I have been changing my particle system to work with inverted colors. Sounds easy but i found it tricky as i don’t clear the screen each frame to make a sort of accumulation buffer or soft effect, and therefore the alpha was a pain.
Anyhow in an effort to understand what was going wrong (it’s now all beautiful and i’ll soon have a fresh video of it) i very quickly put together this visual tool that shows all the GL_BLEND mode combinations. You can change the source RGBA values and the destination RGBA values and see all the possible results.
It’s not pretty, not great code, not an exempt for coders, blah blah blah. But i would be surprised if anyone could tell you exactly what the outcome of a set of SRC and DST colors and Modes would output. This tool does that.
If anyone wants to add to it there is a todo list in the source file. Compiled against of_preRelease_v0062_osxSL_FAT on OSX 10.6.x under XCode 4.
The button inputs are on screen.
Oh and if someone would sanity check this for blend mode correctness then that would be cool.