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/*
* Example program for the Allegro library, by Shawn Hargreaves.
*
* This program demonstrates how to manipulate the palette. It draws
* a set of concentric circles onto the screen and animates them by
* cycling the palette.
*/
#include "allegro.h"
int main()
{
PALETTE palette;
RGB temp;
int c;
allegro_init();
install_keyboard();
if (set_gfx_mode(GFX_AUTODETECT, 320, 200, 0, 0) != 0) {
if (set_gfx_mode(GFX_AUTODETECT, 640, 480, 0, 0) != 0) {
allegro_message("Error setting graphics mode\n%s\n", allegro_error);
return 1;
}
}
/* first set the palette to black to hide what we are doing */
set_palette(black_palette);
/* draw some circles onto the screen */
acquire_screen();
for (c=255; c>0; c--)
circlefill(screen, SCREEN_W/2, SCREEN_H/2, c, c);
release_screen();
/* fill our palette with a gradually altering sequence of colors */
for (c=0; c<64; c++) {
palette[c].r = c;
palette[c].g = 0;
palette[c].b = 0;
}
for (c=64; c<128; c++) {
palette[c].r = 127-c;
palette[c].g = c-64;
palette[c].b = 0;
}
for (c=128; c<192; c++) {
palette[c].r = 0;
palette[c].g = 191-c;
palette[c].b = c-128;
}
for (c=192; c<256; c++) {
palette[c].r = 0;
palette[c].g = 0;
palette[c].b = 255-c;
}
/* animate the image by rotating the palette */
while (!keypressed()) {
temp = palette[255];
for (c=255; c>0; c--)
palette[c] = palette[c-1];
palette[0] = temp;
set_palette(palette);
}
return 0;
}
END_OF_MAIN();
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