Question

I’m developing a game that basically has its entire terrain made out of AABB boxes. I know the verticies, minimum, and maximum of each box. I also set up my camera like this:

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

glRotatef(Camera.rotx,1,0,0);
glRotatef(Camera.roty,0,1,0);
glRotatef(Camera.rotz,0,0,1);

glTranslatef(-Camera.x,-Camera.y,-Camera.z);

What I’m trying to do is basically find the cube the mouse is on. I thought about giving the mouse position a forward directional vector and simply iterating through until the ‘mouse bullet’ hits something. However this envolves interating through all objects several times. Is there a way I could do it by only iterating through all the objects once?

Thanks

Answer 1

This is usually referred to as ‘picking’ This here looks like a good gl based link

If that is tldr, then a basic algorithm you could use

1. sort objects by z (or keep them sorted by z, or depth buffer tricks etc)
2. iterate and do a bounds test, stopping when you hit the first one.