[gameprogrammer] Re: collision detection

[Bob Pendleton <bob@pendleton.com>]

On Mon, 2004-06-21 at 10:40, Roger D. Vargas wrote:
> I want to make some simple tests with terrain rendering in opengl and I
> would like to know where i can find some tutorial about basic collision
> detection. I want to achive 2 things: first convert mouse click
> coordinates to terrain coordinates 

Typically that is done through "picking". You have to provide names for
your opengl primitives and you do a sort of "fake" redraw to let the
hardware find named primitives within a certain distance of the cursor.
Then you cull all that mess to find the ones you want. Try googling on
the phrase "opengl picking". There are some good tutorials right at the
top of the search page.


> and second: correct object movement
> throug the map (going up and down in the hills and stop at walls)

Lots of ways to do that. Generally either a height map is used or a BSP
tree is used. If you know where you are you can look up the height in a
height map. Just interpolate between height map entries to find the
correct height. If you need perfect height, then use a BSP tree to
identify the primitive you are in and then interpolate to find the
height of your current location. 

Of course, if your terrain is stored as a height map, then the first
technique is the easiest and gives you perfect height information.

		Bob Pendleton

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