I am loading a .obj model with assimp.
Simple models work fine, but as soon as I make something like a taurus, I get some back faces appearing.

http://imgur.com/4xKDiYX

The part where I turn depth testing on is:

	glEnable(GL_CULL_FACE);
	glCullFace(GL_BACK);
	glFrontFace(GL_CCW);
	
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LEQUAL);

(I'm clearing both the colour and depth buffer)
Any guess about what I'm messing up?

(I'll post or link more code if needed later)

Just for clarification: Back face culling and depth buffer are two completely independent features of OpenGL.

I suspect that the two get in the way of each other in your code.

Try to disable back face culling and rely solely on the depth buffer. Is it getting better or worse?

Try reversing the winding order?

post near nad far plane values of your projection matrix. In general, you should tweek them so that f/n is close to 24 bit integer capability. Setting for example near value to 0.0001 and far value to 100000.0 will result in depth inaccuracy.

Try to disable back face culling and rely solely on the depth buffer. Is it getting better or worse?

If I turn off face culling, I get a lot more black strips. So, I'd say worse.

Try reversing the winding order?

The model was made in Blender.
If I reverse it when importing, the opposite places will appear coloured.
Can I do something like change it on the fly depending on which face is facing the light source ?

post near nad far plane values of your projection matrix. In general, you should tweek them so that f/n is close to 24 bit integer capability. Setting for example near value to 0.0001 and far value to 100000.0 will result in depth inaccuracy.

glm::mat4 p = glm::perspective(60.0f,1000*1.0f/600,0.1f,100.0f);

Much more conservative, I think.

http://imgur.com/4xKDiYX