void _setMat33Scale(ref b2Mat33 mat, float xfactor, float yfactor)
{
mat.SetZero();
mat.ex.x = xfactor;
mat.ey.y = yfactor;
mat.ez.z = 1;
}
void _setMat33Translation(ref b2Mat33 mat, cpVect t)
{
mat.SetZero();
mat.ex.x = 1;
mat.ey.y = 1;
mat.ez.x = t.x;
mat.ez.y = t.y;
mat.ez.z = 1;
}
void _setMat33Rotation(ref b2Mat33 mat, float angle)
{
mat.SetZero();
float c = cp.cpfcos(angle), s = cp.cpfsin(angle);
mat.ex.x = c; mat.ey.x = -s;
mat.ex.y = s; mat.ey.y = c;
mat.ez.z = 1;
}