Re: [pygame] Using Numeric & Surfarray with alpha values

[Peter Shinners <pete@xxxxxxxxxxxx>]

On Sat, 2005-11-26 at 18:28 -0500, Mike Rotondo wrote:
> We are writing a 2D particle engine and we would like to render each 
> particle with gradually decreasing alpha values. However, our original 
> image for the particles has per-pixel alpha, so we can't use set-alpha. 
> So, we are going to have to modify each pixel's alpha value ith Numeric, 
> it seems.

> [[pixel and (pixel * particle.life / particle.decay) for pixl in row] 
> for row in array]

I'm a bit rusty with my surfarray mojo. I would think directly rendering
the particles is going to win over creating an offscreen temporary. In
fact it must be a pretty good speedup.

It looks like you may be dealing with one "particle" for every pixel? I
don't see how just dividing pixel alphas will move anything around?