3D View: new nethod of opengl selection

Intended to replace legacy GL_SELECT, without the limitations of
sample queries which can't access depth information.

This commit adds VIEW3D_SELECT_PICK_NEAREST and VIEW3D_SELECT_PICK_ALL
which access the depth buffers to detect whats under the pointer,
so initial selection is always the closest item.

The performance of this method depends a lot on the OpenGL
implementations glReadPixels.

Since reading depth can be slow, buffers are cached for object picking
so selecting re-uses depth data, performing 1 draw instead of 3
(for 24, 18, 10 px regions, picking with many items under the pointer).

Occlusion queries draw twice when picking nearest,
so worst case 6x draw calls per selection.

Even with these improvements occlusion queries is faster on AMD hardware.

Depth selection is disabled by default, toggle option under select method.
May enable by default if this works well on different hardware.

Reviewed as D2543

1 files changed, 46 insertions, 11 deletions

diff --git a/source/blender/editors/space_view3d/view3d_view.c b/source/blender/editors/space_view3d/view3d_view.c
index 20361b73e78..9d1a3633786 100644
--- a/source/blender/editors/space_view3d/view3d_view.c
+++ b/source/blender/editors/space_view3d/view3d_view.c
@@ -1170,18 +1170,24 @@ static void view3d_select_loop(ViewContext *vc, Scene *scene, View3D *v3d, ARegi
  *
  * \note (vc->obedit == NULL) can be set to explicitly skip edit-object selection.
  */
-short view3d_opengl_select(ViewContext *vc, unsigned int *buffer, unsigned int bufsize, const rcti *input, bool do_nearest)
+int view3d_opengl_select(
+        ViewContext *vc, unsigned int *buffer, unsigned int bufsize, const rcti *input,
+        int select_mode)
 {
 	Scene *scene = vc->scene;
 	View3D *v3d = vc->v3d;
 	ARegion *ar = vc->ar;
 	rcti rect;
-	short hits;
+	int hits;
 	const bool use_obedit_skip = (scene->obedit != NULL) && (vc->obedit == NULL);
-	const bool do_passes = do_nearest && GPU_select_query_check_active();
+	const bool is_pick_select = (U.gpu_select_pick_deph != 0);
+	const bool do_passes = (
+	        (is_pick_select == false) &&
+	        (select_mode == VIEW3D_SELECT_PICK_NEAREST) &&
+	        GPU_select_query_check_active());
+
+	char gpu_select_mode;
 
-	G.f |= G_PICKSEL;
-	
 	/* case not a border select */
 	if (input->xmin == input->xmax) {
 		/* seems to be default value for bones only now */
@@ -1190,7 +1196,38 @@ short view3d_opengl_select(ViewContext *vc, unsigned int *buffer, unsigned int b
 	else {
 		rect = *input;
 	}
-	
+
+	if (is_pick_select) {
+		if (is_pick_select && select_mode == VIEW3D_SELECT_PICK_NEAREST) {
+			gpu_select_mode = GPU_SELECT_PICK_NEAREST;
+		}
+		else if (is_pick_select && select_mode == VIEW3D_SELECT_PICK_ALL) {
+			gpu_select_mode = GPU_SELECT_PICK_ALL;
+		}
+		else {
+			gpu_select_mode = GPU_SELECT_ALL;
+		}
+	}
+	else {
+		if (do_passes) {
+			gpu_select_mode = GPU_SELECT_NEAREST_FIRST_PASS;
+		}
+		else {
+			gpu_select_mode = GPU_SELECT_ALL;
+		}
+	}
+
+	/* Re-use cache (rect must be smaller then the cached)
+	 * other context is assumed to be unchanged */
+	if (GPU_select_is_cached()) {
+		GPU_select_begin(buffer, bufsize, &rect, gpu_select_mode, 0);
+		GPU_select_cache_load_id();
+		hits = GPU_select_end();
+		goto finally;
+	}
+
+	G.f |= G_PICKSEL;
+
 	view3d_winmatrix_set(ar, v3d, &rect);
 	mul_m4_m4m4(vc->rv3d->persmat, vc->rv3d->winmat, vc->rv3d->viewmat);
 	
@@ -1202,10 +1239,7 @@ short view3d_opengl_select(ViewContext *vc, unsigned int *buffer, unsigned int b
 	if (vc->rv3d->rflag & RV3D_CLIPPING)
 		ED_view3d_clipping_set(vc->rv3d);
 	
-	if (do_passes)
-		GPU_select_begin(buffer, bufsize, &rect, GPU_SELECT_NEAREST_FIRST_PASS, 0);
-	else
-		GPU_select_begin(buffer, bufsize, &rect, GPU_SELECT_ALL, 0);
+	GPU_select_begin(buffer, bufsize, &rect, gpu_select_mode, 0);
 
 	view3d_select_loop(vc, scene, v3d, ar, use_obedit_skip);
 
@@ -1231,7 +1265,8 @@ short view3d_opengl_select(ViewContext *vc, unsigned int *buffer, unsigned int b
 	
 	if (vc->rv3d->rflag & RV3D_CLIPPING)
 		ED_view3d_clipping_disable();
-	
+
+finally:
 	if (hits < 0) printf("Too many objects in select buffer\n");  /* XXX make error message */
 
 	return hits;