DRW: Draw checkerboard alpha pattern for Cycles

Add checkerboard alpha pattern like it was in 2.79

3 files changed, 27 insertions, 13 deletions

diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index 43441aa7f00..5c88c1f93db 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -1136,9 +1136,8 @@ static void drw_engines_draw_background(void)
   }
 
   /* No draw_background found, doing default background */
-  if (DRW_state_draw_background()) {
-    DRW_draw_background();
-  }
+  const bool do_alpha_checker = !DRW_state_draw_background();
+  DRW_draw_background(do_alpha_checker);
 }
 
 static void drw_engines_draw_scene(void)
@@ -1487,6 +1486,7 @@ void DRW_draw_view(const bContext *C)
   drw_state_prepare_clean_for_draw(&DST);
   DST.options.draw_text = ((v3d->flag2 & V3D_HIDE_OVERLAYS) == 0 &&
                            (v3d->overlay.flag & V3D_OVERLAY_HIDE_TEXT) != 0);
+  DST.options.draw_background = scene->r.alphamode == R_ADDSKY;
   DRW_draw_render_loop_ex(depsgraph, engine_type, ar, v3d, viewport, C);
 }
 
@@ -2730,9 +2730,6 @@ bool DRW_state_draw_support(void)
  */
 bool DRW_state_draw_background(void)
 {
-  if (DRW_state_is_image_render() == false) {
-    return true;
-  }
   return DST.options.draw_background;
 }
 
diff --git a/source/blender/draw/intern/draw_view.c b/source/blender/draw/intern/draw_view.c
index 1543e381d8c..7aa2e007f79 100644
--- a/source/blender/draw/intern/draw_view.c
+++ b/source/blender/draw/intern/draw_view.c
@@ -61,19 +61,35 @@ void DRW_draw_region_info(void)
 
 /* ************************* Background ************************** */
 
-void DRW_draw_background(void)
+void DRW_draw_background(bool do_alpha_checker)
 {
   /* Just to make sure */
   glDepthMask(GL_TRUE);
   glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
   glStencilMask(0xFF);
 
-  if (UI_GetThemeValue(TH_SHOW_BACK_GRAD)) {
+  if (do_alpha_checker) {
+    /* Transparent render, do alpha checker. */
+    GPU_depth_test(false);
+
+    GPU_matrix_push();
+    GPU_matrix_identity_set();
+    GPU_matrix_identity_projection_set();
+
+    imm_draw_box_checker_2d(-1.0f, -1.0f, 1.0f, 1.0f);
+
+    GPU_matrix_pop();
+
+    GPU_clear(GPU_DEPTH_BIT | GPU_STENCIL_BIT);
+
+    GPU_depth_test(true);
+  }
+  else if (UI_GetThemeValue(TH_SHOW_BACK_GRAD)) {
     float m[4][4];
     unit_m4(m);
 
     /* Gradient background Color */
-    glDisable(GL_DEPTH_TEST);
+    GPU_depth_test(false);
 
     GPUVertFormat *format = immVertexFormat();
     uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
@@ -104,14 +120,15 @@ void DRW_draw_background(void)
 
     GPU_matrix_pop();
 
-    glClear(GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
+    GPU_clear(GPU_DEPTH_BIT | GPU_STENCIL_BIT);
 
-    glEnable(GL_DEPTH_TEST);
+    GPU_depth_test(true);
   }
   else {
     /* Solid background Color */
     UI_ThemeClearColorAlpha(TH_BACK, 1.0f);
-    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
+
+    GPU_clear(GPU_COLOR_BIT | GPU_DEPTH_BIT | GPU_STENCIL_BIT);
   }
 }
 
diff --git a/source/blender/draw/intern/draw_view.h b/source/blender/draw/intern/draw_view.h
index 08a8e984c87..715c3c0d40c 100644
--- a/source/blender/draw/intern/draw_view.h
+++ b/source/blender/draw/intern/draw_view.h
@@ -24,7 +24,7 @@
 #define __DRAW_VIEW_H__
 
 void DRW_draw_region_info(void);
-void DRW_draw_background(void);
+void DRW_draw_background(bool do_alpha_checker);
 void DRW_draw_cursor(void);
 void DRW_draw_gizmo_3d(void);
 void DRW_draw_gizmo_2d(void);