Fills a color mapping table for customised effects.
Fills the specified color mapping table with lookup data for doing
customised effects with the specified palette, calling the blend function
to determine the results of each color combination.
Your blend routine will be passed a pointer to the palette and the two
indices of the colors which are to be combined, and should fill in the RGB
structure with the desired result in 0-63 format. Allegro will then search
the palette for the closest match to the RGB color that you requested, so
it doesn't matter if the palette has no exact match for this color.
If the callback function is not NULL, it will be called 256 times during
the calculation, allowing you to display a progress indicator. Example:
void return_grey_color(const PALETTE pal,
int x, int y, RGB *rgb)
/* Build a color lookup table for greyscale effect. */
The following projects include source code containing this keyword: