TexturePaint: Force Workbench Texture Color Mode

When in texture paint mode and in solid mode the object that is being
texture painted will be rendered by the workbench engine with textures.
All other objects would render the same. For other cases the texture paint
draw engine will still draw the texture.

The texture mode draw engine now only drawn the masks. The opacity
sliders influences the texture mask.

This change has been implemented conserably. In the future we need to
look into making this better, like adding support that every object
can be colored differently. Currently when rendering in the workbench
we can have up to 3 different color types active (what the user selected,
the fallback in case no materials have been configured and this one,
forcing textures)

Reviewed By: fclem, brecht

Differential Revision: https://developer.blender.org/D5190

4 files changed, 240 insertions, 67 deletions

diff --git a/source/blender/draw/engines/workbench/workbench_deferred.c b/source/blender/draw/engines/workbench/workbench_deferred.c
index 31549c6f752..8c9dc43afa8 100644
--- a/source/blender/draw/engines/workbench/workbench_deferred.c
+++ b/source/blender/draw/engines/workbench/workbench_deferred.c
@@ -215,13 +215,16 @@ static GPUShader *workbench_cavity_shader_get(bool cavity, bool curvature)
 static GPUShader *ensure_deferred_prepass_shader(WORKBENCH_PrivateData *wpd,
                                                  bool is_uniform_color,
                                                  bool is_hair,
+                                                 bool is_texture_painting,
                                                  eGPUShaderConfig sh_cfg)
 {
   WORKBENCH_DEFERRED_Shaders *sh_data = &e_data.sh_data[sh_cfg];
-  int index = workbench_material_get_prepass_shader_index(wpd, is_uniform_color, is_hair);
+  int index = workbench_material_get_prepass_shader_index(
+      wpd, is_uniform_color, is_hair, is_texture_painting);
   if (sh_data->prepass_sh_cache[index] == NULL) {
     const GPUShaderConfigData *sh_cfg_data = &GPU_shader_cfg_data[sh_cfg];
-    char *defines = workbench_material_build_defines(wpd, is_uniform_color, is_hair);
+    char *defines = workbench_material_build_defines(
+        wpd, is_uniform_color, is_hair, is_texture_painting);
     char *prepass_vert = workbench_build_prepass_vert(is_hair);
     char *prepass_frag = workbench_build_prepass_frag();
     sh_data->prepass_sh_cache[index] = GPU_shader_create_from_arrays({
@@ -240,7 +243,7 @@ static GPUShader *ensure_deferred_composite_shader(WORKBENCH_PrivateData *wpd)
 {
   int index = workbench_material_get_composite_shader_index(wpd);
   if (e_data.composite_sh_cache[index] == NULL) {
-    char *defines = workbench_material_build_defines(wpd, false, false);
+    char *defines = workbench_material_build_defines(wpd, false, false, false);
     char *composite_frag = workbench_build_composite_frag(wpd);
     e_data.composite_sh_cache[index] = DRW_shader_create_fullscreen(composite_frag, defines);
     MEM_freeN(composite_frag);
@@ -267,10 +270,11 @@ static GPUShader *ensure_background_shader(WORKBENCH_PrivateData *wpd)
 
 static void select_deferred_shaders(WORKBENCH_PrivateData *wpd, eGPUShaderConfig sh_cfg)
 {
-  wpd->prepass_sh = ensure_deferred_prepass_shader(wpd, false, false, sh_cfg);
-  wpd->prepass_hair_sh = ensure_deferred_prepass_shader(wpd, false, true, sh_cfg);
-  wpd->prepass_uniform_sh = ensure_deferred_prepass_shader(wpd, true, false, sh_cfg);
-  wpd->prepass_uniform_hair_sh = ensure_deferred_prepass_shader(wpd, true, true, sh_cfg);
+  wpd->prepass_sh = ensure_deferred_prepass_shader(wpd, false, false, false, sh_cfg);
+  wpd->prepass_hair_sh = ensure_deferred_prepass_shader(wpd, false, true, false, sh_cfg);
+  wpd->prepass_uniform_sh = ensure_deferred_prepass_shader(wpd, true, false, false, sh_cfg);
+  wpd->prepass_uniform_hair_sh = ensure_deferred_prepass_shader(wpd, true, true, false, sh_cfg);
+  wpd->prepass_textured_sh = ensure_deferred_prepass_shader(wpd, false, false, true, sh_cfg);
   wpd->composite_sh = ensure_deferred_composite_shader(wpd);
   wpd->background_sh = ensure_background_shader(wpd);
 }
@@ -483,7 +487,7 @@ void workbench_deferred_engine_init(WORKBENCH_Data *vedata)
     e_data.composite_buffer_tx = DRW_texture_pool_query_2d(
         size[0], size[1], comp_tex_format, &draw_engine_workbench_solid);
 
-    if (MATDATA_PASS_ENABLED(wpd) || GPU_unused_fb_slot_workaround()) {
+    if (workbench_is_matdata_pass_enabled(wpd) || GPU_unused_fb_slot_workaround()) {
       e_data.color_buffer_tx = DRW_texture_pool_query_2d(
           size[0], size[1], col_tex_format, &draw_engine_workbench_solid);
     }
@@ -523,7 +527,7 @@ void workbench_deferred_engine_init(WORKBENCH_Data *vedata)
                                       GPU_ATTACHMENT_TEXTURE(e_data.composite_buffer_tx),
                                   });
 
