[SDL] Best way to implement a simple "Framebuffer"

[Forest Hale]

Personally this is how I would approach it, assuming we have an SDL_Surface that has been created to point at our unsigned int fb[1024] array...

We can just convert the pixels like this.

Then we can scale up using the appropriate SDL blit function.

I could easily have written this routine to do the scale-up while processing pixels but it would be less efficient (assuming a hardware implementation of the SDL blit is used).

// this is in BGRA order (suitable for PC), regardless of native endian order.
const unsigned char colortable[16*4] =
{
0,0,0,255, // black
255,255,255,255, // white
0,0,135,255, // red
40,240,255,255, // cyan
200,70,200,255, // purple
0,255,0,255, // green
255,0,0,255, // blue
10,220,230,255, // yellow
85,155,230,255, // orange
0,70,100,255, // brown
120,120,255,255, // light red
50,50,50,255, // dark gray
100,100,100,255, // gray
100,255,170,255, // light green
240,160,10,255, // lblue
180,180,180,255, // light grad
};

// optimized routine for pixel conversion
const unsigned char *pixin = 6502memory + graphix_address; // get the base address of the pixels in the VM
const unsigned int *pal = (const unsigned int *)colortable; // get the palette we'll decode it with
unsigned int *pixout = fb; // get the output address (we have an SDL_Surface whose pixels pointer is this)
for (i = 0;i < 32*32;i++)
	pixout[i] = pal[pixin[i]];

-- 
LordHavoc
Author of DarkPlaces Quake1 engine - http://icculus.org/twilight/darkplaces
Co-designer of Nexuiz - http://alientrap.org/nexuiz
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