1. SDL Collide & Euphoria, eh, colliding...
A couple weeks back I entertained the idea of trying to learn C again.
The torpid tale that lies ahead is the exact reason I am going to put it
off until next year...
Ok, my current game project demands collision detection. This leaves
me a couple options; 1. Try to write a wrapper for an SDL lib or
2. Write one in euphoria. I played around with option one thinking it
would be trivial to build a dll and then write the simple wrapper for
it. After about 3 hours of wandering the source code and drooling on
myself I decided that compiling a dll is not a newb thing. My next idea
(and here is where I get real bright), was to just rewrite the entire
library into euphoria code. I thought, "yeah, maybe I'll learn
something." Needless to say here I am.
The good news is that I managed to rewrite everything but one function.
The actual "hunt for a pixel perfect collision" function. This is just
to 'C' omplicated for my sad little brain. The difficult part is that I
have no idea what it is doing in some places. Can someone with some SDL
+ C experience give me an Eu-ish description of this function?
Your help would be extremely appreciated. The offensive code:
int SDL_CollideTransparentPixelTest(SDL_Surface *surface,int u,int v)
{
int bpp = surface->format->BytesPerPixel;
/*here p is the address to the pixel we want to retrieve*/
Uint8 *p = (Uint8 *)surface->pixels + v * surface->pitch + u * bpp;
Uint32 pixelcolor;
switch(bpp)
{
case(1):
pixelcolor = *p;
break;
case(2):
pixelcolor = *(Uint16 *)p;
break;
case(3): -- How can I test for endian-ness in Eu?
if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
pixelcolor = p[0] << 16 | p[1] << 8 | p[2];
else
pixelcolor = p[0] | p[1] << 8 | p[2] << 16;
break;
case(4):
pixelcolor = *(Uint32 *)p;
break;
}
/*test whether pixels color == color of transparent pixels for that
surface*/
return (pixelcolor == surface->format->colorkey);
}
What the heck is with all this recasting and carrying on ?!? How do I
*recast* a dataobject in Eu? Does this require auditioning? ;)
I really wanted to do this on my own to learn it, a small step towards
learning how to wrap libraries, etc, etc. I just don't think I am going
to get anywhere without a kick in the right direction.
Thanks again!
