   Front-to-back blending problem...
  I'm trying to do volume rendering and sometimes I traverse the data front-to-back and sometimes back-to-front. Back-to-front compositing works fine:glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);but when I try front-to-back using this:glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);everything becomes white.I have 8 alpha bit planes  and I'm using pbuffers (I don't know if it matters). I am clearing the image with glClearColor(0,0,0,0) (I've tried with 0,0,0,1 without success anyway).Any ideas? PS.:I have asked the same question at opengl.org.
  by the way, I am using   glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_ALPHA );(I know, it is a cheap way to bump my thread...)   ;  Blended objects still draw to the depth buffer, thus the later objects are oculled by the first ones.Which is why u always render BLENDED stuffies back - front.With ALPHA_TESTING this is not true because alpha testing writes on the visible areas to the depth buffer.tryglDisable(GL_DEPTH_TEST);HOWEVER please not A-->B-->C all over each other is not the same as C-->B-->A or A-->C-->B because of the why Blending is done.   