Example #1
0
/*
* Jacobian recursive worker method
*/
void Solver::computeJ(Matd &J, TransformNode *node, Vec4d &pos, Mat4d &trans) {

	// Get initial transform data
	std::vector<Transform *> transforms = node->mTransforms;

	// LEFT MATRIX
	Mat4d leftMat;
	leftMat.MakeDiag(1.0);	// identity
	for (int i = 0; i < transforms.size(); i++)
	{
		Transform *tr = transforms[i];
		// Only need to calculate if DOF
		if (tr->IsDof())
		{
			for (int j = 0; j < tr->GetDofCount(); j++)
			{
				// Get DOF
				Dof *dof = tr->GetDof(j);
				int dofId = dof->mId;

				// Add to our map
				leftMap[dofId] = leftMat;
			}
		}
		// Now update leftMat
		leftMat = leftMat * tr->GetTransform();
	}

	// RIGHT MATRIX
	Mat4d rightMat;
	rightMat.MakeDiag(1.0);	// identity
	for (int i = transforms.size()-1; i >= 0; i--)
	{
		Transform *tr = transforms[i];
		// Only need to calculate if DOF
		if (tr->IsDof())
		{
			for (int j = tr->GetDofCount()- 1; j >= 0 ; j--)
			{
				// Get DOF
				Dof *dof = tr->GetDof(j);
				int dofId = dof->mId;

				// Add to our map
				rightMap[dofId] = rightMat;
			}
		}
		// Now update leftMat
		rightMat = tr->GetTransform() * rightMat;
	}

	// JACOBIAN
	Mat4d pTrans = node->mParentTransform;

	// New identity matrix for later use
	Mat4d newTransform;
	newTransform.MakeDiag(1.0);

	for (int i = 0; i < transforms.size(); i++)
	{		
		// Check if DOF, if so compute derivative
		Transform *tr = transforms[i];
		if (tr->IsDof())
		{
			for (int j = 0; j < tr->GetDofCount(); j++)
			{
				Mat4d deriv = tr->GetDeriv(j);

				// Get row
				Dof * dof = tr->GetDof(j);
				int dofId = dof->mId;

				Mat4d leftMat = leftMap[dofId];
				Mat4d rightMat = rightMap[dofId];
				Vec4d value = pTrans * leftMat * deriv * rightMat * trans * pos;

				J[dofId] = value;
			}
		}

		newTransform = newTransform * tr->GetTransform();
	}
	// Calculate J[] values for parent if necessary
	TransformNode *parent = node->mParentNode;
	// If the parent is non-null and not the current node
	if (parent != NULL && parent != node)
	{
		newTransform = newTransform * trans;
		computeJ(J, parent, pos, newTransform);
	}
}