)
 {
   Image *ima = NULL;
   ImageUser *iuser = NULL;
@@ -484,7 +484,7 @@ DRWShadingGroup *workbench_material_setup(
 
   switch (color_type) {
     case V3D_SHADING_TEXTURE_COLOR: {
-      return workbench_image_setup(wpd, ob, mat_nr, ima, iuser, interp, hair);
+      return workbench_image_setup_ex(wpd, ob, mat_nr, ima, iuser, interp, hair);
     }
     case V3D_SHADING_MATERIAL_COLOR: {
       /* For now, we use the same ubo for material and object coloring but with different indices.
@@ -497,6 +497,10 @@ DRWShadingGroup *workbench_material_setup(
       const bool transp = wpd->shading.xray_alpha < 1.0f || ma->a < 1.0f;
       WORKBENCH_Prepass *prepass = &wpd->prepass[transp][infront][hair];
 
+      if (r_transp && transp) {
+        *r_transp = true;
+      }
+
       DRWShadingGroup **grp_mat = NULL;
       /* A hashmap stores material shgroups to pack all similar drawcalls together. */
       if (BLI_ghash_ensure_p(prepass->material_hash, ma, (void ***)&grp_mat)) {
@@ -536,19 +540,22 @@ DRWShadingGroup *workbench_material_setup(
         grp = DRW_shgroup_create_sub(grp);
         DRW_shgroup_uniform_block(grp, "material_block", wpd->material_ubo_curr);
       }
+      if (r_transp && transp) {
+        *r_transp = true;
+      }
       return grp;
     }
   }
 }
 
 /* If ima is null, search appropriate image node but will fallback to purple texture otherwise. */
-DRWShadingGroup *workbench_image_setup(WORKBENCH_PrivateData *wpd,
-                                       Object *ob,
-                                       int mat_nr,
-                                       Image *ima,
-                                       ImageUser *iuser,
-                                       int interp,
-                                       bool hair)
+DRWShadingGroup *workbench_image_setup_ex(WORKBENCH_PrivateData *wpd,
+                                          Object *ob,
+                                          int mat_nr,
+                                          Image *ima,
+                                          ImageUser *iuser,
+                                          int interp,
+                                          bool hair)
 {
   GPUTexture *tex = NULL, *tex_tile_data = NULL;
 
diff --git a/source/blender/draw/engines/workbench/workbench_opaque.c b/source/blender/draw/engines/workbench/workbench_opaque.c
index d9c4c5a80a9..b968f257007 100644
--- a/source/blender/draw/engines/workbench/workbench_opaque.c
+++ b/source/blender/draw/engines/workbench/workbench_opaque.c
@@ -114,17 +114,18 @@ void workbench_opaque_cache_init(WORKBENCH_Data *data)
     }
   }
   {
-    DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_GREATER;
+    DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_GREATER | DRW_STATE_STENCIL_EQUAL;
 
     DRW_PASS_CREATE(psl->composite_pass, state);
 
     sh = workbench_shader_composite_get(wpd);
 
     grp = DRW_shgroup_create(sh, psl->composite_pass);
+    DRW_shgroup_uniform_block_persistent(grp, "world_block", wpd->world_ubo);
+    DRW_shgroup_uniform_texture_persistent(grp, "materialBuffer", wpd->material_buffer_tx);
+    DRW_shgroup_uniform_texture_persistent(grp, "normalBuffer", wpd->normal_buffer_tx);
+    DRW_shgroup_uniform_bool_copy(grp, "forceShadowing", false);
     DRW_shgroup_stencil_mask(grp, 0x00);
-    DRW_shgroup_uniform_block(grp, "world_block", wpd->world_ubo);
-    DRW_shgroup_uniform_texture(grp, "materialBuffer", wpd->material_buffer_tx);
-    DRW_shgroup_uniform_texture(grp, "normalBuffer", wpd->normal_buffer_tx);
 
     const bool use_spec = workbench_is_specular_highlight_enabled(wpd);
 
