updated demos -> ALT + mouse uses Maya-style controls, replaced BMF_Fonts by GLDebugFont

fix debug drawing of btMultiSphereShape
added box2d demo
added experimental gpu 2d demo

src/BulletMultiThreaded/btGpuUtilsSharedCode.h

@@ -0,0 +1,54 @@
+/*
+Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org
+Copyright (C) 2006, 2009 Sony Computer Entertainment Inc. 
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+//----------------------------------------------------------------------------------------
+
+// Shared code for GPU-based utilities
+
+//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+//  Keep this file free from Bullet headers
+//  will be compiled by both CPU and CUDA compilers
+//	file with definitions of BT_GPU_xxx should be included first
+//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+//----------------------------------------------------------------------------------------
+
+#include "btGpuUtilsSharedDefs.h"
+
+//----------------------------------------------------------------------------------------
+
+extern "C"
+{
+
+//----------------------------------------------------------------------------------------
+
+//Round a / b to nearest higher integer value
+int BT_GPU_PREF(iDivUp)(int a, int b)
+{
+    return (a % b != 0) ? (a / b + 1) : (a / b);
+} // iDivUp()
+
+//----------------------------------------------------------------------------------------
+
+// compute grid and thread block size for a given number of elements
+void BT_GPU_PREF(computeGridSize)(int n, int blockSize, int &numBlocks, int &numThreads)
+{
+    numThreads = BT_GPU_min(blockSize, n);
+    numBlocks = BT_GPU_PREF(iDivUp)(n, numThreads);
+} // computeGridSize()
+
+//----------------------------------------------------------------------------------------
+
+} // extern "C"