Original Post
I'm performing a render operation, using GLSL, that stores unique values into an RGBA texture to be downloaded from the graphics memory and used in system memory. To store the values into a texture I'm using a framebuffer object, with attached RGBA color buffers. The problem I'm having is that, no matter what, the stored alpha component is max (1.0 -- all alpha component bits are 1). I try rendering to the main framebuffer, with the same result. I can use an empty GLSL program except for "gl_FragColor = vec4(0.0, 0.0, 0.0, 0.0)" and the alpha component is still max. The rgb components, however, do retain the correct values in the actual, and test, shader program. I'm not trying to do any blending, just store unique values in each of the four components for use later. From what I understand, it should be possible to store a value into the alpha component of gl_FragColor, without blending. I have asked this question before, but have done a lot more digging, revising, and tinkering, but have had no luck. Hopefully someone can see the error my ways or has an idea what I'm doing wrong. So, in short, is there a reason I would not be able to store a specified value into the alpha component of an output fragment?