Hi folks, im doing some simple alpha blending and it is giving me some serious head ache. Hopefully someone can point me in the right direction. Some background. I have a simple scene consiting of land, a river and a log on the river. I want to make my river to be transparent to give an illusion of water. Everything is textured. Without alpha blending, everything works fine. To enable alpha blending I perform the following: glEnable(GL_BLEND); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LESS); Next, to make an object (my river) transparent, before drawing my quads i wrote: glColor4f(0.0f,0.0f,0.0f,0.5f); glBlendFunc(GL_ONE,GL_ONE); Hurray, my river was now transparent runnuig along some land. On a side note, without the above 2 lines my water was magically transparent (by only enabling GL_BLEND).... this caused me to worry slightly. However, I now need to place a log on the river and no matter what I do, the log appear 50% transparent, as in half of the log is opaque like I want, the other half has blending applied. The following picture describes the problem better: What am I doing wrong, I tried to turn off blending for my log by using glColor4f(0.0f,0.0f,0.0f, 0.0f); This did not work. I am construct my scene as follows: Log Land Water Please, anyone, i am going nuts over this :) Any help apprecicated. Taz

To turn off alpha blending, use glDisable(GL_BLEND)

Quote:Original post by irreversible
To turn off alpha blending, use glDisable(GL_BLEND)

But i want alpha blending to allow me to have transparent water?

Or am i incorrect here.

Kind regards
Taz

enable depth testing

disable blending
draw terrain
draw log
enable blending
draw water


OpenGL is a state machine - GL_BLEND is just a state that can be toggled at any time using glEnable() and glDisable().