OpenGL Rotation - Local vs Global Axes

Question

So I\'ve got an object I\'m trying to rotate according to a Yaw, Pitch and Roll scheme, relative to the object\'s own local axes rather than the global space\'s axes. Accor

Answer 1

Garrick,

When you call glRotate(angle, x, y, z), it is rotating around the vector that you are passing into glRotate. The vector goes from (0,0,0) to (x,y,z).

If you want to rotate an object around the object's local axis, you need to glTranslate the object to origin, perform your rotation, and then translate it back to where it came from.

Here is an example:

//Assume your object has the following properties
sf::Vector3 m_rotation;
sf::Vector3 m_center;

//Here would be the rotate method
public void DrawRotated(sf::Vector degrees) {
  //Store our current matrix 
  glPushMatrix();

  //Everything will happen in the reverse order...
  //Step 3: Translate back to where this object came from
  glTranslatef(m_center.x, m_center.y, m_center.z);

  //Step 2: Rotate this object about it's local axis
  glRotatef(degrees.y, 0, 1.0, 0);
  glRotatef(degrees.z, 0, 0, 1.0);
  glRotatef(degrees.x, 1.0, 0, 0);

  //Step 1: Translate this object to the origin
  glTranslatef(-1*m_center.x, -1*m_center.y, -1*m_center.z);

  //Render this object rotated by degrees
  Render();

  //Pop this matrix so that everything we render after this
  // is not also rotated
  glPopMatrix();
}