-    if (!MATDATA_PASS_ENABLED(wpd) && !GPU_unused_fb_slot_workaround()) {
+    if (!workbench_is_matdata_pass_enabled(wpd) && !GPU_unused_fb_slot_workaround()) {
       e_data.color_buffer_tx = DRW_texture_pool_query_2d(
           size[0], size[1], col_tex_format, &draw_engine_workbench_solid);
     }
@@ -675,7 +679,7 @@ void workbench_deferred_engine_free(void)
 static void workbench_composite_uniforms(WORKBENCH_PrivateData *wpd, DRWShadingGroup *grp)
 {
   DRW_shgroup_uniform_block(grp, "world_block", wpd->world_ubo);
-  if (MATDATA_PASS_ENABLED(wpd)) {
+  if (workbench_is_matdata_pass_enabled(wpd)) {
     DRW_shgroup_uniform_texture_ref(grp, "materialBuffer", &e_data.color_buffer_tx);
   }
   else {
@@ -714,7 +718,6 @@ void workbench_deferred_cache_init(WORKBENCH_Data *vedata)
   Scene *scene = draw_ctx->scene;
 
   workbench_volume_cache_init(vedata);
-
   select_deferred_shaders(wpd, draw_ctx->sh_cfg);
 
   /* Background Pass */
@@ -869,7 +872,7 @@ static WORKBENCH_MaterialData *get_or_create_material_data(WORKBENCH_Data *vedat
   const bool is_ghost = (ob->dtx & OB_DRAWXRAY);
 
   /* Solid */
-  workbench_material_update_data(wpd, ob, mat, &material_template);
+  workbench_material_update_data(wpd, ob, mat, &material_template, color_type);
   material_template.object_id = OBJECT_ID_PASS_ENABLED(wpd) ? engine_object_data->object_id : 1;
   material_template.color_type = color_type;
   material_template.ima = ima;
@@ -880,9 +883,14 @@ static WORKBENCH_MaterialData *get_or_create_material_data(WORKBENCH_Data *vedat
   material = BLI_ghash_lookup(wpd->material_hash, POINTER_FROM_UINT(hash));
   if (material == NULL) {
     material = MEM_mallocN(sizeof(WORKBENCH_MaterialData), __func__);
+    /* select the correct prepass shader */
+    GPUShader *shader = (wpd->shading.color_type == color_type) ? wpd->prepass_sh :
+                                                                  wpd->prepass_uniform_sh;
+    if (color_type == V3D_SHADING_TEXTURE_COLOR) {
+      shader = wpd->prepass_textured_sh;
+    }
     material->shgrp = DRW_shgroup_create(
-        (wpd->shading.color_type == color_type) ? wpd->prepass_sh : wpd->prepass_uniform_sh,
-        (ob->dtx & OB_DRAWXRAY) ? psl->ghost_prepass_pass : psl->prepass_pass);
+        shader, (ob->dtx & OB_DRAWXRAY) ? psl->ghost_prepass_pass : psl->prepass_pass);
     workbench_material_copy(material, &material_template);
     DRW_shgroup_stencil_mask(material->shgrp, (ob->dtx & OB_DRAWXRAY) ? 0x00 : 0xFF);
     DRW_shgroup_uniform_int(material->shgrp, "object_id", &material->object_id, 1);
@@ -935,6 +943,49 @@ static void workbench_cache_populate_particles(WORKBENCH_Data *vedata, Object *o
   }
 }
 
+static void workbench_cache_populate_texture_paint_mode(WORKBENCH_Data *vedata, Object *ob)
+{
+  WORKBENCH_StorageList *stl = vedata->stl;
+  WORKBENCH_PrivateData *wpd = stl->g_data;
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+
+  Scene *scene = draw_ctx->scene;
+  const bool use_sculpt_pbvh = BKE_sculptsession_use_pbvh_draw(ob, draw_ctx->v3d);
+  WORKBENCH_MaterialData *material;
+
+  /* Force workbench to render active object textured when in texture paint mode */
+  const ImagePaintSettings *imapaint = &scene->toolsettings->imapaint;
+
+  /* Single Image mode */
+  if (imapaint->mode == IMAGEPAINT_MODE_IMAGE) {
+    Image *image = imapaint->canvas;
+    int interp = (imapaint->interp == IMAGEPAINT_INTERP_LINEAR) ? SHD_INTERP_LINEAR :
+                                                                  SHD_INTERP_CLOSEST;
+    int color_type = workbench_material_determine_color_type(wpd, image, ob, use_sculpt_pbvh);
+    struct GPUBatch *geom = DRW_cache_mesh_surface_texpaint_single_get(ob);
+    material = get_or_create_material_data(vedata, ob, NULL, image, NULL, color_type, interp);
+
+    DRW_shgroup_call(material->shgrp, geom, ob);
+  }
+  else {
+    /* IMAGEPAINT_MODE_MATERIAL */
+    const int materials_len = MAX2(1, ob->totcol);
+    struct GPUBatch **geom_array = DRW_cache_mesh_surface_texpaint_get(ob);
+    for (int i = 0; i < materials_len; i++) {
+      if (geom_array != NULL && geom_array[i] != NULL) {
+        Material *mat;
+        Image *image;
+        ImageUser *iuser;
+        int interp;
+        workbench_material_get_image_and_mat(ob, i + 1, &image, &iuser, &interp, &mat);
+        int color_type = workbench_material_determine_color_type(wpd, image, ob, use_sculpt_pbvh);
+        material = get_or_create_material_data(vedata, ob, mat, image, iuser, color_type, interp);
+        DRW_shgroup_call(material->shgrp, geom_array[i], ob);
+      }
+    }
+  }
+}
+
 void workbench_deferred_solid_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 {
   WORKBENCH_StorageList *stl = vedata->stl;
@@ -975,8 +1026,13 @@ void workbench_deferred_solid_cache_populate(WORKBENCH_Data *vedata, Object *ob)
     const int materials_len = MAX2(1, ob->totcol);
     const Mesh *me = (ob->type == OB_MESH) ? ob->data : NULL;
     bool has_transp_mat = false;
+    const bool use_texture_paint_drawing = workbench_is_object_in_texture_paint_mode(ob) && me &&
+                                           me->mloopuv;
 
