Re: [pygame] Collision Resolver module

[kschnee <kschnee@xxxxxxxxxx>]

On Mon, 31 Dec 2007 03:20:43 -0500 (EST), sjbrown@xxxxxxxxx wrote:
> Hi all.
> 
> Here's a "collision resolver" module I've been working on.
> 
> A common problem in 2D games is trying to move a sprite in a direction
> (deltaX, deltaY) and then discovering that there is a solid object in the
> new position it wants to occupy, so you have to move it back to the edge
> of
> that solid object.


This kind of problem -- checking a _sprite_ for collisions -- is why I
don't think it's a good idea to have game objects based around sprites.
We're trying to represent a physical space, so having objects recorded in
terms of screen coordinates blurs the distinction between where something
is drawn and where it _is_. What if the screen scrolls? Suddenly all the
objects "move" even if they're not supposed to be moving.

What I've been doing is decoupling sprites from game entities. Doing that
has already paid off in an unexpected way. When I changed the tile size I
was using, making one unit of space represented by fewer pixels, I noticed
that my character seemed to run slower. It didn't, actually; its apparent
speed had automatically adjusted to the new tile size, without my having to
re-code it!