@@ -134,14 +135,24 @@ void workbench_opaque_cache_init(WORKBENCH_Data *data)
                                       STUDIOLIGHT_MATCAP_SPECULAR_GPUTEXTURE);
       struct GPUTexture *diff_tx = wpd->studio_light->matcap_diffuse.gputexture;
       struct GPUTexture *spec_tx = wpd->studio_light->matcap_specular.gputexture;
-      DRW_shgroup_uniform_texture(grp, "matcapDiffuseImage", diff_tx);
-      DRW_shgroup_uniform_texture(grp, "matcapSpecularImage", use_spec ? spec_tx : diff_tx);
+      spec_tx = use_spec ? spec_tx : diff_tx;
+      DRW_shgroup_uniform_texture_persistent(grp, "matcapDiffuseImage", diff_tx);
+      DRW_shgroup_uniform_texture_persistent(grp, "matcapSpecularImage", spec_tx);
       DRW_shgroup_uniform_bool_copy(grp, "useSpecularMatcap", use_spec);
     }
     else if (STUDIOLIGHT_TYPE_STUDIO_ENABLED(wpd)) {
       DRW_shgroup_uniform_bool_copy(grp, "useSpecularLighting", use_spec);
     }
     DRW_shgroup_call_procedural_triangles(grp, NULL, 1);
+
+    if (true) {
+      grp = DRW_shgroup_create_sub(grp);
+      DRW_shgroup_uniform_bool_copy(grp, "forceShadowing", true);
+      DRW_shgroup_state_disable(grp, DRW_STATE_STENCIL_EQUAL);
+      DRW_shgroup_state_enable(grp, DRW_STATE_STENCIL_NEQUAL);
+      DRW_shgroup_stencil_mask(grp, 0x00);
+      DRW_shgroup_call_procedural_triangles(grp, NULL, 1);
+    }
   }
   {
     DRWState state = DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_ALWAYS | DRW_STATE_WRITE_STENCIL |
@@ -152,8 +163,8 @@ void workbench_opaque_cache_init(WORKBENCH_Data *data)
     sh = workbench_shader_merge_infront_get(wpd);
 
     grp = DRW_shgroup_create(sh, psl->merge_infront_pass);
-    DRW_shgroup_stencil_mask(grp, 0x00);
     DRW_shgroup_uniform_texture_ref(grp, "depthBuffer", &dtxl->depth_in_front);
+    DRW_shgroup_stencil_mask(grp, 0x00);
     DRW_shgroup_call_procedural_triangles(grp, NULL, 1);
   }
 }
diff --git a/source/blender/draw/engines/workbench/workbench_private.h b/source/blender/draw/engines/workbench/workbench_private.h
index 90c1908100f..155deba8380 100644
--- a/source/blender/draw/engines/workbench/workbench_private.h
+++ b/source/blender/draw/engines/workbench/workbench_private.h
@@ -34,6 +34,8 @@
 
 #include "workbench_engine.h"
 
+extern struct DrawEngineType draw_engine_workbench;
+
 #define WORKBENCH_ENGINE "BLENDER_WORKBENCH"
 /* TODO put them in workbench_shader.c */
 #define MAX_COMPOSITE_SHADERS 3
@@ -42,6 +44,8 @@
 #define MAX_CAVITY_SHADERS (1 << 3)
 #define MAX_MATERIAL (1 << 12)
 
