Occlusion Query based selection.

This patch creates an interface for selection mechanisms in opengl. This
makes it possible to switch between occlusion query based or select
rendermode based selection transparently.

This is really useful on graphics drivers that do not accelerate the
select rendermode path (some ATI cards are notorious for this, and the
new path is used by default there), since occlusion queries are always
hardware accelerated due to their use in games.

The option can be found under system - selection. Auto just enables
occlusion queries for ATI users while the rest of the options enforce
one of the two methods always.

There is just one known change, previous code enforced nearest bone to
always get selected, even when mouse selecting near the same position, I
couldn't replicate the behaviour though.

patch by me with edits and review by Campbell.

Thanks!

1 files changed, 61 insertions, 0 deletions

diff --git a/source/blender/gpu/GPU_select.h b/source/blender/gpu/GPU_select.h
new file mode 100644
index 00000000000..1a274e0ad9d
--- /dev/null
+++ b/source/blender/gpu/GPU_select.h
@@ -0,0 +1,61 @@
+/*
+ * ***** 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 GPU_select.h
+ *  \ingroup gpu
+ */
+
+#ifndef __GPU_SELECT__
+#define __GPU_SELECT__
+
+#include "DNA_vec_types.h"  /* rcft */
+#include "BLI_sys_types.h"
+
+/* flags for mode of operation */
+enum {
+	GPU_SELECT_ALL                      = 1,
+	GPU_SELECT_NEAREST_FIRST_PASS       = 2,
+	GPU_SELECT_NEAREST_SECOND_PASS      = 3,
+};
+
+/* initialize and provide buffer for results */
+void GPU_select_begin(unsigned int *buffer, unsigned int bufsize, rctf *input, char mode, int oldhits);
+
+/* loads a new selection id and ends previous query, if any. In second pass of selection it also returns
+ * if id has been hit on the first pass already. Thus we can skip drawing un-hit objects IMPORTANT: We rely on the order of object rendering on passes to be
+ * the same for this to work */
+bool GPU_select_load_id(unsigned int id);
+
+/* cleanup and flush selection results to buffer. Return number of hits and hits in buffer.
+ * if dopass is true, we will do a second pass with occlusion queries to get the closest hit */
+unsigned int GPU_select_end(void);
+
+/* does the GPU support occlusion queries? */
+bool GPU_select_query_check_support(void);
+
+/* is occlusion query supported and user activated? */
+bool GPU_select_query_check_active(void);
+
+#endif