Heya, I must be having one of those days because I am stumped, I am trying the following…
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
glBlendColorEXT(transp.r, transp.g, transp.b, transp.a);
glBlendEquationSeparateEXT(GL_FUNC_ADD, GL_MAX);
glBlendFuncSeparateEXT( GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_COLOR, GL_ZERO, GL_CONSTANT_COLOR);
I have my color channels working fine but I have been unable to get my expected results in the alpha channel. What I would expect to see is 1.0’s everywhere from the glClear() except where I draw geometry where there should be transp.a?? Yet instead I get an alpha of 1.0 everywhere (no transp.a is not 1.0).
So to then simplify things I attempted…
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
glBlendColorEXT(transp.r, transp.g, transp.b, transp.a);
glBlendEquationSeparateEXT(GL_FUNC_ADD, GL_MAX);
glBlendFuncSeparateEXT( GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_COLOR, GL_ZERO, GL_ZERO);
With GL_ZERO in both srcAlpha and destAlpha you would expect to get 0.0 in alpha everywhere I draw geometry (max(0.0S, 0.0D) = 0.0) and 1.0 everywhere else (from the clear)… yet I still get 1.0 everywhere.
The color channel however is fine, I get the expected color results.
Anyone have any ideas?
(I am using an Nvidia Quadro FX 4400 with driver 7.7.1.8)