Fix #111561: Workbench-Next: Overlay in-front compositing

Copy the in-front depth buffer to `DefaultTextureList::depth_in_front` for
correct overlay compositing.

Pull Request: https://projects.blender.org/blender/blender/pulls/111630

source/blender/draw/engines/workbench/workbench_effect_antialiasing.cc

@@ -163,6 +163,8 @@ void AntiAliasingPass::sync(SceneResources &resources, int2 resolution)
   sample0_depth_tx_.ensure_2d(GPU_DEPTH24_STENCIL8,
                               resolution,
                               GPU_TEXTURE_USAGE_SHADER_READ | GPU_TEXTURE_USAGE_ATTACHMENT);
+  sample0_depth_in_front_tx_.ensure_2d(
+      GPU_DEPTH24_STENCIL8, resolution, GPU_TEXTURE_USAGE_ATTACHMENT);
 
   taa_accumulation_ps_.init();
   taa_accumulation_ps_.state_set(sample_ == 0 ? DRW_STATE_WRITE_COLOR :
@@ -251,6 +253,7 @@ void AntiAliasingPass::draw(Manager &manager,
                             SceneResources &resources,
                             int2 resolution,
                             GPUTexture *depth_tx,
+                            GPUTexture *depth_in_front_tx,
                             GPUTexture *color_tx)
 {
   auto draw_overlay_depth = [&](GPUTexture *target) {
@@ -287,9 +290,11 @@ void AntiAliasingPass::draw(Manager &manager,
 
   if (sample_ == 0) {
     draw_overlay_depth(sample0_depth_tx_);
+    GPU_texture_copy(sample0_depth_in_front_tx_, resources.depth_in_front_tx);
   }
   /* Copy back the saved depth buffer for correct overlays. */
   GPU_texture_copy(depth_tx, sample0_depth_tx_);
+  GPU_texture_copy(depth_in_front_tx, sample0_depth_in_front_tx_);
 
   if (!DRW_state_is_image_render() || last_sample) {
     smaa_weight_tx_.acquire(

source/blender/draw/engines/workbench/workbench_engine.cc

@@ -427,7 +427,10 @@ class Instance {
     });
   }
 
-  void draw(Manager &manager, GPUTexture *depth_tx, GPUTexture *color_tx)
+  void draw(Manager &manager,
+            GPUTexture *depth_tx,
+            GPUTexture *depth_in_front_tx,
+            GPUTexture *color_tx)
   {
     view.sync(DRW_view_default_get());
 
@@ -435,7 +438,8 @@ class Instance {
 
     if (scene_state.render_finished) {
       /* Just copy back the already rendered result */
-      anti_aliasing_ps.draw(manager, view, resources, resolution, depth_tx, color_tx);
+      anti_aliasing_ps.draw(
+          manager, view, resources, resolution, depth_tx, depth_in_front_tx, color_tx);
       return;
     }
 
@@ -455,18 +459,13 @@ class Instance {
     fb.bind();
     GPU_framebuffer_clear_depth_stencil(fb, 1.0f, 0x00);
 
-    if (!transparent_ps.accumulation_in_front_ps_.is_empty()) {
+    bool needs_depth_in_front = !transparent_ps.accumulation_in_front_ps_.is_empty() ||
+                                scene_state.sample == 0;
+    if (needs_depth_in_front) {
       resources.depth_in_front_tx.acquire(resolution,
                                           GPU_DEPTH24_STENCIL8,
                                           GPU_TEXTURE_USAGE_SHADER_READ |
                                               GPU_TEXTURE_USAGE_ATTACHMENT);
-      if (opaque_ps.gbuffer_in_front_ps_.is_empty()) {
-        /* Clear only if it wont be overwritten by `opaque_ps`. */
-        Framebuffer fb = Framebuffer("Workbench.Clear");
-        fb.ensure(GPU_ATTACHMENT_TEXTURE(resources.depth_in_front_tx));
-        fb.bind();
-        GPU_framebuffer_clear_depth_stencil(fb, 1.0f, 0x00);
-      }
     }
 
     opaque_ps.draw(
@@ -477,16 +476,20 @@ class Instance {
     volume_ps.draw(manager, view, resources);
     outline_ps.draw(manager, resources);
     dof_ps.draw(manager, view, resources, resolution);
-    anti_aliasing_ps.draw(manager, view, resources, resolution, depth_tx, color_tx);
+    anti_aliasing_ps.draw(
+        manager, view, resources, resolution, depth_tx, depth_in_front_tx, color_tx);
 
     resources.color_tx.release();
     resources.object_id_tx.release();
     resources.depth_in_front_tx.release();
   }
 
-  void draw_viewport(Manager &manager, GPUTexture *depth_tx, GPUTexture *color_tx)
+  void draw_viewport(Manager &manager,
+                     GPUTexture *depth_tx,
+                     GPUTexture *depth_in_front_tx,
+                     GPUTexture *color_tx)
   {
-    this->draw(manager, depth_tx, color_tx);
+    this->draw(manager, depth_tx, depth_in_front_tx, color_tx);
 
     if (scene_state.sample + 1 < scene_state.samples_len) {
       DRW_viewport_request_redraw();
@@ -568,7 +571,7 @@ static void workbench_draw_scene(void *vedata)
   }
   DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
   draw::Manager *manager = DRW_manager_get();
-  ved->instance->draw_viewport(*manager, dtxl->depth, dtxl->color);
+  ved->instance->draw_viewport(*manager, dtxl->depth, dtxl->depth_in_front, dtxl->color);
 }
 
 static void workbench_instance_free(void *instance)

source/blender/draw/engines/workbench/workbench_mesh_passes.cc

@@ -172,10 +172,10 @@ void OpaquePass::draw(Manager &manager,
     opaque_fb.bind();
 
     manager.submit(gbuffer_in_front_ps_, view);
-    if (resources.depth_in_front_tx.is_valid()) {
-      /* Only needed when transparent infront is needed */
-      GPU_texture_copy(resources.depth_in_front_tx, resources.depth_tx);
-    }
+  }
+
+  if (resources.depth_in_front_tx.is_valid()) {
+    GPU_texture_copy(resources.depth_in_front_tx, resources.depth_tx);
   }
 
   if (!gbuffer_ps_.is_empty()) {

source/blender/draw/engines/workbench/workbench_private.hh

@@ -509,6 +509,7 @@ class AntiAliasingPass {
   float weights_sum_ = 0;
 
   Texture sample0_depth_tx_ = {"sample0_depth_tx"};
+  Texture sample0_depth_in_front_tx_ = {"sample0_depth_in_front_tx"};
   GPUTexture *stencil_tx_ = nullptr;
 
   Texture taa_accumulation_tx_ = {"taa_accumulation_tx"};
@@ -550,6 +551,7 @@ class AntiAliasingPass {
             SceneResources &resources,
             int2 resolution,
             GPUTexture *depth_tx,
+            GPUTexture *depth_in_front_tx,
             GPUTexture *color_tx);
 };