Transparent FrameBuffer background in OpenGL

Question

I want to use glClear and glClearColor to fill a frame buffer with a colour including alpha transparency. However the framebuffer always renders as opaque when binded to a textu

Answer 1

The clear color alpha of the FBO must be equal to 0 :

glColorMask(TRUE, TRUE, TRUE, TRUE);
glClearColor(0, 0, 0, 0);
glClear(GL_COLOR_BUFFER_BIT);