Scene Graph to Open GL

A scene graph can be translated into direct rendering commands by following these simple guide lines:

• Apply the camera transformation first
• Walk the graph depth-first (by always keeping one hand on the “railing”).
• Whenever a transformation node is traversed down-wards, remember the actual modelling transformation (by issuing a glPushMatrix command). Then apply the respective local transformation.
• Whenever a geometry node is traversed down-wards, render it with the actual modelling transformation.
• Whenever a transformation node is traversed up-wards, restore the previous modelling transformation (by issuing a glPopMatrix command).

For example the following scene graph

is translated into the following direct OpenGL command sequence