+#define DEBUG_SHADOW_VOLUME 0
+
 #define TEXTURE_DRAWING_ENABLED(wpd) (wpd->shading.color_type == V3D_SHADING_TEXTURE_COLOR)
 #define VERTEX_COLORS_ENABLED(wpd) (wpd->shading.color_type == V3D_SHADING_VERTEX_COLOR)
 #define MATERIAL_COLORS_ENABLED(wpd) (wpd->shading.color_type == V3D_SHADING_MATERIAL_COLOR)
@@ -143,6 +147,7 @@ typedef struct WORKBENCH_PassList {
   /* deferred rendering */
   struct DRWPass *opaque_pass;
   struct DRWPass *opaque_infront_pass;
+  struct DRWPass *shadow_pass[2];
   struct DRWPass *merge_infront_pass;
   struct DRWPass *prepass_pass;
   struct DRWPass *prepass_hair_pass;
@@ -207,6 +212,7 @@ typedef struct WORKBENCH_UBO_World {
   float viewport_size[2], viewport_size_inv[2];
   float object_outline_color[4];
   float shadow_direction_vs[4];
+  float shadow_focus, shadow_shift, shadow_mul, shadow_add;
   WORKBENCH_UBO_Light lights[4];
   float ambient_color[4];
   int matcap_orientation;
@@ -299,6 +305,12 @@ typedef struct WORKBENCH_PrivateData {
   int material_chunk_curr;
   int material_index;
 
+  /* Shadow */
+  struct DRWShadingGroup *shadow_pass_grp[2];
+  struct DRWShadingGroup *shadow_fail_grp[2];
+  struct DRWShadingGroup *shadow_fail_caps_grp[2];
+  float light_direction_ws[3];
+
   /* Volumes */
   bool volumes_do;
   ListBase smoke_domains;
@@ -493,6 +505,10 @@ void workbench_opaque_cache_init(WORKBENCH_Data *data);
 void workbench_transparent_engine_init(WORKBENCH_Data *data);
 void workbench_transparent_cache_init(WORKBENCH_Data *data);
 
+/* workbench_shadow.c */
+void workbench_shadow_cache_init(WORKBENCH_Data *data);
+void workbench_shadow_cache_populate(WORKBENCH_Data *data, Object *ob, const bool has_transp_mat);
+
 /* workbench_shader.c */
 GPUShader *workbench_shader_opaque_get(WORKBENCH_PrivateData *wpd, bool hair);
 GPUShader *workbench_shader_opaque_image_get(WORKBENCH_PrivateData *wpd, bool hair, bool tiled);
@@ -505,6 +521,9 @@ GPUShader *workbench_shader_transparent_image_get(WORKBENCH_PrivateData *wpd,
                                                   bool tiled);
 GPUShader *workbench_shader_transparent_resolve_get(WORKBENCH_PrivateData *wpd);
 
+GPUShader *workbench_shader_shadow_pass_get(bool manifold);
+GPUShader *workbench_shader_shadow_fail_get(bool manifold, bool cap);
+
 void workbench_shader_library_ensure(void);
 void workbench_shader_free(void);
 
@@ -609,21 +628,31 @@ void workbench_material_ubo_data(WORKBENCH_PrivateData *wpd,
                                  WORKBENCH_UBO_Material *data,
                                  int color_type);
 
-DRWShadingGroup *workbench_material_setup(
-    WORKBENCH_PrivateData *wpd, Object *ob, int mat_nr, int color_type, bool hair);
-DRWShadingGroup *workbench_image_setup(WORKBENCH_PrivateData *wpd,
-                                       Object *ob,
-                                       int mat_nr,
-                                       Image *ima,
-                                       ImageUser *iuser,
-                                       int interp,
-                                       bool hair);
+DRWShadingGroup *workbench_material_setup_ex(
+    WORKBENCH_PrivateData *wpd, Object *ob, int mat_nr, int color_type, bool hair, bool *r_transp);
+DRWShadingGroup *workbench_image_setup_ex(WORKBENCH_PrivateData *wpd,
+                                          Object *ob,
+                                          int mat_nr,
+                                          Image *ima,
+                                          ImageUser *iuser,
+                                          int interp,
+                                          bool hair);
+
+#define workbench_material_setup(wpd, ob, mat_nr, color_type, r_transp) \
+  workbench_material_setup_ex(wpd, ob, mat_nr, color_type, false, r_transp)
+#define workbench_image_setup(wpd, ob, mat_nr, ima, iuser, interp) \
+  workbench_image_setup_ex(wpd, ob, mat_nr, ima, iuser, interp, false)
+
+#define workbench_material_hair_setup(wpd, ob, mat_nr, color_type) \
+  workbench_material_setup_ex(wpd, ob, mat_nr, color_type, true, 0)
+#define workbench_image_hair_setup(wpd, ob, mat_nr, ima, iuser, interp) \
+  workbench_image_setup_ex(wpd, ob, mat_nr, ima, iuser, interp, true)
 
