tweaked the particle demo a little bit

src/Bullet3Common/b3Random.h

@@ -17,6 +17,8 @@ subject to the following restrictions:
 #ifndef B3_GEN_RANDOM_H
 #define B3_GEN_RANDOM_H
 
+#include "b3Scalar.h"
+
 #ifdef MT19937
 
 #include <limits.h>
@@ -38,5 +40,11 @@ B3_FORCE_INLINE unsigned int b3rand()                   { return rand(); }
 
 #endif
 
+inline b3Scalar b3RandRange(b3Scalar minRange, b3Scalar maxRange)
+{
+	return (b3rand() / (b3Scalar(B3_RAND_MAX) + b3Scalar(1.0))) * (maxRange - minRange) + minRange;
+}
+
+
 #endif //B3_GEN_RANDOM_H
 

src/Bullet3OpenCL/BroadphaseCollision/b3GpuSapBroadphase.cpp

@@ -1000,6 +1000,7 @@ void  b3GpuSapBroadphase::calculateOverlappingPairs(int maxPairs)
 	//if (m_currentBuffer>=0)
 	//	return calculateOverlappingPairsHostIncremental3Sap();
 
+
 	B3_PROFILE("GPU 1-axis SAP calculateOverlappingPairs");
 
 	int axis = 0;
@@ -1149,6 +1150,7 @@ void  b3GpuSapBroadphase::calculateOverlappingPairs(int maxPairs)
 			clFinish(m_queue);
 		}
 
+		if (m_gpuSmallSortData.size())
 		{
 			B3_PROFILE("gpu radix sort\n");
 			m_sorter->execute(m_gpuSmallSortData);

src/Bullet3OpenCL/NarrowphaseCollision/b3ConvexHullContact.cpp

@@ -3056,6 +3056,7 @@ void GpuSatCollision::computeConvexConvexContactsGPUSAT( b3OpenCLArray<b3Int4>*
 						launcher.launch1D( num);
 						clFinish(m_queue);
 						numConcavePairs = m_numConcavePairsOut.at(0);
+						//printf("numConcavePairs=%d (max = %d\n",numConcavePairs,maxTriConvexPairCapacity);
 						
 						if (numConcavePairs > maxTriConvexPairCapacity)
 						{