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      1 /*
      2 Bullet Continuous Collision Detection and Physics Library
      3 Copyright (c) 2003-2009 Erwin Coumans  http://bulletphysics.org
      4 
      5 This software is provided 'as-is', without any express or implied warranty.
      6 In no event will the authors be held liable for any damages arising from the use of this software.
      7 Permission is granted to anyone to use this software for any purpose,
      8 including commercial applications, and to alter it and redistribute it freely,
      9 subject to the following restrictions:
     10 
     11 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.
     12 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
     13 3. This notice may not be removed or altered from any source distribution.
     14 */
     15 
     16 
     17 #include "btCapsuleShape.h"
     18 
     19 #include "BulletCollision/CollisionShapes/btCollisionMargin.h"
     20 #include "LinearMath/btQuaternion.h"
     21 
     22 btCapsuleShape::btCapsuleShape(btScalar radius, btScalar height) : btConvexInternalShape ()
     23 {
     24 	m_shapeType = CAPSULE_SHAPE_PROXYTYPE;
     25 	m_upAxis = 1;
     26 	m_implicitShapeDimensions.setValue(radius,0.5f*height,radius);
     27 }
     28 
     29 
     30  btVector3	btCapsuleShape::localGetSupportingVertexWithoutMargin(const btVector3& vec0)const
     31 {
     32 
     33 	btVector3 supVec(0,0,0);
     34 
     35 	btScalar maxDot(btScalar(-BT_LARGE_FLOAT));
     36 
     37 	btVector3 vec = vec0;
     38 	btScalar lenSqr = vec.length2();
     39 	if (lenSqr < btScalar(0.0001))
     40 	{
     41 		vec.setValue(1,0,0);
     42 	} else
     43 	{
     44 		btScalar rlen = btScalar(1.) / btSqrt(lenSqr );
     45 		vec *= rlen;
     46 	}
     47 
     48 	btVector3 vtx;
     49 	btScalar newDot;
     50 
     51 	btScalar radius = getRadius();
     52 
     53 
     54 	{
     55 		btVector3 pos(0,0,0);
     56 		pos[getUpAxis()] = getHalfHeight();
     57 
     58 		vtx = pos +vec*(radius) - vec * getMargin();
     59 		newDot = vec.dot(vtx);
     60 		if (newDot > maxDot)
     61 		{
     62 			maxDot = newDot;
     63 			supVec = vtx;
     64 		}
     65 	}
     66 	{
     67 		btVector3 pos(0,0,0);
     68 		pos[getUpAxis()] = -getHalfHeight();
     69 
     70 		vtx = pos +vec*(radius) - vec * getMargin();
     71 		newDot = vec.dot(vtx);
     72 		if (newDot > maxDot)
     73 		{
     74 			maxDot = newDot;
     75 			supVec = vtx;
     76 		}
     77 	}
     78 
     79 	return supVec;
     80 
     81 }
     82 
     83  void	btCapsuleShape::batchedUnitVectorGetSupportingVertexWithoutMargin(const btVector3* vectors,btVector3* supportVerticesOut,int numVectors) const
     84 {
     85 
     86 
     87 	btScalar radius = getRadius();
     88 
     89 	for (int j=0;j<numVectors;j++)
     90 	{
     91 		btScalar maxDot(btScalar(-BT_LARGE_FLOAT));
     92 		const btVector3& vec = vectors[j];
     93 
     94 		btVector3 vtx;
     95 		btScalar newDot;
     96 		{
     97 			btVector3 pos(0,0,0);
     98 			pos[getUpAxis()] = getHalfHeight();
     99 			vtx = pos +vec*(radius) - vec * getMargin();
    100 			newDot = vec.dot(vtx);
    101 			if (newDot > maxDot)
    102 			{
    103 				maxDot = newDot;
    104 				supportVerticesOut[j] = vtx;
    105 			}
    106 		}
    107 		{
    108 			btVector3 pos(0,0,0);
    109 			pos[getUpAxis()] = -getHalfHeight();
    110 			vtx = pos +vec*(radius) - vec * getMargin();
    111 			newDot = vec.dot(vtx);
    112 			if (newDot > maxDot)
    113 			{
    114 				maxDot = newDot;
    115 				supportVerticesOut[j] = vtx;
    116 			}
    117 		}
    118 
    119 	}
    120 }
    121 
    122 
    123 void	btCapsuleShape::calculateLocalInertia(btScalar mass,btVector3& inertia) const
    124 {
    125 	//as an approximation, take the inertia of the box that bounds the spheres
    126 
    127 	btTransform ident;
    128 	ident.setIdentity();
    129 
    130 
    131 	btScalar radius = getRadius();
    132 
    133 	btVector3 halfExtents(radius,radius,radius);
    134 	halfExtents[getUpAxis()]+=getHalfHeight();
    135 
    136 	btScalar margin = CONVEX_DISTANCE_MARGIN;
    137 
    138 	btScalar lx=btScalar(2.)*(halfExtents[0]+margin);
    139 	btScalar ly=btScalar(2.)*(halfExtents[1]+margin);
    140 	btScalar lz=btScalar(2.)*(halfExtents[2]+margin);
    141 	const btScalar x2 = lx*lx;
    142 	const btScalar y2 = ly*ly;
    143 	const btScalar z2 = lz*lz;
    144 	const btScalar scaledmass = mass * btScalar(.08333333);
    145 
    146 	inertia[0] = scaledmass * (y2+z2);
    147 	inertia[1] = scaledmass * (x2+z2);
    148 	inertia[2] = scaledmass * (x2+y2);
    149 
    150 }
    151 
    152 btCapsuleShapeX::btCapsuleShapeX(btScalar radius,btScalar height)
    153 {
    154 	m_upAxis = 0;
    155 	m_implicitShapeDimensions.setValue(0.5f*height, radius,radius);
    156 }
    157 
    158 
    159 
    160 
    161 
    162 
    163 btCapsuleShapeZ::btCapsuleShapeZ(btScalar radius,btScalar height)
    164 {
    165 	m_upAxis = 2;
    166 	m_implicitShapeDimensions.setValue(radius,radius,0.5f*height);
    167 }
    168 
    169 
    170 
    171 
    172