Re: [pygame] Physics, collision detection etc?

[Peter Gebauer <peter.gebauer@xxxxxxxxxxxxxxxxxxxxx>]

Hello René.

The thing is, in a large world spanning 16000x10000 pixels that will be a 
huge mask. Even if I reduce the resolution of the mask alone it will be 
either top inprecise or still too large.

I don't want to write for OpenGL alone even though the plan is to use OpenGL 
as test output. My plan is to build a large world of 3 or 4-sided 
convex polygons that could be used to detect colliding with large shapes in 
that world.

The best way to do this is probably to expose some of Zhang Fan's physics 
code, much of the math involved is already there, it just lacks 
non-rectangular shapes and a nice Python API to access it.

/Peter

On 2008-10-09 (Thu) 11:41, René Dudfield wrote:
> hi,
> 
> Note, that you can find contact normals with the mask module. See mask example.
> 
> For some types of games, per pixel collision detection is fast enough.
>  It uses rect bounding boxes as a first pass, so mostly it's not much
> slower than rect collision detection.  Assuming you are working in 2d,
> and you cache the mask(not regenerating it every frame) that is.
> However the mask.from_surface routine is fairly fast, it could do with
> some more optimization.
> 
> For opengl, it'd be interesting to do it in a shader too... since then
> you could just reuse your drawing routines to draw your
> objects(sprites) into a buffer (each with a different color), then use
> a shader to find all of the contact normals.  That way your collision
> could be pixel perfect, even with different methods of
> drawing(cartoon, glow, and other shaders) where the polygon
> representation is not correct.
> 
> 
> cheers,
> 
> 
> 
> 
> On Wed, Oct 8, 2008 at 9:46 PM, Greg Ewing <greg.ewing@xxxxxxxxxxxxxxxx> wrote:
> > Nirav Patel wrote:
> >
> >> If the polygons are Surfaces or can be turned into Surfaces, they can
> >> be turned into Masks to do pixel collision.
> >>
> >> On Tue, Oct 7, 2008 at 11:21 AM, Peter Gebauer
> >> <peter.gebauer@xxxxxxxxxxxxxxxxxxxxx> wrote:
> >>
> >> > Yep, but as I said, I need to find colliding polygons, not pixels.
> >
> > Pixel collision isn't suitable for all purposes,
> > e.g. if you need to find contact normals for
> > physics calculations.
> >
>