I was having a problem with manipulation matrices in GL that I was hoping someone could help me with.
I have a 3D engine, and I used to move the camera via the orbit method, that is rotating it around the origin of the world.
I decided to play around some and move the camera more like a fly through, similar to a flight simulator, but I wasn’t able to get the behavior I want.
I want to have all delta’s to rotation apply to the current camera view orienation. That is I want forward motion to be in the direction of the camera as well as have the delta rotations apply to the camera orientation. So I can look up(rotation around camera x-axis) move forward, look to the left and move that direction, rotate the camera around it’s z axis etc.
Do do this I intitialize the matrix with gluLookat, grab the matrix and then do the following. (Currently I only include the rotation around the x and y axis…
// Get the current matrix
matrix2 = m_engine_state->GetMatrix();
// now do delta stuff…
glRotatef(m_engine_state->rotx180/M_PI, 1, 0, 0);glRotatef(m_engine_state->roty180/M_PI, 0, 1, 0);
// save current state for next time through
glGetFloatv(GL_MODELVIEW_MATRIX, (float *)matrix);
This doesn’t quit work, it seems the rotations are always around the origin of the world not the camera. So I figured, I have the order wrong, so I changed things around, Loaded matrix, then performed the rotations and translation, this actually was worse, I ended up not moving in the direction I was facing,
In the other way I did the following
// then do rotations and translation
Then saved the current matrix for next time.
I assume I’m doing something wrong, any ideas.
One thought I had is to use the second method but change the translation to not be in the z direction but calculate the xyz components, but is seems like I should be able to do this easier. I want the following
- have all rotations relative to the current camera position
- movement will be in the direction the camera is facing.