void OpenGLGuiHelper::createCollisionShapeGraphicsObject(btCollisionShape* collisionShape)
{
//already has a graphics object?
if (collisionShape->getUserIndex()>=0)
return;
btAlignedObjectArray<GLInstanceVertex> gfxVertices;
btAlignedObjectArray<int> indices;
btTransform startTrans;startTrans.setIdentity();
{
btAlignedObjectArray<btVector3> vertexPositions;
btAlignedObjectArray<btVector3> vertexNormals;
CollisionShape2TriangleMesh(collisionShape,startTrans,vertexPositions,vertexNormals,indices);
gfxVertices.resize(vertexPositions.size());
for (int i=0;i<vertexPositions.size();i++)
{
for (int j=0;j<4;j++)
{
gfxVertices[i].xyzw[j] = vertexPositions[i][j];
}
for (int j=0;j<3;j++)
{
gfxVertices[i].normal[j] = vertexNormals[i][j];
}
for (int j=0;j<2;j++)
{
gfxVertices[i].uv[j] = 0.5;//we don't have UV info...
}
}
}
if (gfxVertices.size() && indices.size())
{
int shapeId = registerGraphicsShape(&gfxVertices[0].xyzw[0],gfxVertices.size(),&indices[0],indices.size());
collisionShape->setUserIndex(shapeId);
}
}
void CollisionShape2TriangleMesh(btCollisionShape* collisionShape, const btTransform& parentTransform, btAlignedObjectArray<btVector3>& vertexPositions, btAlignedObjectArray<btVector3>& vertexNormals, btAlignedObjectArray<int>& indicesOut)
{
//todo: support all collision shape types
switch (collisionShape->getShapeType())
{
case SOFTBODY_SHAPE_PROXYTYPE:
{
//skip the soft body collision shape for now
break;
}
case STATIC_PLANE_PROXYTYPE:
{
//draw a box, oriented along the plane normal
const btStaticPlaneShape* staticPlaneShape = static_cast<const btStaticPlaneShape*>(collisionShape);
btScalar planeConst = staticPlaneShape->getPlaneConstant();
const btVector3& planeNormal = staticPlaneShape->getPlaneNormal();
btVector3 planeOrigin = planeNormal * planeConst;
btVector3 vec0, vec1;
btPlaneSpace1(planeNormal, vec0, vec1);
btScalar vecLen = 100.f;
btVector3 verts[4];
verts[0] = planeOrigin + vec0 * vecLen + vec1 * vecLen;
verts[1] = planeOrigin - vec0 * vecLen + vec1 * vecLen;
verts[2] = planeOrigin - vec0 * vecLen - vec1 * vecLen;
verts[3] = planeOrigin + vec0 * vecLen - vec1 * vecLen;
int startIndex = vertexPositions.size();
indicesOut.push_back(startIndex + 0);
indicesOut.push_back(startIndex + 1);
indicesOut.push_back(startIndex + 2);
indicesOut.push_back(startIndex + 0);
indicesOut.push_back(startIndex + 2);
indicesOut.push_back(startIndex + 3);
btVector3 triNormal = parentTransform.getBasis() * planeNormal;
for (int i = 0; i < 4; i++)
{
btVector3 vtxPos;
btVector3 pos = parentTransform * verts[i];
vertexPositions.push_back(pos);
vertexNormals.push_back(triNormal);
}
break;
}
case TRIANGLE_MESH_SHAPE_PROXYTYPE:
{
btBvhTriangleMeshShape* trimesh = (btBvhTriangleMeshShape*)collisionShape;
btVector3 trimeshScaling = trimesh->getLocalScaling();
btStridingMeshInterface* meshInterface = trimesh->getMeshInterface();
btAlignedObjectArray<btVector3> vertices;
btAlignedObjectArray<int> indices;
for (int partId = 0; partId < meshInterface->getNumSubParts(); partId++)
{
const unsigned char* vertexbase = 0;
int numverts = 0;
PHY_ScalarType type = PHY_INTEGER;
int stride = 0;
const unsigned char* indexbase = 0;
int indexstride = 0;
int numfaces = 0;
PHY_ScalarType indicestype = PHY_INTEGER;
