[gameprogrammer] Re: Map Collision

[Paul Smith <bob@pcs.uklinux.net>]

On Fri, 2004-06-18 at 22:16, Gregg Bolinger wrote:
> Ok, I search the archives and couldn't find what I was looking for.  I
> am just getting into game programming and am using SDL and C++.  I've
> done a lot of examples and am getting the hang of everything.  So I
> thought I would venture away from tutorials and try and make something
> of my own.
> 
> I know how to do sprite animation and generic collision detection of
> sprites.  And I know how to scroll a background.  What I don't know
> how to do is detect collision with background data.  For example, I am
> making a game sort of like spy hunter but with a NASCAR twist. 
> Anyway, I need to adjust the speed of my sprites when they come in
> contact with the side of the road.
> 
> Any information, links, tips on how to achieve this would be great.
> 

There's a couple of ways that spring to mind.  Firstly, you could use a
particular colour from the palette to draw a line between the road and
off-road areas, and detect that colour from the background data.

Or, you could double up on the background data by saving another set of
background data with just 2 colours, white for on road and black for off
road (perhaps using shades of grey to determine a friction
coefficient?).  If you use an image type with an alpha channel, you
could use the alpha channel to store the friction coefficient.

Or, you could store the co-ordinate of the left and right edge of the
road in a separate numerical file, and test to see when the car has hit
those co-ordinates.  There's really quite a lot of ways to attack the
problem :)

Hope this helps!

> Thanks.



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