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rgb555conv
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Always outputs rounded down and rounded up variants

This commit is contained in:
Alex Gentilucci 2020-05-29 20:27:16 -06:00
parent 939a9019aa
commit cc344d9e90
Signed by: nytpu
GPG Key ID: 144ADD49F173F5CE
2 changed files with 15 additions and 20 deletions
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8
README.md
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@ -1,13 +1,13 @@
# rgb555conv - converts 24 bit color to 15 bit color
I got tired of manually converting 24 bit hex colors (like `0xRRGGBB`) into 15
bit RGB555 colors (like `0b0BBBBBGGGGGRRRRR`) so I slapped this together to do
bit BGR555 colors (like `0b0BBBBBGGGGGRRRRR`) so I slapped this together to do
it for me. Be warned that the 4 character color it outputs is in BGR format
instead of RGB for use on the Game Boy Color and Game Boy Advance. It also
for use on the Game Boy Color and the Game Boy Advance instead of RGB. It also
outputs a 24 bit representation of the 15 bit color (still in `0xRRGGBB`) for
use in things like your sprite software.
If it outputs a rounded and unrounded variant, it's up to you to look at it and
decide which you like, because they may differ significantly.
It outputs a rounded down and rounded up variant, it's up to you to look at it
and decide which you like, because they may differ significantly.
## compiling:

27
main.c
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@ -21,28 +21,23 @@ int main (int argc, char *argv[])
printf(" Input, 24 bit color, 6 char hex: #%06X\n\n", in_888);
rgb888 split;
split.r = (in_888 & 0x00FF0000) >> 16;
split.g = (in_888 & 0x0000FF00) >> 8;
split.b = in_888 & 0x000000FF;
split.r = ((in_888 & 0x00FF0000) >> 16) & 0xF0;
split.g = ((in_888 & 0x0000FF00) >> 8) & 0xF0;
split.b = (in_888 & 0x000000FF) & 0xF0;
// Basic rounding
rgb888 rounded = split;
if (split.r & 4) rounded.r |= 8;
if (split.g & 4) rounded.g |= 8;
if (split.b & 4) rounded.b |= 8;
rgb888 rounded;
rounded.r = split.r | 8;
rounded.g = split.g | 8;
rounded.b = split.b | 8;
int16_t rgb555 = ((split.b & 0xF8) << 7) | ((split.g & 0xF8) << 2) | (split.r >> 3);
int16_t rgb555_rounded = ((rounded.b & 0xF8) << 7) | ((rounded.g & 0xF8) << 2) | (rounded.r >> 3);
if (rgb555 != rgb555_rounded) {
printf("Output, 15 bit color, 6 char hex, unrounded: #%06X\n", (uint32_t) ((split.r & 0xF8) << 16) | ((split.g & 0xF8) << 8) | (split.b & 0xF8));
printf("Output, 15 bit color, 6 char hex, rounded: #%06X\n", (uint32_t) ((rounded.r & 0xF8) << 16) | ((rounded.g & 0xF8) << 8) | (rounded.b & 0xF8));
printf("Output, 15 bit color, 6 char hex, rounded down: #%06X\n", (uint32_t) ((split.r & 0xF8) << 16) | ((split.g & 0xF8) << 8) | (split.b & 0xF8));
printf("Output, 15 bit color, 6 char hex, rounded up: #%06X\n", (uint32_t) ((rounded.r & 0xF8) << 16) | ((rounded.g & 0xF8) << 8) | (rounded.b & 0xF8));
printf("Output, 15 bit color, 4 char hex, unrounded: 0x%04X\n", rgb555);
printf("Output, 15 bit color, 4 char hex, rounded: 0x%04X\n", rgb555_rounded);
} else {
printf("Output, 15 bit color, 6 char hex: #%06X\n", (uint32_t) ((split.r & 0xF8) << 16) | ((split.g & 0xF8) << 8) | (split.b & 0xF8));
printf("Output, 15 bit color, 4 char hex: 0x%04X\n", rgb555);
}
printf("Output, 15 bit color, 4 char hex, rounded down: 0x%04X\n", rgb555);
printf("Output, 15 bit color, 4 char hex, rounded up: 0x%04X\n", rgb555_rounded);
return 0;
}