-    if (!use_sculpt_pbvh && TEXTURE_DRAWING_ENABLED(wpd) && me && me->mloopuv) {
+    if (use_texture_paint_drawing) {
+      workbench_cache_populate_texture_paint_mode(vedata, ob);
+    }
+    else if (!use_sculpt_pbvh && TEXTURE_DRAWING_ENABLED(wpd) && me && me->mloopuv) {
       /* Draw textured */
       struct GPUBatch **geom_array = DRW_cache_mesh_surface_texpaint_get(ob);
       for (int i = 0; i < materials_len; i++) {
@@ -990,7 +1046,7 @@ void workbench_deferred_solid_cache_populate(WORKBENCH_Data *vedata, Object *ob)
               wpd, image, ob, use_sculpt_pbvh);
           if (color_type == V3D_SHADING_MATERIAL_COLOR && mat && mat->a < 1.0) {
             material = workbench_forward_get_or_create_material_data(
-                vedata, ob, mat, image, iuser, color_type, 0, use_sculpt_pbvh);
+                vedata, ob, mat, image, iuser, color_type, 0);
             has_transp_mat = true;
           }
           else {
@@ -1010,7 +1066,7 @@ void workbench_deferred_solid_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 
       if ((ob->color[3] < 1.0f) && (color_type == V3D_SHADING_OBJECT_COLOR)) {
         material = workbench_forward_get_or_create_material_data(
-            vedata, ob, NULL, NULL, NULL, color_type, 0, use_sculpt_pbvh);
+            vedata, ob, NULL, NULL, NULL, color_type, 0);
         has_transp_mat = true;
       }
       else {
@@ -1045,7 +1101,7 @@ void workbench_deferred_solid_cache_populate(WORKBENCH_Data *vedata, Object *ob)
           struct Material *mat = give_current_material(ob, i + 1);
           if (mat != NULL && mat->a < 1.0f) {
             material = workbench_forward_get_or_create_material_data(
-                vedata, ob, mat, NULL, NULL, V3D_SHADING_MATERIAL_COLOR, 0, use_sculpt_pbvh);
+                vedata, ob, mat, NULL, NULL, V3D_SHADING_MATERIAL_COLOR, 0);
             has_transp_mat = true;
           }
           else {
@@ -1068,7 +1124,7 @@ void workbench_deferred_solid_cache_populate(WORKBENCH_Data *vedata, Object *ob)
             Material *mat = give_current_material(ob, i + 1);
             if (mat != NULL && mat->a < 1.0f) {
               material = workbench_forward_get_or_create_material_data(
-                  vedata, ob, mat, NULL, NULL, V3D_SHADING_MATERIAL_COLOR, 0, use_sculpt_pbvh);
+                  vedata, ob, mat, NULL, NULL, V3D_SHADING_MATERIAL_COLOR, 0);
               has_transp_mat = true;
             }
             else {
diff --git a/source/blender/draw/engines/workbench/workbench_forward.c b/source/blender/draw/engines/workbench/workbench_forward.c
index 9245d13eab0..5e8cbf71c1e 100644
--- a/source/blender/draw/engines/workbench/workbench_forward.c
+++ b/source/blender/draw/engines/workbench/workbench_forward.c
@@ -141,8 +141,7 @@ WORKBENCH_MaterialData *workbench_forward_get_or_create_material_data(WORKBENCH_
                                                                       Image *ima,
                                                                       ImageUser *iuser,
                                                                       int color_type,
-                                                                      int interp,
-                                                                      bool use_sculpt_pbvh)
+                                                                      int interp)
 {
   const DRWContextState *draw_ctx = DRW_context_state_get();
   WORKBENCH_FORWARD_Shaders *sh_data = &e_data.sh_data[draw_ctx->sh_cfg];
@@ -160,7 +159,7 @@ WORKBENCH_MaterialData *workbench_forward_get_or_create_material_data(WORKBENCH_
   DRWShadingGroup *grp;
 
   /* Solid */
-  workbench_material_update_data(wpd, ob, mat, &material_template);
+  workbench_material_update_data(wpd, ob, mat, &material_template, color_type);
   material_template.object_id = OBJECT_ID_PASS_ENABLED(wpd) ? engine_object_data->object_id : 1;
   material_template.color_type = color_type;
   material_template.ima = ima;
@@ -173,10 +172,15 @@ WORKBENCH_MaterialData *workbench_forward_get_or_create_material_data(WORKBENCH_
     material = MEM_mallocN(sizeof(WORKBENCH_MaterialData), __func__);
 
