GPU: Simplify select shaders.

The shaders are: `GPU_SHADER_3D_FLAT_SELECT_ID` and `GPU_SHADER_3D_UNIFORM_SELECT_ID`.
This commit allows the drawing of the mesh select ids to be done on a 32UI format texture.
This simplifies the shader that previously acted on the backbuffer and had to do an uint to rgba conversion.

Differential Revision: https://developer.blender.org/D4350

1 files changed, 49 insertions, 1 deletions

diff --git a/source/blender/editors/space_view3d/drawobject.c b/source/blender/editors/space_view3d/drawobject.c
index e6e0438164c..b976c231841 100644
--- a/source/blender/editors/space_view3d/drawobject.c
+++ b/source/blender/editors/space_view3d/drawobject.c
@@ -47,6 +47,8 @@
 
 #include "UI_resources.h"
 
+#include "DRW_engine.h"
+
 #include "view3d_intern.h"  /* bad level include */
 
 #include "../../draw/intern/draw_cache_impl.h"  /* bad level include (temporary) */
@@ -281,7 +283,7 @@ static void bbs_mesh_solid_faces(Scene *UNUSED(scene), Object *ob, const float w
 	bbs_mesh_face(geom_faces, true, world_clip_planes);
 }
 
-void draw_object_backbufsel(
+void draw_object_select_id(
         Depsgraph *depsgraph, Scene *scene, View3D *v3d, RegionView3D *rv3d, Object *ob,
         short select_mode)
 {
@@ -380,6 +382,52 @@ void draw_object_backbufsel(
 	GPU_matrix_set(rv3d->viewmat);
 }
 
+void draw_object_depth(RegionView3D *rv3d, Object *ob)
+{
+	GPU_matrix_mul(ob->obmat);
+	GPU_depth_test(true);
+
+	const float (*world_clip_planes)[4] = NULL;
+	if (rv3d->rflag & RV3D_CLIPPING) {
+		ED_view3d_clipping_local(rv3d, ob->obmat);
+		world_clip_planes = rv3d->clip_local;
+	}
+
+	switch (ob->type) {
+		case OB_MESH:
+			{
+				GPUBatch *batch;
+
+				Mesh *me = ob->data;
+
+				if (ob->mode & OB_MODE_EDIT) {
+					batch = DRW_mesh_batch_cache_get_edit_triangles(me);
+				}
+				else {
+					batch = DRW_mesh_batch_cache_get_surface(me);
+				}
+
+				DRW_mesh_batch_cache_create_requested(ob, me, NULL, false, true);
+
+				DRW_opengl_context_enable();
+				const eGPUShaderConfig sh_cfg = world_clip_planes ? GPU_SHADER_CFG_CLIPPED : GPU_SHADER_CFG_DEFAULT;
+				GPU_batch_program_set_builtin_with_config(batch, GPU_SHADER_3D_DEPTH_ONLY, sh_cfg);
+				if (world_clip_planes != NULL) {
+					bbs_world_clip_planes_from_rv3d(batch, world_clip_planes);
+				}
+
+				GPU_batch_draw(batch);
+				DRW_opengl_context_disable();
+			}
+			break;
+		case OB_CURVE:
+		case OB_SURF:
+			break;
+	}
+
+	GPU_matrix_set(rv3d->viewmat);
+}
+
 
 void ED_draw_object_facemap(
         Depsgraph *depsgraph, Object *ob, const float col[4], const int facemap)