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Asked: 2026-05-26T11:06:30+00:00

I render two quads with OpenGL with equal z. When I have DEPTH enabled

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I render two quads with OpenGL with equal z. When I have DEPTH enabled I get following image, but when it is off I get what I need one fruit over another. Is it possible to draw quads with equal z, as I want? My OGL settings:

glEnable(GL_BLEND); glEnable(GL_ALPHA_TEST); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

my trouble

EDIT sorry I forgot to mention that left topmost quad I call to render first, and I use orthographic

EDIT +1 when I render quads with different Z I get the same image, how to fix it?

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1 Answer

  1. Editorial Team

    The z-buffer doesn’t care about transparency and so you have to sort the drawing order of your quads by their approximate depth.

    I would change their depth to be different (you can use an orthographic projection to have them appear the same size) and then draw the further quad first.

    Also, it is never a good idea to draw two polygons at the same depth even without transparency because of z-fighting.

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