     /* transparent accum */
-    grp = DRW_shgroup_create(wpd->shading.color_type == color_type ?
-                                 wpd->transparent_accum_sh :
-                                 wpd->transparent_accum_uniform_sh,
-                             psl->transparent_accum_pass);
+    /* select the correct transparent accum shader */
+    GPUShader *shader = (wpd->shading.color_type == color_type) ?
+                            wpd->transparent_accum_sh :
+                            wpd->transparent_accum_uniform_sh;
+    if (color_type == V3D_SHADING_TEXTURE_COLOR) {
+      shader = wpd->transparent_accum_textured_sh;
+    }
+
+    grp = DRW_shgroup_create(shader, psl->transparent_accum_pass);
     DRW_shgroup_uniform_block(grp, "world_block", wpd->world_ubo);
     DRW_shgroup_uniform_float_copy(grp, "alpha", material_template.alpha);
     DRW_shgroup_uniform_vec4(grp, "viewvecs[0]", (float *)wpd->viewvecs, 3);
@@ -199,8 +203,7 @@ WORKBENCH_MaterialData *workbench_forward_get_or_create_material_data(WORKBENCH_
     material->shgrp = grp;
 
     /* Depth */
-    if (workbench_material_determine_color_type(wpd, material->ima, ob, use_sculpt_pbvh) ==
-        V3D_SHADING_TEXTURE_COLOR) {
+    if (color_type == V3D_SHADING_TEXTURE_COLOR) {
       material->shgrp_object_outline = DRW_shgroup_create(sh_data->object_outline_texture_sh,
                                                           psl->object_outline_pass);
       GPUTexture *tex = GPU_texture_from_blender(material->ima, material->iuser, GL_TEXTURE_2D);
@@ -223,13 +226,16 @@ WORKBENCH_MaterialData *workbench_forward_get_or_create_material_data(WORKBENCH_
 static GPUShader *ensure_forward_accum_shaders(WORKBENCH_PrivateData *wpd,
                                                bool is_uniform_color,
                                                bool is_hair,
+                                               bool is_texture_painting,
                                                eGPUShaderConfig sh_cfg)
 {
   WORKBENCH_FORWARD_Shaders *sh_data = &e_data.sh_data[sh_cfg];
-  int index = workbench_material_get_accum_shader_index(wpd, is_uniform_color, is_hair);
+  int index = workbench_material_get_accum_shader_index(
+      wpd, is_uniform_color, is_hair, is_texture_painting);
   if (sh_data->transparent_accum_sh_cache[index] == NULL) {
     const GPUShaderConfigData *sh_cfg_data = &GPU_shader_cfg_data[sh_cfg];
-    char *defines = workbench_material_build_defines(wpd, is_uniform_color, is_hair);
+    char *defines = workbench_material_build_defines(
+        wpd, is_uniform_color, is_hair, is_texture_painting);
     char *transparent_accum_vert = workbench_build_forward_vert(is_hair);
     char *transparent_accum_frag = workbench_build_forward_transparent_accum_frag();
     sh_data->transparent_accum_sh_cache[index] = GPU_shader_create_from_arrays({
@@ -248,7 +254,7 @@ static GPUShader *ensure_forward_composite_shaders(WORKBENCH_PrivateData *wpd)
 {
   int index = OBJECT_OUTLINE_ENABLED(wpd) ? 1 : 0;
   if (e_data.composite_sh_cache[index] == NULL) {
-    char *defines = workbench_material_build_defines(wpd, false, false);
+    char *defines = workbench_material_build_defines(wpd, false, false, false);
     char *composite_frag = workbench_build_forward_composite_frag();
     e_data.composite_sh_cache[index] = DRW_shader_create_fullscreen(composite_frag, defines);
     MEM_freeN(composite_frag);
@@ -260,10 +266,14 @@ static GPUShader *ensure_forward_composite_shaders(WORKBENCH_PrivateData *wpd)
 void workbench_forward_choose_shaders(WORKBENCH_PrivateData *wpd, eGPUShaderConfig sh_cfg)
 {
   wpd->composite_sh = ensure_forward_composite_shaders(wpd);
-  wpd->transparent_accum_sh = ensure_forward_accum_shaders(wpd, false, false, sh_cfg);
-  wpd->transparent_accum_hair_sh = ensure_forward_accum_shaders(wpd, false, true, sh_cfg);
-  wpd->transparent_accum_uniform_sh = ensure_forward_accum_shaders(wpd, true, false, sh_cfg);
-  wpd->transparent_accum_uniform_hair_sh = ensure_forward_accum_shaders(wpd, true, true, sh_cfg);
+  wpd->transparent_accum_sh = ensure_forward_accum_shaders(wpd, false, false, false, sh_cfg);
+  wpd->transparent_accum_hair_sh = ensure_forward_accum_shaders(wpd, false, true, false, sh_cfg);
+  wpd->transparent_accum_uniform_sh = ensure_forward_accum_shaders(
+      wpd, true, false, false, sh_cfg);
+  wpd->transparent_accum_uniform_hair_sh = ensure_forward_accum_shaders(
+      wpd, true, true, false, sh_cfg);
+  wpd->transparent_accum_textured_sh = ensure_forward_accum_shaders(
+      wpd, false, false, true, sh_cfg);
 }
 
 void workbench_forward_outline_shaders_ensure(WORKBENCH_PrivateData *wpd, eGPUShaderConfig sh_cfg)
@@ -272,9 +282,9 @@ void workbench_forward_outline_shaders_ensure(WORKBENCH_PrivateData *wpd, eGPUSh
 
   if (sh_data->object_outline_sh == NULL) {
     const GPUShaderConfigData *sh_cfg_data = &GPU_shader_cfg_data[sh_cfg];
-    char *defines = workbench_material_build_defines(wpd, false, false);
-    char *defines_texture = workbench_material_build_defines(wpd, true, false);
-    char *defines_hair = workbench_material_build_defines(wpd, false, true);
+    char *defines = workbench_material_build_defines(wpd, false, false, false);
+    char *defines_texture = workbench_material_build_defines(wpd, true, false, false);
+    char *defines_hair = workbench_material_build_defines(wpd, false, true, false);
     char *forward_vert = workbench_build_forward_vert(false);
     char *forward_hair_vert = workbench_build_forward_vert(true);
 