 /* workbench_studiolight.c */
 void studiolight_update_world(WORKBENCH_PrivateData *wpd,
                               StudioLight *sl,
                               WORKBENCH_UBO_World *wd);
-void studiolight_update_light(WORKBENCH_PrivateData *wpd, const float light_direction[3]);
+void studiolight_update_light(WORKBENCH_PrivateData *wpd);
 bool studiolight_object_cast_visible_shadow(WORKBENCH_PrivateData *wpd,
                                             Object *ob,
                                             WORKBENCH_ObjectData *oed);
diff --git a/source/blender/draw/engines/workbench/workbench_shader.c b/source/blender/draw/engines/workbench/workbench_shader.c
index bc769001f8c..3470d42608e 100644
--- a/source/blender/draw/engines/workbench/workbench_shader.c
+++ b/source/blender/draw/engines/workbench/workbench_shader.c
@@ -33,6 +33,7 @@ extern char datatoc_common_view_lib_glsl[];
 extern char datatoc_workbench_prepass_vert_glsl[];
 extern char datatoc_workbench_prepass_hair_vert_glsl[];
 extern char datatoc_workbench_prepass_frag_glsl[];
+
 // extern char datatoc_workbench_cavity_frag_glsl[];
 // extern char datatoc_workbench_forward_composite_frag_glsl[];
 // extern char datatoc_workbench_deferred_composite_frag_glsl[];
@@ -77,6 +78,9 @@ static struct {
   struct GPUShader *oit_resolve_sh;
   struct GPUShader *merge_infront_sh;
 
+  struct GPUShader *shadow_depth_pass_sh[2];
+  struct GPUShader *shadow_depth_fail_sh[2][2];
+
   struct DRWShaderLibrary *lib;
 } e_data = {{{{NULL}}}};
 
@@ -241,6 +245,44 @@ GPUShader *workbench_shader_transparent_resolve_get(WORKBENCH_PrivateData *wpd)
   return e_data.oit_resolve_sh;
 }
 
