Changeset 8393 for code/trunk/src/external/bullet/BulletCollision/CollisionShapes/btCylinderShape.cpp

Timestamp:

May 3, 2011, 5:07:42 AM (13 years ago)

Author:

rgrieder

Message:

Updated Bullet from v2.77 to v2.78.
(I'm not going to make a branch for that since the update from 2.74 to 2.77 hasn't been tested that much either).

You will HAVE to do a complete RECOMPILE! I tested with MSVC and MinGW and they both threw linker errors at me.

File:

• code/trunk/src/external/bullet/BulletCollision/CollisionShapes/btCylinderShape.cpp (modified) (2 diffs)

code/trunk/src/external/bullet/BulletCollision/CollisionShapes/btCylinderShape.cpp

@@ -48 +48 @@
 void    btCylinderShape::calculateLocalInertia(btScalar mass,btVector3& inertia) const
 {
-        //approximation of box shape, todo: implement cylinder shape inertia before people notice ;-)
+
+//Until Bullet 2.77 a box approximation was used, so uncomment this if you need backwards compatibility
+//#define USE_BOX_INERTIA_APPROXIMATION 1
+#ifndef USE_BOX_INERTIA_APPROXIMATION
+
+        /*
+        cylinder is defined as following:
+        *
+        * - principle axis aligned along y by default, radius in x, z-value not used
+        * - for btCylinderShapeX: principle axis aligned along x, radius in y direction, z-value not used
+        * - for btCylinderShapeZ: principle axis aligned along z, radius in x direction, y-value not used
+        *
+        */
+
+        btScalar radius2;       // square of cylinder radius
+        btScalar height2;       // square of cylinder height
+        btVector3 halfExtents = getHalfExtentsWithMargin();     // get cylinder dimension
+        btScalar div12 = mass / 12.f;
+        btScalar div4 = mass / 4.f;
+        btScalar div2 = mass / 2.f;
+        int idxRadius, idxHeight;
+
+        switch (m_upAxis)       // get indices of radius and height of cylinder
+        {
+                case 0:         // cylinder is aligned along x
+                        idxRadius = 1;
+                        idxHeight = 0;
+                        break;
+                case 2:         // cylinder is aligned along z
+                        idxRadius = 0;
+                        idxHeight = 2;
+                        break;
+                default:        // cylinder is aligned along y
+                        idxRadius = 0;
+                        idxHeight = 1;
+        }
+
+        // calculate squares
+        radius2 = halfExtents[idxRadius] * halfExtents[idxRadius];
+        height2 = btScalar(4.) * halfExtents[idxHeight] * halfExtents[idxHeight];
+
+        // calculate tensor terms
+        btScalar t1 = div12 * height2 + div4 * radius2;
+        btScalar t2 = div2 * radius2;
+
+        switch (m_upAxis)       // set diagonal elements of inertia tensor
+        {
+                case 0:         // cylinder is aligned along x
+                        inertia.setValue(t2,t1,t1);
+                        break;
+                case 2:         // cylinder is aligned along z
+                        inertia.setValue(t1,t1,t2);
+                        break;
+                default:        // cylinder is aligned along y
+                        inertia.setValue(t1,t2,t1);
+        }
+#else //USE_BOX_INERTIA_APPROXIMATION
+        //approximation of box shape
         btVector3 halfExtents = getHalfExtentsWithMargin();
 
@@ -58 +115 @@
                                         mass/(btScalar(12.0)) * (lx*lx + lz*lz),
                                         mass/(btScalar(12.0)) * (lx*lx + ly*ly));
-
+#endif //USE_BOX_INERTIA_APPROXIMATION
 }