@@ -503,7 +513,7 @@ static void workbench_forward_cache_populate_particles(WORKBENCH_Data *vedata, O
       workbench_material_get_image_and_mat(ob, part->omat, &image, &iuser, &interp, &mat);
       int color_type = workbench_material_determine_color_type(wpd, image, ob, false);
       WORKBENCH_MaterialData *material = workbench_forward_get_or_create_material_data(
-          vedata, ob, mat, image, iuser, color_type, interp, false);
+          vedata, ob, mat, image, iuser, color_type, interp);
 
       struct GPUShader *shader = (wpd->shading.color_type == color_type) ?
                                      wpd->transparent_accum_hair_sh :
@@ -533,6 +543,53 @@ static void workbench_forward_cache_populate_particles(WORKBENCH_Data *vedata, O
     }
   }
 }
+static void workbench_forward_cache_populate_texture_paint_mode(WORKBENCH_Data *vedata, Object *ob)
+{
+  WORKBENCH_StorageList *stl = vedata->stl;
+  WORKBENCH_PrivateData *wpd = stl->g_data;
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+
+  Scene *scene = draw_ctx->scene;
+  const bool use_sculpt_pbvh = BKE_sculptsession_use_pbvh_draw(ob, draw_ctx->v3d);
+  WORKBENCH_MaterialData *material;
+
+  /* Force workbench to render active object textured when in texture paint mode */
+  const ImagePaintSettings *imapaint = &scene->toolsettings->imapaint;
+
+  /* Single Image mode */
+  if (imapaint->mode == IMAGEPAINT_MODE_IMAGE) {
+    Image *image = imapaint->canvas;
+    int interp = (imapaint->interp == IMAGEPAINT_INTERP_LINEAR) ? SHD_INTERP_LINEAR :
+                                                                  SHD_INTERP_CLOSEST;
+    int color_type = workbench_material_determine_color_type(wpd, image, ob, use_sculpt_pbvh);
+    struct GPUBatch *geom = DRW_cache_mesh_surface_texpaint_single_get(ob);
+    material = workbench_forward_get_or_create_material_data(
+        vedata, ob, NULL, image, NULL, color_type, interp);
+
+    DRW_shgroup_call(material->shgrp, geom, ob);
+    DRW_shgroup_call(material->shgrp_object_outline, geom, ob);
+  }
+  else {
+    /* IMAGEPAINT_MODE_MATERIAL */
+    const int materials_len = MAX2(1, ob->totcol);
+    struct GPUBatch **geom_array = DRW_cache_mesh_surface_texpaint_get(ob);
+    for (int i = 0; i < materials_len; i++) {
+      if (geom_array != NULL && geom_array[i] != NULL) {
+        Material *mat;
+        Image *image;
+        ImageUser *iuser;
+        int interp;
+        workbench_material_get_image_and_mat(ob, i + 1, &image, &iuser, &interp, &mat);
+        int color_type = workbench_material_determine_color_type(wpd, image, ob, use_sculpt_pbvh);
+        material = workbench_forward_get_or_create_material_data(
+            vedata, ob, mat, image, iuser, color_type, interp);
+
+        DRW_shgroup_call(material->shgrp, geom_array[i], ob);
+        DRW_shgroup_call(material->shgrp_object_outline, geom_array[i], ob);
+      }
+    }
+  }
+}
 
 void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 {
@@ -571,8 +628,13 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
     const bool use_sculpt_pbvh = BKE_sculptsession_use_pbvh_draw(ob, draw_ctx->v3d);
     const int materials_len = MAX2(1, ob->totcol);
     const Mesh *me = (ob->type == OB_MESH) ? ob->data : NULL;
+    const bool use_texture_paint_drawing = workbench_is_object_in_texture_paint_mode(ob) && me &&
+                                           me->mloopuv;
 
