Issue with boxColor and SDL_MapRGBA functions in SDL_gfx (c++)

Asked May 28 '13 at 21:05

Active May 28 '13 at 21:08

Viewed 647 times

I want to fill the screen with blue.

This function works :

boxColor(screen, 0, 0, 640, 640, 0x0000ffff);

this one doesn't :

boxColor(screen, 0, 0, 640, 640, SDL_MapRGBA(screen->format, 0, 0, 255, 255));

What am I missing with the second version? How does one use SDL_MAPRGBA in this context?

edited May 28 '13 at 21:08

sAnS

asked May 28 '13 at 21:05

Kalessar

Can you describe exactly what goes wrong? Compiler error, wrong colour, or something else? – Mats Petersson May 28 '13 at 22:01
oh, sorry, it just doesn't do anything. More precisely, the first function colors the screen in blue, whereas the second version doesn't have any effect whatsoever (no errors or anything) – Kalessar May 28 '13 at 22:18
So, the first step would be to figure out what `SDL_MapRGBA()` returns. Print it out as a hex number, perhaps? – Mats Petersson May 28 '13 at 22:30
cout << hex << SDL_MapRGBA(screen->format, 0, 0, 255, 255) << endl; outputs "1f" o_O – Kalessar May 28 '13 at 22:42
Then figure out what `screen->format` actually is, because `1f` doesn't seem right. – Mats Petersson May 28 '13 at 22:45
and if i use boxColor(screen, 0, 0, 640, 640, SDL_MapRGBA(screen->format, 0xff, 0xff, 0x00, 0xff)); , then the screen fills with blue... – Kalessar May 28 '13 at 22:46
Try printing screen->format->BitsPerPixel – Mats Petersson May 28 '13 at 22:54
and, if I put the rgba values in the wrong way round, it works as required : boxColor(screen, 0, 0, 640, 640, SDL_MapRGBA(screen->format, 255, 255, 0, 0)); – Kalessar May 28 '13 at 22:54
ah well, at least it works – Kalessar May 28 '13 at 22:55
But either the docs is wrong, or something is wrong in your SDL version. – Mats Petersson May 28 '13 at 23:02

0 Answers0