+static GPUShader *workbench_shader_shadow_pass_get_ex(bool depth_pass, bool manifold, bool cap)
+{
+  struct GPUShader **shader = (depth_pass) ? &e_data.shadow_depth_pass_sh[manifold] :
+                                             &e_data.shadow_depth_fail_sh[manifold][cap];
+
+  if (*shader == NULL) {
+#if DEBUG_SHADOW_VOLUME
+    const char *shadow_frag = datatoc_workbench_shadow_debug_frag_glsl;
+#else
+    const char *shadow_frag = datatoc_gpu_shader_depth_only_frag_glsl;
+#endif
+
+    *shader = GPU_shader_create_from_arrays({
+        .vert = (const char *[]){datatoc_common_view_lib_glsl,
+                                 datatoc_workbench_shadow_vert_glsl,
+                                 NULL},
+        .geom = (const char *[]){(cap) ? datatoc_workbench_shadow_caps_geom_glsl :
+                                         datatoc_workbench_shadow_geom_glsl,
+                                 NULL},
+        .frag = (const char *[]){shadow_frag, NULL},
+        .defs = (const char *[]){(depth_pass) ? "#define SHADOW_PASS\n" : "#define SHADOW_FAIL\n",
+                                 (manifold) ? "" : "#define DOUBLE_MANIFOLD\n",
+                                 NULL},
+    });
+  }
+  return *shader;
+}
+
+GPUShader *workbench_shader_shadow_pass_get(bool manifold)
+{
+  return workbench_shader_shadow_pass_get_ex(true, manifold, false);
+}
+
+GPUShader *workbench_shader_shadow_fail_get(bool manifold, bool cap)
+{
+  return workbench_shader_shadow_pass_get_ex(false, manifold, cap);
+}
+
 void workbench_shader_free(void)
 {
   for (int j = 0; j < sizeof(e_data.opaque_prepass_sh_cache) / sizeof(void *); j++) {
@@ -255,6 +297,14 @@ void workbench_shader_free(void)
     struct GPUShader **sh_array = &e_data.opaque_composite_sh[0];
     DRW_SHADER_FREE_SAFE(sh_array[j]);
   }
+  for (int j = 0; j < sizeof(e_data.shadow_depth_pass_sh) / sizeof(void *); j++) {
+    struct GPUShader **sh_array = &e_data.shadow_depth_pass_sh[0];
+    DRW_SHADER_FREE_SAFE(sh_array[j]);
+  }
+  for (int j = 0; j < sizeof(e_data.shadow_depth_fail_sh) / sizeof(void *); j++) {
+    struct GPUShader **sh_array = &e_data.shadow_depth_fail_sh[0][0];
+    DRW_SHADER_FREE_SAFE(sh_array[j]);
+  }
   DRW_SHADER_FREE_SAFE(e_data.oit_resolve_sh);
   DRW_SHADER_FREE_SAFE(e_data.merge_infront_sh);
 
diff --git a/source/blender/draw/engines/workbench/workbench_shadow.c b/source/blender/draw/engines/workbench/workbench_shadow.c
index 5be863e387d..635206cd38f 100644
--- a/source/blender/draw/engines/workbench/workbench_shadow.c
+++ b/source/blender/draw/engines/workbench/workbench_shadow.c
@@ -22,4 +22,116 @@
 
 #include "DRW_render.h"
 