-    if (!use_sculpt_pbvh && TEXTURE_DRAWING_ENABLED(wpd) && me && me->mloopuv) {
+    if (use_texture_paint_drawing) {
+      workbench_forward_cache_populate_texture_paint_mode(vedata, ob);
+    }
+    else if (!use_sculpt_pbvh && TEXTURE_DRAWING_ENABLED(wpd) && me && me->mloopuv) {
       struct GPUBatch **geom_array = DRW_cache_mesh_surface_texpaint_get(ob);
       for (int i = 0; i < materials_len; i++) {
         Material *mat;
@@ -582,7 +644,7 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
         workbench_material_get_image_and_mat(ob, i + 1, &image, &iuser, &interp, &mat);
         int color_type = workbench_material_determine_color_type(wpd, image, ob, use_sculpt_pbvh);
         material = workbench_forward_get_or_create_material_data(
-            vedata, ob, mat, image, iuser, color_type, interp, use_sculpt_pbvh);
+            vedata, ob, mat, image, iuser, color_type, interp);
         DRW_shgroup_call(material->shgrp_object_outline, geom_array[i], ob);
         DRW_shgroup_call(material->shgrp, geom_array[i], ob);
       }
@@ -597,7 +659,7 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 
       if (use_sculpt_pbvh) {
         material = workbench_forward_get_or_create_material_data(
-            vedata, ob, NULL, NULL, NULL, color_type, 0, use_sculpt_pbvh);
+            vedata, ob, NULL, NULL, NULL, color_type, 0);
         bool use_vcol = (color_type == V3D_SHADING_VERTEX_COLOR);
         /* TODO(fclem) make this call optional */
         DRW_shgroup_call_sculpt(material->shgrp_object_outline, ob, false, false, false);
@@ -611,7 +673,7 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
                                     DRW_cache_object_surface_get(ob);
         if (geom) {
           material = workbench_forward_get_or_create_material_data(
-              vedata, ob, NULL, NULL, NULL, color_type, 0, use_sculpt_pbvh);
+              vedata, ob, NULL, NULL, NULL, color_type, 0);
           /* TODO(fclem) make this call optional */
           DRW_shgroup_call(material->shgrp_object_outline, geom, ob);
           if (!is_wire) {
@@ -628,7 +690,7 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
         for (int i = 0; i < materials_len; ++i) {
           struct Material *mat = give_current_material(ob, i + 1);
           material = workbench_forward_get_or_create_material_data(
-              vedata, ob, mat, NULL, NULL, V3D_SHADING_MATERIAL_COLOR, 0, use_sculpt_pbvh);
+              vedata, ob, mat, NULL, NULL, V3D_SHADING_MATERIAL_COLOR, 0);
           shgrps[i] = material->shgrp;
         }
         /* TODO(fclem) make this call optional */
@@ -651,7 +713,7 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 
             Material *mat = give_current_material(ob, i + 1);
             material = workbench_forward_get_or_create_material_data(
-                vedata, ob, mat, NULL, NULL, V3D_SHADING_MATERIAL_COLOR, 0, use_sculpt_pbvh);
+                vedata, ob, mat, NULL, NULL, V3D_SHADING_MATERIAL_COLOR, 0);
             /* TODO(fclem) make this call optional */
             DRW_shgroup_call(material->shgrp_object_outline, mat_geom[i], ob);
             if (!is_wire) {
diff --git a/source/blender/draw/engines/workbench/workbench_materials.c b/source/blender/draw/engines/workbench/workbench_materials.c
index 76f035562e5..1473b7df279 100644
--- a/source/blender/draw/engines/workbench/workbench_materials.c
+++ b/source/blender/draw/engines/workbench/workbench_materials.c
@@ -41,13 +41,9 @@
 void workbench_material_update_data(WORKBENCH_PrivateData *wpd,
                                     Object *ob,
                                     Material *mat,
-                                    WORKBENCH_MaterialData *data)
+                                    WORKBENCH_MaterialData *data,
+                                    int color_type)
 {
-  /* When V3D_SHADING_TEXTURE_COLOR is active, use V3D_SHADING_MATERIAL_COLOR as fallback when no
-   * texture could be determined */
-  int color_type = wpd->shading.color_type == V3D_SHADING_TEXTURE_COLOR ?
-                       V3D_SHADING_MATERIAL_COLOR :
-                       wpd->shading.color_type;
   copy_v3_fl3(data->diffuse_color, 0.8f, 0.8f, 0.8f);
   copy_v3_v3(data->base_color, data->diffuse_color);
   copy_v3_fl3(data->specular_color, 0.05f, 0.05f, 0.05f); /* Dielectric: 5% reflective. */
@@ -59,6 +55,10 @@ void workbench_material_update_data(WORKBENCH_PrivateData *wpd,
     copy_v3_v3(data->diffuse_color, wpd->shading.single_color);
     copy_v3_v3(data->base_color, data->diffuse_color);
   }
+  else if (color_type == V3D_SHADING_ERROR_COLOR) {
+    copy_v3_fl3(data->diffuse_color, 0.8, 0.0, 0.8);
+    copy_v3_v3(data->base_color, data->diffuse_color);
+  }
   else if (color_type == V3D_SHADING_RANDOM_COLOR) {
     uint hash = BLI_ghashutil_strhash_p_murmur(ob->id.name);
     if (ob->id.lib) {
@@ -76,7 +76,7 @@ void workbench_material_update_data(WORKBENCH_PrivateData *wpd,
     data->alpha *= ob->color[3];
   }
   else {
-    /* V3D_SHADING_MATERIAL_COLOR */
+    /* V3D_SHADING_MATERIAL_COLOR or V3D_SHADING_TEXTURE_COLOR */
     if (mat) {
       data->alpha *= mat->a;
       if (SPECULAR_HIGHLIGHT_ENABLED(wpd)) {
@@ -97,13 +97,19 @@ void workbench_material_update_data(WORKBENCH_PrivateData *wpd,
 
 char *workbench_material_build_defines(WORKBENCH_PrivateData *wpd,
                                        bool is_uniform_color,
-                                       bool is_hair)
+                                       bool is_hair,
+                                       bool is_texture_painting)
 {
   char *str = NULL;
   bool use_textures = (wpd->shading.color_type == V3D_SHADING_TEXTURE_COLOR) && !is_uniform_color;
   bool use_vertex_colors = (wpd->shading.color_type == V3D_SHADING_VERTEX_COLOR) &&
                            !is_uniform_color;
 
