# Depth Test

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Hey I've loaded a model into my scene and it has a normal texture. When I load it I can see through it, so I enabled depth testing and then it disappeared. What can I do to fix this? Thanks

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Hi,

can you post some code, to see when u set the depth testing and which function you use. (post some pseudo code plz)

I don't understand why your model is transparent and with depth testing it disappears.
Do you set an alpha lesser than 1.0f ?
Do you set GL_BLENDING ?

neyna

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Ok, my blendFunc is Gl_ONE and GL_ALPHA_ONE, i think, something like that.

No I'm not enabling blending, if I do it changes all my colours. I don't really know why it does that.

Ok, the depth code...

???(1.0)
glEnable(GL_DEPTH_TEST)
glDepthFunc(GL_LEQUAL)

I haven't got my code here but there's also another method I call that I pass 1.0 into it. Not sure what it's called though.

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the other method is glClearDepth(1.0f); (function specifies the clear value for the depth buffer)

If you dont enable blending, you don't need a blendFunc. And GL_ONE and GL_ALPHA_ONE is not the commune way for doing blending. All depend what king of blending you do ! blending is a way to melt some colors. For exemple, if you have one yellow pixel and one blue pixel one over the other, u can have a green pixel but setting blending.
Transparency is a special use of blending and use the following parameters : (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)

initialization :
glClearDepth(1.0f);
glDepthFunc(GL_LEQUAL);

in ur draw code :
glEnable(GL_DEPTH_TEST);

it seems the good way of doing.

How did you set the perspective?
near and far plane are VERY important for z-buffer (it is in log2, so if near plane is near 0, the z-buffer has big problems with precision)

hope that helps

neyna

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Also, make sure that you're actually clearing the z-buffer
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

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Oh damm i forgot to mention it ...

But if is scene is static he should not have problems if he forgot it.

Keep us informed if you resolv your problem.

neyna

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