-#include "workbench_engine.h"
\ No newline at end of file
+#include "workbench_engine.h"
+#include "workbench_private.h"
+
+void workbench_shadow_cache_init(WORKBENCH_Data *data)
+{
+  WORKBENCH_PassList *psl = data->psl;
+  WORKBENCH_PrivateData *wpd = data->stl->wpd;
+  struct GPUShader *sh;
+  DRWShadingGroup *grp;
+
+  studiolight_update_light(wpd);
+
+  if (SHADOW_ENABLED(wpd)) {
+#if DEBUG_SHADOW_VOLUME
+    DRWState depth_pass_state = DRW_STATE_DEPTH_LESS;
+    DRWState depth_fail_state = DRW_STATE_DEPTH_GREATER_EQUAL;
+    DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_ADD_FULL;
+#else
+    DRWState depth_pass_state = DRW_STATE_WRITE_STENCIL_SHADOW_PASS;
+    DRWState depth_fail_state = DRW_STATE_WRITE_STENCIL_SHADOW_FAIL;
+    DRWState state = DRW_STATE_DEPTH_LESS | DRW_STATE_STENCIL_ALWAYS;
+#endif
+
+    /* TODO(fclem) Merge into one pass with subpasses. */
+    DRW_PASS_CREATE(psl->shadow_pass[0], state | depth_pass_state);
+    DRW_PASS_CREATE(psl->shadow_pass[1], state | depth_fail_state);
+
+    /* Stencil Shadow passes. */
+    for (int manifold = 0; manifold < 2; manifold++) {
+      sh = workbench_shader_shadow_pass_get(manifold);
+      wpd->shadow_pass_grp[manifold] = grp = DRW_shgroup_create(sh, psl->shadow_pass[0]);
+      DRW_shgroup_stencil_mask(grp, 0xFF); /* Needed once to set the stencil state for the pass. */
+
+      sh = workbench_shader_shadow_fail_get(manifold, false);
+      wpd->shadow_fail_grp[manifold] = grp = DRW_shgroup_create(sh, psl->shadow_pass[1]);
+      DRW_shgroup_stencil_mask(grp, 0xFF); /* Needed once to set the stencil state for the pass. */
+
+      sh = workbench_shader_shadow_fail_get(manifold, true);
+      wpd->shadow_fail_caps_grp[manifold] = grp = DRW_shgroup_create(sh, psl->shadow_pass[1]);
+    }
+  }
+  else {
+    psl->shadow_pass[0] = NULL;
+    psl->shadow_pass[1] = NULL;
+  }
+}
+
+static void workbench_init_object_data(DrawData *dd)
+{
+  WORKBENCH_ObjectData *data = (WORKBENCH_ObjectData *)dd;
+  data->shadow_bbox_dirty = true;
+}
+
+void workbench_shadow_cache_populate(WORKBENCH_Data *data, Object *ob, const bool has_transp_mat)
+{
+  WORKBENCH_PrivateData *wpd = data->stl->wpd;
+
+  bool is_manifold;
+  struct GPUBatch *geom_shadow = DRW_cache_object_edge_detection_get(ob, &is_manifold);
+  if (geom_shadow == NULL) {
+    return;
+  }
+
+  WORKBENCH_ObjectData *engine_object_data = (WORKBENCH_ObjectData *)DRW_drawdata_ensure(
+      &ob->id,
+      &draw_engine_workbench,
+      sizeof(WORKBENCH_ObjectData),
+      &workbench_init_object_data,
+      NULL);
+
+  if (studiolight_object_cast_visible_shadow(wpd, ob, engine_object_data)) {
+    mul_v3_mat3_m4v3(engine_object_data->shadow_dir, ob->imat, wpd->light_direction_ws);
+
+    DRWShadingGroup *grp;
+    bool use_shadow_pass_technique = !studiolight_camera_in_object_shadow(
+        wpd, ob, engine_object_data);
+
+    /* Shadow pass technique needs object to be have all its surface opaque. */
+    if (has_transp_mat) {
+      use_shadow_pass_technique = false;
+    }
+
+    if (use_shadow_pass_technique) {
+      grp = DRW_shgroup_create_sub(wpd->shadow_pass_grp[is_manifold]);
+      DRW_shgroup_uniform_vec3(grp, "lightDirection", engine_object_data->shadow_dir, 1);
+      DRW_shgroup_uniform_float_copy(grp, "lightDistance", 1e5f);
+      DRW_shgroup_call_no_cull(grp, geom_shadow, ob);
+#if DEBUG_SHADOW_VOLUME
+      DRW_debug_bbox(&engine_object_data->shadow_bbox, (float[4]){1.0f, 0.0f, 0.0f, 1.0f});
+#endif
+    }
+    else {
+      float extrude_distance = studiolight_object_shadow_distance(wpd, ob, engine_object_data);
+
+      /* TODO(fclem): only use caps if they are in the view frustum. */
+      const bool need_caps = true;
+      if (need_caps) {
+        grp = DRW_shgroup_create_sub(wpd->shadow_fail_caps_grp[is_manifold]);
+        DRW_shgroup_uniform_vec3(grp, "lightDirection", engine_object_data->shadow_dir, 1);
+        DRW_shgroup_uniform_float_copy(grp, "lightDistance", extrude_distance);
+        DRW_shgroup_call_no_cull(grp, DRW_cache_object_surface_get(ob), ob);
+      }
+
+      grp = DRW_shgroup_create_sub(wpd->shadow_fail_grp[is_manifold]);
+      DRW_shgroup_uniform_vec3(grp, "lightDirection", engine_object_data->shadow_dir, 1);
+      DRW_shgroup_uniform_float_copy(grp, "lightDistance", extrude_distance);
+      DRW_shgroup_call_no_cull(grp, geom_shadow, ob);
+#if DEBUG_SHADOW_VOLUME
+      DRW_debug_bbox(&engine_object_data->shadow_bbox, (float[4]){0.0f, 1.0f, 0.0f, 1.0f});
+#endif
+    }
+  }
+}
\ No newline at end of file
diff --git a/source/blender/draw/engines/workbench/workbench_studiolight.c b/source/blender/draw/engines/workbench/workbench_studiolight.c
index 4eee0ce3cce..e9dd6c63feb 100644
--- a/source/blender/draw/engines/workbench/workbench_studiolight.c
+++ b/source/blender/draw/engines/workbench/workbench_studiolight.c
@@ -94,23 +94,24 @@ static void compute_parallel_lines_nor_and_dist(const float v1[2],
   }
 }
 
