CODEWITHSUNDEEP
opengl-es
johnbakers
johnbakers

Reputation: 24770

Enabling depth test causes nothing at all to appear

I have a depth buffer and am rendering a cone on the screen. It works, but then I realized I had forgotten the standard enabling of depth testing, and when I turned it on, now nothing appears at all.

I only have this one object, a cone, in my scene, so nothing else is in front of it.

The depth buffer is setup fine:

glFramebufferRenderbuffer(GL_FRAMEBUFFER,
                              GL_DEPTH_ATTACHMENT,
                              GL_RENDERBUFFER,
                              m_depthRenderbuffer);

The I bind the render buffer:

glBindRenderbuffer(GL_RENDERBUFFER, m_renderbuffer);

Then I render the cone:

enter image description here

(My experiments with this messy cone are the subject of another question I shall ask shortly).

But, as soon as I add this next line after creating the depth buffer and binding the render buffer:

glEnable(GL_DEPTH_TEST)

...then my cone magically disappears. There is nothing, not even a little dot, on the screen.

Why would that be?

Upvotes: 3

Views: 3060

Answers (3)

Mykhailo
Mykhailo

Reputation: 1

I've faced the same issue and the reason was that glDepthMask was set to GL_FALSE before calling glClear(GL_DEPTH_BUFFER_BIT). So in addition to the above comments/answers just make sure that glDepthMask is set to GL_TRUE before clearing the depth buffer.

Upvotes: 0

Caleb Marcum
Caleb Marcum

Reputation: 31

As fuzzyTew brought up in the comments (Apr 26, 2017), some people may have the issue where the near clipping distance was set to 0. I set this to 0.01 * cam_distance and everything was just dandy.

[...] My near clipping distance was set to 0. Turns out it needs to be positive. – fuzzyTew Apr 26 '17 at 20:25

Upvotes: 2

D-rk
D-rk

Reputation: 5919

When using GL_DEPTH_TEST,

glClear(GL_DEPTH_BUFFER_BIT) has to be called before rendering so that the depth buffer is initialized correctly.

Upvotes: 10

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