Re: [pygame] Bump mapping

[Jasper Phillips <jasper@peak.org>]

On Wed, 30 Jun 2004, Federico Di Gregorio wrote:

> Lì martedì, 2004/06/29 alle 15:41, -0700, Jasper Phillips ha scritto:
> > As I posted a while ago, I want a clothify filter that I can use on
> > dynamically created maps.  After some investigation I found that this was
> > equivalent to bump mapping a carefully crafted image, so I hacked gimp to
> > spit out a bump map it generated for clothify, made it seamless, and am
> > tiling that to bump-map my map-images.
> > 
> > This was rather slow, so I've set it up so that the "shade map" that the
> > bump-mapping algortihm calculates from the bump map can be saved as an
> > image which can just be applied without any undue arithmetic.  Much
> > faster, but still taking ~7 seconds for larger images.
> 
> you have a lot of math. have you tried psyco? that should speed-up your
> math a lot.

True, but the math is all in the area that can be precalculated, so I don't
really care if it's slow (and it sure is slow!).  I'm mostly worried about
code that a user will run, namely:

def shadeMap( surface, shadeSurf, elevation=55.0, compensate=False ):
    '''Bump map from a pre calculated shade map'''
    surfW,  surfH  = surface.get_size()
    shadeW, shadeH = shadeSurf.get_size()
    compensation   = sin(elevation)
    resultSurf     = pygame.Surface( surface.get_size() )
    for x in range( surfW ):
        for y in range( surfH ):
            r,g,b,a = surface.get_at( (x,y) )
            shade   = shadeSurf.get_at( (x%shadeW,y%shadeH) )[0]  # red
            if compensate:
                r = min( 255, r * shade / (255*compensation) )
                g = min( 255, g * shade / (255*compensation) )
                b = min( 255, b * shade / (255*compensation) )
            else:
                r = r * shade / 255
                g = g * shade / 255
                b = b * shade / 255
            resultSurf.set_at( (x,y), (r,g,b,a) )
    return resultSurf

Actually, now that I look at it in isolation there isn't much here beyond
the get_at()s and set_at()s.  I should just get off my lazy ass and try
surfarray. ;-)

-Jasper