-void studiolight_update_light(WORKBENCH_PrivateData *wpd, const float light_direction[3])
+void studiolight_update_light(WORKBENCH_PrivateData *wpd)
 {
-  wpd->shadow_changed = !compare_v3v3(wpd->cached_shadow_direction, light_direction, 1e-5f);
+  wpd->shadow_changed = !compare_v3v3(
+      wpd->cached_shadow_direction, wpd->light_direction_ws, 1e-5f);
 
   if (wpd->shadow_changed) {
     float up[3] = {0.0f, 0.0f, 1.0f};
     unit_m4(wpd->shadow_mat);
 
     /* TODO fix singularity. */
-    copy_v3_v3(wpd->shadow_mat[2], light_direction);
+    copy_v3_v3(wpd->shadow_mat[2], wpd->light_direction_ws);
     cross_v3_v3v3(wpd->shadow_mat[0], wpd->shadow_mat[2], up);
     normalize_v3(wpd->shadow_mat[0]);
     cross_v3_v3v3(wpd->shadow_mat[1], wpd->shadow_mat[2], wpd->shadow_mat[0]);
 
     invert_m4_m4(wpd->shadow_inv, wpd->shadow_mat);
 
-    copy_v3_v3(wpd->cached_shadow_direction, light_direction);
+    copy_v3_v3(wpd->cached_shadow_direction, wpd->light_direction_ws);
   }
 
   float planes[6][4];
diff --git a/source/blender/draw/engines/workbench/workbench_transparent.c b/source/blender/draw/engines/workbench/workbench_transparent.c
index 297d07c03c6..2efa08683c3 100644
--- a/source/blender/draw/engines/workbench/workbench_transparent.c
+++ b/source/blender/draw/engines/workbench/workbench_transparent.c
@@ -56,6 +56,7 @@ static void workbench_transparent_lighting_uniforms(WORKBENCH_PrivateData *wpd,
 {
   const bool use_spec = workbench_is_specular_highlight_enabled(wpd);
   DRW_shgroup_uniform_block_persistent(grp, "world_block", wpd->world_ubo);
+  DRW_shgroup_uniform_bool_copy(grp, "forceShadowing", false);
 
   if (STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)) {
     BKE_studiolight_ensure_flag(wpd->studio_light,
diff --git a/source/blender/draw/intern/draw_hair.c b/source/blender/draw/intern/draw_hair.c
index fa03c28b470..7b0fa3ce1ec 100644
--- a/source/blender/draw/intern/draw_hair.c
+++ b/source/blender/draw/intern/draw_hair.c
@@ -128,7 +128,7 @@ static DRWShadingGroup *drw_shgroup_create_hair_procedural_ex(Object *object,
       object, psys, md, &hair_cache, subdiv, thickness_res);
 
   DRWShadingGroup *shgrp;
-  if (shgrp) {
+  if (shgrp_parent) {
     shgrp = DRW_shgroup_create_sub(shgrp_parent);
   }
   else if (gpu_mat) {