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, 48 insertions, 0 deletions

diff --git a/source/blender/gpu/intern/gpu_select_private.h b/source/blender/gpu/intern/gpu_select_private.h
new file mode 100644
index 00000000000..631b8806af9
--- /dev/null
+++ b/source/blender/gpu/intern/gpu_select_private.h
@@ -0,0 +1,48 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2014 Blender Foundation.
+ * All rights reserved.
+ *
+ * Contributor(s): Antony Riakiotakis.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/gpu/intern/gpu_select_private.h
+ *  \ingroup gpu
+ *
+ * Selection implementations.
+ */
+
+/* gpu_select_pick */
+void gpu_select_pick_begin(unsigned int (*buffer)[4], unsigned int bufsize, const rcti *input, char mode);
+bool gpu_select_pick_load_id(unsigned int id);
+unsigned int gpu_select_pick_end(void);
+
+void gpu_select_pick_cache_begin(void);
+void gpu_select_pick_cache_end(void);
+bool gpu_select_pick_is_cached(void);
+void gpu_select_pick_cache_load_id(void);
+
+/* gpu_select_sample_query */
+void gpu_select_query_begin(unsigned int (*buffer)[4], unsigned int bufsize, const rcti *input, char mode, int oldhits);
+bool gpu_select_query_load_id(unsigned int id);
+unsigned int gpu_select_query_end(void);
+
+
+#define SELECT_ID_NONE ((unsigned int)0xffffffff)