Question

Im building something in JOGL and im looking to make the camera move either through using the keyboard or mouse, it doesnt really matter, so long as the camera can pan around the object and possibly zoom in and out. If using the keyboard/mouse is difficult then I also dont mind using some buttons in the applications, e.g. arrows up, down, left and right and a plus and minus button for the zoom but basically whatevers easiest.
Im building something kind of like Lego but its proving to be quite difficult without being able to move the camera.

Answer 1

To move your “camera” you need to apply a glTranslate3f() transform at the beginning of your rendering function. If your camera’s location is to be

cameraPos = <cx, cy, cz>

then you should use

glTranslate3f( -cx, -cy, -cz );

This will offset everything that is drawn by that vector.

In order to use the keyboard to make this happen, you will want to use a KeyListener implementation and define the functions specified by the interface.

public void keyPressed( KeyEvent ke ){ // put something intelligent here... }
public void keyReleased( KeyEvent ke ){}
public void keyTyped( KeyEvent ke ){}

Make sure to register this implementing class as a KeyListener to your GLJPanel (or whatever you’re using). Then, inside the keyPressed(…) function, check which key is being pressed and increment the appropriate coordinate of the camera.

If you want to get really fancy and allow the mouse to enable you to look around, you can do a similar thing by creating a MouseMotionListener and registering it. The OpenGL transform that is needed to put this into play can vary based on what type of mouse behavior you are looking for. If you just want something simple that will allow you to look around, you can probably get away with tracking mouse motion in the x and y directions and allowing it to modify some offset angles. Moving the mouse in the x direction rotates about the y-axis. Movement in the y direction rotates about the x-axis. As an OpenGL call, as with the glTranslate3f(), you can use glRotatef() to rotate about each axis.

glRotatef( angleX, 1, 0, 0 ); // to rotate about the x-axis
glRotatef( angleY, 0, 1, 0 ); // to rotate about the y-axis

Again, this is just a quick and easy solution. It won’t be beautiful, but it will work. If you want to implement something a bit fancier, you can look into computing an arbitrary axis rotation matrix.

http://inside.mines.edu/~gmurray/ArbitraryAxisRotation/
(one of many resources on this topic)