Setting the alpha component of each pixel

SDL Development
#1

Hi all,

how can i set the alpha value for a pixel? I have a 32bit surface and i try
changing the value of the first byte of a pixel ( i OR it with FF000000) but
when i blit it i dont see it transparent…In the documentation about the
SDL_SetAlpha it says:

“If ‘alpha’ is non-zero, this function sets the alpha value for the entire
surface, as opposed to using the alpha component of each pixel.” so i guess
there is a way to change each pixels alpha?

TIA,

Dimitris

#2

Hi all,

how can i set the alpha value for a pixel? I have a 32bit surface and i try
changing the value of the first byte of a pixel ( i OR it with FF000000) but
when i blit it i dont see it transparent…In the documentation about the
SDL_SetAlpha it says:

“If ‘alpha’ is non-zero, this function sets the alpha value for the entire
surface, as opposed to using the alpha component of each pixel.” so i guess
there is a way to change each pixels alpha?

Look at the testalpha program in the test directory.

See ya!
-Sam Lantinga (slouken at devolution.com)

Lead Programmer, Loki Entertainment Software–
“Any sufficiently advanced bug is indistinguishable from a feature”
– Rich Kulawiec