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void Display::drawBone(Bone *pBone,int skelNum)
{
	static float z_dir[3] = {0., 0., 1.};
	float r_axis[3], mag, theta;

	//Tranform (rotate) from the local coordinate system of this bone to it's parent
	//This step corresponds to doing: ModelviewMatrix = M_k * (rot_parent_current)
	glMultMatrixd((double*)&pBone->rot_parent_current);     

	//Draw the local coordinate system for the selected bone.
	if(pBone->idx == m_SpotJoint)
		draw_bone_axis();

	//rotate AMC 
	//This step corresponds to doing: ModelviewMatrix *= R_k+1
	if(pBone->doftz) glTranslatef(0.,0.,pBone->tz);
	if(pBone->dofty) glTranslatef(0.,pBone->ty,0.);
	if(pBone->doftx) glTranslatef(pBone->tx,0.,0.);
	
	
	if(pBone->dofz) glRotatef(pBone->drz, 0., 0., 1.);
	if(pBone->dofy) glRotatef(pBone->dry, 0., 1,  0.);
	if(pBone->dofx) glRotatef(pBone->drx, 1., 0., 0.);

	glColor3f(1., 1., 0.1);

	//Store the current ModelviewMatrix (before adding the translation part)
	glPushMatrix();

	//Compute tx, ty, tz - translation from pBone to it's child (in local coordinate system of pBone)
	float tx = pBone->dir[0]*pBone->length;
	float ty = pBone->dir[1]*pBone->length;
	float tz = pBone->dir[2]*pBone->length;


	// Use the current ModelviewMatrix to display the current bone
	// Rotate the bone from its canonical position (elongated sphere 
	// with its major axis parallel to X axis) to its correct orientation
	if(pBone->idx == root)
		glCallList(m_BoneList[skelNum] + pBone->idx);
	else
	{ 
		//translate to the center of the bone
		glTranslatef(tx/2.0, ty/2.0, tz/2.0);

		//Compute the angle between the canonical pose and the correct orientation 
		//(specified in pBone->dir) using cross product.
		//Using the formula: r_axis = z_dir x pBone->dir
		
		v3_cross(z_dir, pBone->dir, r_axis);

		theta =  GetAngle(z_dir, pBone->dir, r_axis);
		
		glRotatef(theta*180./M_PI, r_axis[0], r_axis[1], r_axis[2]);;
		glCallList(m_BoneList[skelNum] + pBone->idx);
	}

	glPopMatrix(); 

	// Finally, add the translation component to the ModelviewMatrix
	// This step corresponds to doing: M_k+1 = ModelviewMatrix += T_k+1
	glTranslatef(tx, ty, tz);

}