+  if (is_texture_painting) {
+    use_textures = true;
+    use_vertex_colors = false;
+  }
+
   DynStr *ds = BLI_dynstr_new();
 
   if (wpd->shading.flag & V3D_SHADING_OBJECT_OUTLINE) {
@@ -130,7 +136,7 @@ char *workbench_material_build_defines(WORKBENCH_PrivateData *wpd,
   if (OBJECT_ID_PASS_ENABLED(wpd)) {
     BLI_dynstr_append(ds, "#define OBJECT_ID_PASS_ENABLED\n");
   }
-  if (MATDATA_PASS_ENABLED(wpd)) {
+  if (workbench_is_matdata_pass_enabled(wpd)) {
     BLI_dynstr_append(ds, "#define MATDATA_PASS_ENABLED\n");
   }
   if (NORMAL_VIEWPORT_PASS_ENABLED(wpd)) {
@@ -193,22 +199,27 @@ int workbench_material_get_composite_shader_index(WORKBENCH_PrivateData *wpd)
   SET_FLAG_FROM_TEST(index, wpd->shading.flag & V3D_SHADING_SHADOW, 1 << 2);
   SET_FLAG_FROM_TEST(index, wpd->shading.flag & V3D_SHADING_CAVITY, 1 << 3);
   SET_FLAG_FROM_TEST(index, wpd->shading.flag & V3D_SHADING_OBJECT_OUTLINE, 1 << 4);
-  SET_FLAG_FROM_TEST(index, MATDATA_PASS_ENABLED(wpd), 1 << 5);
+  SET_FLAG_FROM_TEST(index, workbench_is_matdata_pass_enabled(wpd), 1 << 5);
   BLI_assert(index < MAX_COMPOSITE_SHADERS);
   return index;
 }
 
 int workbench_material_get_prepass_shader_index(WORKBENCH_PrivateData *wpd,
                                                 bool is_uniform_color,
-                                                bool is_hair)
+                                                bool is_hair,
+                                                bool is_texture_painting)
 {
   bool use_textures = (wpd->shading.color_type == V3D_SHADING_TEXTURE_COLOR) && !is_uniform_color;
   bool use_vertex_colors = (wpd->shading.color_type == V3D_SHADING_VERTEX_COLOR) &&
                            !is_uniform_color;
+  if (is_texture_painting) {
+    use_textures = true;
+    use_vertex_colors = false;
+  }
   /* NOTE: change MAX_PREPASS_SHADERS accordingly when modifying this function. */
   int index = 0;
   SET_FLAG_FROM_TEST(index, is_hair, 1 << 0);
-  SET_FLAG_FROM_TEST(index, MATDATA_PASS_ENABLED(wpd), 1 << 1);
+  SET_FLAG_FROM_TEST(index, workbench_is_matdata_pass_enabled(wpd), 1 << 1);
   SET_FLAG_FROM_TEST(index, OBJECT_ID_PASS_ENABLED(wpd), 1 << 2);
   SET_FLAG_FROM_TEST(index, NORMAL_VIEWPORT_PASS_ENABLED(wpd), 1 << 3);
   SET_FLAG_FROM_TEST(index, MATCAP_ENABLED(wpd), 1 << 4);
@@ -220,11 +231,18 @@ int workbench_material_get_prepass_shader_index(WORKBENCH_PrivateData *wpd,
 
 int workbench_material_get_accum_shader_index(WORKBENCH_PrivateData *wpd,
                                               bool is_uniform_color,
-                                              bool is_hair)
+                                              bool is_hair,
+                                              bool is_texture_painting)
 {
   bool use_textures = (wpd->shading.color_type == V3D_SHADING_TEXTURE_COLOR) && !is_uniform_color;
   bool use_vertex_colors = (wpd->shading.color_type == V3D_SHADING_VERTEX_COLOR) &&
                            !is_uniform_color;
+  if (is_texture_painting) {
+    use_textures = true;
+    use_vertex_colors = false;
+    is_hair = false;
+  }
+
   /* NOTE: change MAX_ACCUM_SHADERS accordingly when modifying this function. */
   int index = 0;
   /* 2 bits FLAT/STUDIO/MATCAP + Specular highlight */
@@ -253,6 +271,13 @@ int workbench_material_determine_color_type(WORKBENCH_PrivateData *wpd,
   if (color_type == V3D_SHADING_VERTEX_COLOR && (me == NULL || me->mloopcol == NULL)) {
     color_type = V3D_SHADING_OBJECT_COLOR;
   }
+
+  /* Force V3D_SHADING_TEXTURE_COLOR for active object when in texture painting
+   * no matter the shading color that the user has chosen, when there is no
+   * texture we will render the object with the error color */
+  if (workbench_is_object_in_texture_paint_mode(ob)) {
+    color_type = ima ? V3D_SHADING_TEXTURE_COLOR : V3D_SHADING_ERROR_COLOR;
+  }
   return color_type;
 }
 
@@ -292,7 +317,7 @@ void workbench_material_shgroup_uniform(WORKBENCH_PrivateData *wpd,
                                         const bool deferred,
                                         const int interp)
 {
-  if (deferred && !MATDATA_PASS_ENABLED(wpd)) {
+  if (deferred && !workbench_is_matdata_pass_enabled(wpd)) {
     return;
   }
 
diff --git a/source/blender/draw/engines/workbench/workbench_private.h b/source/blender/draw/engines/workbench/workbench_private.h
index 3b62ed33e96..17144c4dc10 100644
--- a/source/blender/draw/engines/workbench/workbench_private.h
+++ b/source/blender/draw/engines/workbench/workbench_private.h
@@ -43,6 +43,7 @@
 
