Hi all,
I'd just thought I'd post this here, so that anyone could find it easily
(until it's added into contrib or wherever suitable).
It's an implementation of Bullet's (the physics engine)
btStridingMeshInterface that allows one to use OSG::Geometry:s as source
data for collision meshes.
It places some restrictions on the OSG::Geometry (only triangles and
triangle strips and only floats) but it works well for VRML-loaded
meshes so I hope it'll be useful.
Enjoy. :)
Cheers,
/Marcus
// simple implementation of runtime asserts
#define ORZ_RUNTIME_ASSERT(e) if(e) throw std::runtime_error(#e);
#define ORZ_THROW_ASSERT(e) throw std::runtime_error(#e);
/** Exposes an OpenSG Geometry to the Bullet btStridingMeshInterface
Asserts if not Pnt3f for vertices and GLuint/GLushort for indices.
Bullet only supports triangles or tri-strips, so only those are allowed as
well.
*/
class OpenSGStridingMeshInterface : public btStridingMeshInterface
{
public:
static bool s_writeInfo;
OpenSGStridingMeshInterface(OSG::Geometry* geo);
virtual void getLockedVertexIndexBase(unsigned char **vertexbase, int&
numverts,
PHY_ScalarType& type, int& vertexStride, unsigned char **indexbase, int
& indexstride,
int& numfaces, PHY_ScalarType& indicestype, int subpart = 0);
virtual void getLockedReadOnlyVertexIndexBase(const unsigned char
**vertex_base,
int& vertex_count, PHY_ScalarType& vertex_type, int& vertex_stride,
const unsigned char **index_base,
int& index_stride, int& triangle_count, PHY_ScalarType& index_type, int
subpart = 0) const;
virtual void unLockVertexBase(int subpart);
virtual void unLockReadOnlyVertexBase(int subpart) const;
virtual int getNumSubParts() const;
virtual void preallocateVertices(int numverts);
virtual void preallocateIndices(int numindices);
private:
OSG::GeometryRefPtr m_geo;
};
OpenSGStridingMeshInterface::OpenSGStridingMeshInterface(OSG::Geometry* geo) :
m_geo(geo)
{
// check geo formats and data validity
ORZ_RUNTIME_ASSERT(m_geo->getTypes()->size() ==
m_geo->getLengths()->size());
ORZ_RUNTIME_ASSERT(m_geo->getPositions()->getFormat() == GL_FLOAT);
ORZ_RUNTIME_ASSERT(m_geo->getPositions()->getDimension() == 3);
GLenum format = m_geo->getIndices()->getFormat();
ORZ_RUNTIME_ASSERT(format == GL_UNSIGNED_SHORT || format ==
GL_UNSIGNED_INT);
if (s_writeInfo) {
std::cout << m_geo << " " << m_geo->getLengths()->size() << " subparts"
<< std::endl;
}
}
void OpenSGStridingMeshInterface::getLockedVertexIndexBase(unsigned char
**vertexbase, int& numverts,
PHY_ScalarType& type, int& vertexStride, unsigned char **indexbase, int &
indexstride,
int& numfaces, PHY_ScalarType& indicestype, int subpart)
{
ORZ_THROW_ASSERT("No writing of OpenSG data allowed");
}
void OpenSGStridingMeshInterface::getLockedReadOnlyVertexIndexBase(const
unsigned char **vertex_base,
int& vertex_count, PHY_ScalarType& vertex_type, int& vertex_stride, const
unsigned char **index_base,
int& index_stride, int& triangle_count, PHY_ScalarType& index_type, int
subpart) const
{
// setup vertices and assert format
*vertex_base = reinterpret_cast<const unsigned char
*>(m_geo->getPositions()->getData());
vertex_count = m_geo->getPositions()->size();
vertex_type = PHY_FLOAT;
vertex_stride = sizeof(GLfloat) * 3;
// setup indices and assert format
GLenum index_format = m_geo->getIndices()->getFormat();
index_type = index_format == GL_UNSIGNED_SHORT ? PHY_SHORT : PHY_INTEGER;
size_t index_size = index_format == GL_UNSIGNED_SHORT ? sizeof(GLushort) :
sizeof(GLuint);
*index_base = reinterpret_cast<const unsigned char
*>(m_geo->getIndices()->getData());
// adjust indexbase to current part
for (int i = 0; i < subpart; ++i) {
// using std::accumulate would've been nice, but we don't have enough
type info here
*index_base += m_geo->getLengths()->getValue(i) * index_size;
}
GLenum triangle_type = m_geo->getTypes()->getValue(subpart);
ORZ_RUNTIME_ASSERT(triangle_type == GL_TRIANGLES || triangle_type ==
GL_TRIANGLE_STRIP);
// compute # of triangles
if (triangle_type == GL_TRIANGLE_STRIP) {
triangle_count = m_geo->getLengths()->getValue(subpart) - 2;
} else {
triangle_count = m_geo->getLengths()->getValue(subpart) / 3;
}
// set stride
index_stride = (triangle_type == GL_TRIANGLE_STRIP ? 1 : 3) * index_size;
// write mesh part info
if (s_writeInfo) {
std::cout << m_geo << " # " << subpart << ": " <<
triangle_count << " " << (triangle_type == GL_TRIANGLE_STRIP ?
"striped " : "discrete") <<
" triangles from " << m_geo->getLengths()->getValue(subpart) << "
indices" << std::endl;
}
}
void OpenSGStridingMeshInterface::unLockVertexBase(int subpart) { /* no locking
*/ }
void OpenSGStridingMeshInterface::unLockReadOnlyVertexBase(int subpart) const {
/* no locking */ }
int OpenSGStridingMeshInterface::getNumSubParts() const { return
m_geo->getLengths()->size(); }
void OpenSGStridingMeshInterface::preallocateVertices(int numverts) { /* no
prealloc */ }
void OpenSGStridingMeshInterface::preallocateIndices(int numindices) { /* no
prealloc */ }
bool OpenSGStridingMeshInterface::s_writeInfo = false;
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