[SDL] background / palette tricks

[David Olofson]

On Wednesday 07 November 2007, neil at cloudsprinter.com wrote:
[...]
> this is an issue that can only be decided by playing around alot.. i
> dont want something to distracting from the gameplay, but i dont
> want something completley static and dull.. this is why perhaps just
> a simple slow pallete changing effect, so things are moving but not
> so in your face.

I see. Well, I think I'd try the "double buffered procedural texture" 
approach first. It's pretty easy to get going, and it's the most 
efficient way of rendering "free form" procedural effects at low 
frame rates.

As to palette animation, I wouldn't go there; not these days... 
Indeed; it's easy to do with SDL (create an indexed 8 bpp surface and 
mess with the palette), but it's rather expensive to render, as the 
blitter has to convert pixel by pixel, looking colors up in the 
palette, converting them to the display pixel format. A hardware 
implementation could be extremely fast, but I don't know if any SDL 
backends support this, or if that feature is actually accelerated on 
your average video card. Either way, of the widely used backends it's 
pretty much only DirectX that offers any h/w acceleration at all, so 
you pretty much have to make things work without acceleration anyway.


//David Olofson - Programmer, Composer, Open Source Advocate

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