 #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)
 #define FLAT_ENABLED(wpd) (wpd->shading.light == V3D_LIGHTING_FLAT)
 #define STUDIOLIGHT_ENABLED(wpd) (wpd->shading.light == V3D_LIGHTING_STUDIO)
 #define MATCAP_ENABLED(wpd) (wpd->shading.light == V3D_LIGHTING_MATCAP)
@@ -81,8 +82,6 @@
    (!STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)))
 #define OBJECT_OUTLINE_ENABLED(wpd) (wpd->shading.flag & V3D_SHADING_OBJECT_OUTLINE)
 #define OBJECT_ID_PASS_ENABLED(wpd) (OBJECT_OUTLINE_ENABLED(wpd) || CURVATURE_ENABLED(wpd))
-#define MATDATA_PASS_ENABLED(wpd) \
-  (wpd->shading.color_type != V3D_SHADING_SINGLE_COLOR || MATCAP_ENABLED(wpd))
 #define NORMAL_VIEWPORT_COMP_PASS_ENABLED(wpd) \
   (MATCAP_ENABLED(wpd) || STUDIOLIGHT_ENABLED(wpd) || SHADOW_ENABLED(wpd))
 #define NORMAL_VIEWPORT_PASS_ENABLED(wpd) \
@@ -208,12 +207,14 @@ typedef struct WORKBENCH_PrivateData {
   struct GPUShader *prepass_hair_sh;
   struct GPUShader *prepass_uniform_sh;
   struct GPUShader *prepass_uniform_hair_sh;
+  struct GPUShader *prepass_textured_sh;
   struct GPUShader *composite_sh;
   struct GPUShader *background_sh;
   struct GPUShader *transparent_accum_sh;
   struct GPUShader *transparent_accum_hair_sh;
   struct GPUShader *transparent_accum_uniform_sh;
   struct GPUShader *transparent_accum_uniform_hair_sh;
+  struct GPUShader *transparent_accum_textured_sh;
   View3DShading shading;
   StudioLight *studio_light;
   const UserDef *preferences;
@@ -354,6 +355,32 @@ BLI_INLINE bool workbench_is_fxaa_enabled(WORKBENCH_PrivateData *wpd)
   }
 }
 
+/** Is texture paint mode enabled (globally) */
+BLI_INLINE bool workbench_is_in_texture_paint_mode(void)
+{
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+  return draw_ctx->object_mode == OB_MODE_TEXTURE_PAINT;
+}
+
+/** Is texture paint mode active for the given object */
+BLI_INLINE bool workbench_is_object_in_texture_paint_mode(Object *ob)
+{
+  const DRWContextState *draw_ctx = DRW_context_state_get();
+  if (ob->type == OB_MESH && (draw_ctx->obact == ob)) {
+    const enum eContextObjectMode mode = CTX_data_mode_enum_ex(
+        draw_ctx->object_edit, draw_ctx->obact, draw_ctx->object_mode);
+    return (mode == CTX_MODE_PAINT_TEXTURE);
+  }
+
+  return false;
+}
+
+BLI_INLINE bool workbench_is_matdata_pass_enabled(WORKBENCH_PrivateData *wpd)
+{
+  return (wpd->shading.color_type != V3D_SHADING_SINGLE_COLOR || MATCAP_ENABLED(wpd)) ||
+         workbench_is_in_texture_paint_mode();
+}
+
 /* workbench_deferred.c */
 void workbench_deferred_engine_init(WORKBENCH_Data *vedata);
 void workbench_deferred_engine_free(void);
@@ -383,8 +410,7 @@ WORKBENCH_MaterialData *workbench_forward_get_or_create_material_data(WORKBENCH_
                                                                       Image *ima,
                                                                       ImageUser *iuser,
                                                                       int color_type,
-                                                                      int interp,
-                                                                      bool use_sculpt_pbvh);
+                                                                      int interp);
 
 /* workbench_effect_aa.c */
 void workbench_aa_create_pass(WORKBENCH_Data *vedata, GPUTexture **tx);
@@ -422,19 +448,23 @@ void workbench_material_get_image_and_mat(
     Object *ob, int mat_nr, Image **r_image, ImageUser **r_iuser, int *r_interp, Material **r_mat);
 char *workbench_material_build_defines(WORKBENCH_PrivateData *wpd,
                                        bool is_uniform_color,
-                                       bool is_hair);
+                                       bool is_hair,
+                                       bool is_texture_painting);
 void workbench_material_update_data(WORKBENCH_PrivateData *wpd,
                                     Object *ob,
                                     Material *mat,
-                                    WORKBENCH_MaterialData *data);
+                                    WORKBENCH_MaterialData *data,
+                                    int color_type);
 uint workbench_material_get_hash(WORKBENCH_MaterialData *material_template, bool is_ghost);
 int workbench_material_get_composite_shader_index(WORKBENCH_PrivateData *wpd);
 int workbench_material_get_prepass_shader_index(WORKBENCH_PrivateData *wpd,
                                                 bool is_uniform_color,
-                                                bool is_hair);
+                                                bool is_hair,
+                                                bool is_texture_painting);
 int workbench_material_get_accum_shader_index(WORKBENCH_PrivateData *wpd,
                                               bool is_uniform_color,
-                                              bool is_hair);
+                                              bool is_hair,
+                                              bool is_texture_painting);
 void workbench_material_shgroup_uniform(WORKBENCH_PrivateData *wpd,
                                         DRWShadingGroup *grp,
                                         WORKBENCH_MaterialData *material,