//PHY_ScalarType indexType=0;
btVector3 triangleVerts[3];
meshInterface->getLockedReadOnlyVertexIndexBase(&vertexbase, numverts, type, stride, &indexbase, indexstride, numfaces, indicestype, partId);
btVector3 aabbMin, aabbMax;
for (int triangleIndex = 0; triangleIndex < numfaces; triangleIndex++)
{
unsigned int* gfxbase = (unsigned int*)(indexbase + triangleIndex * indexstride);
for (int j = 2; j >= 0; j--)
{
int graphicsindex = indicestype == PHY_SHORT ? ((unsigned short*)gfxbase)[j] : gfxbase[j];
if (type == PHY_FLOAT)
{
float* graphicsbase = (float*)(vertexbase + graphicsindex * stride);
triangleVerts[j] = btVector3(
graphicsbase[0] * trimeshScaling.getX(),
graphicsbase[1] * trimeshScaling.getY(),
graphicsbase[2] * trimeshScaling.getZ());
}
else
{
double* graphicsbase = (double*)(vertexbase + graphicsindex * stride);
triangleVerts[j] = btVector3(btScalar(graphicsbase[0] * trimeshScaling.getX()),
btScalar(graphicsbase[1] * trimeshScaling.getY()),
btScalar(graphicsbase[2] * trimeshScaling.getZ()));
}
}
indices.push_back(vertices.size());
vertices.push_back(triangleVerts[0]);
indices.push_back(vertices.size());
vertices.push_back(triangleVerts[1]);
indices.push_back(vertices.size());
vertices.push_back(triangleVerts[2]);
btVector3 triNormal = (triangleVerts[1] - triangleVerts[0]).cross(triangleVerts[2] - triangleVerts[0]);
btScalar dot = triNormal.dot(triNormal);
//cull degenerate triangles
if (dot >= SIMD_EPSILON * SIMD_EPSILON)
{
triNormal /= btSqrt(dot);
for (int v = 0; v < 3; v++)
{
btVector3 pos = parentTransform * triangleVerts[v];
indicesOut.push_back(vertexPositions.size());
vertexPositions.push_back(pos);
vertexNormals.push_back(triNormal);
}
}
}
}
break;
}
default:
{
if (collisionShape->isConvex())
{
btConvexShape* convex = (btConvexShape*)collisionShape;
{
btShapeHull* hull = new btShapeHull(convex);
hull->buildHull(0.0, 1);
{
//int strideInBytes = 9*sizeof(float);
//int numVertices = hull->numVertices();
//int numIndices =hull->numIndices();
for (int t = 0; t < hull->numTriangles(); t++)
{
btVector3 triNormal;
int index0 = hull->getIndexPointer()[t * 3 + 0];
int index1 = hull->getIndexPointer()[t * 3 + 1];
int index2 = hull->getIndexPointer()[t * 3 + 2];
btVector3 pos0 = parentTransform * hull->getVertexPointer()[index0];
btVector3 pos1 = parentTransform * hull->getVertexPointer()[index1];
btVector3 pos2 = parentTransform * hull->getVertexPointer()[index2];
triNormal = (pos1 - pos0).cross(pos2 - pos0);
triNormal.safeNormalize();
for (int v = 0; v < 3; v++)
{
int index = hull->getIndexPointer()[t * 3 + v];
btVector3 pos = parentTransform * hull->getVertexPointer()[index];
indicesOut.push_back(vertexPositions.size());
vertexPositions.push_back(pos);
vertexNormals.push_back(triNormal);
}
}
}
delete hull;
}
}
else
{
if (collisionShape->isCompound())
{
btCompoundShape* compound = (btCompoundShape*)collisionShape;
for (int i = 0; i < compound->getNumChildShapes(); i++)
{
btTransform childWorldTrans = parentTransform * compound->getChildTransform(i);
CollisionShape2TriangleMesh(compound->getChildShape(i), childWorldTrans, vertexPositions, vertexNormals, indicesOut);
}
}
else
{
if (collisionShape->getShapeType() == SDF_SHAPE_PROXYTYPE)
{
//not yet
}
else
{
btAssert(0);
}
}
}
}
};
}
