On Mon, Jul 13, 2009 at 10:00 PM, Elliott Slaughter < elliottslaugh...@gmail.com> wrote:
> The information I get after using load-and-convert-image seems > contradictory: > > bytes-per-pixel 4 > rmask 0x00FF0000 > gmask 0x0000FF00 > bmask 0x000000FF > amask 0x00000000 > > Why is the alpha mask 0 if it is 4 bytes per pixel? > > If I try load-and-convert-image on my png image, SDL still switches to BGRA > ordering, but if I am careful, I can get the image to display properly > (since it keeps the alpha channel). The pastebin code above gives me a blue > image instead of a red one here :-) > Having thought about it a little more, here is my guess: SDL seems want the image to be BGRA, even though the source didn't have an alpha channel. So it adds an alpha channel and leaves a mask of 0. When I put the image into Open GL, 0 alpha is interpreted as transparent. When I hard code BGR ordering and 3 bytes per pixel, I do get something drawn on the screen (but it's just a jumble of color). So maybe all of the data is there, it just has this empty alpha byte for every pixel? Now how would I test this/fix it? -- Elliott Slaughter "Don't worry about what anybody else is going to do. The best way to predict the future is to invent it." - Alan Kay
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