I am having a problem with blending modes. My bitmap font resides in an image with white letters and black background, so that I can occlude the black when I draw the text.
I use glBlendFunc(GL_SRC_ALPHA, GL_ONE) to get rid of the black background. I apply a colour to the font by changing the quad colour that the font characters are bound to, using glColor3f(). However, I have a background image some of which is white. When text is drawn on top of this (no matter what colour) is does not show up. I know it is the blending because when I turn blending off the text appears with the correct colour (albeit with the black background - the occlusion of which was the whole point in using blending in the first place).
For white areas will I have to change the blending function, or is there an all-encompasing solution? I’m relatively new to blending modes so I’m unsure of how best to proceed.
Thanks in advance for any help.
[edit]I’m not sure if it matters but I’m drawing the background using glDrawPixels() and as mentioned the font characters are mapped on coloured quads. The background is drawn first, then I turn off depth testing to draw the font.[/edit]
[This message has been edited by sckoobs (edited 11-12-2003).]