in my app I want/have to render clouds with impostors, so I somehow have to render the cloud as texture.
This works fine, also copying it from the framebuffer to texture (glCopyTexSubImage2D()), but the alpha does not work, what you see is a cloud on a quad with black background, not at all transparent.
I guess, for alpha to work the framebuffer has to be in GLX_RGBA format (attrib list for glxChooseVisual() ), and there has to be a “GLX_ALPHA_SIZE, 1” in it. But when i put it there, the programm crashes due to inability to create a visual context for OpenGL.
Also I read somewhere that the framebuffer HAS to be in 32 bit RGBA format, not 24 and not 16 but definitely 32. How do I achieve this? Someone once told me that under linux, rendering with more than 16b color is not possible at all… if this is true, I guess that cloud impostoring with linux is impossible?
Can someone help and explain?