How do I make triangles layer in OpenGL?

Question

I wrote some code to load a .obj file one triangle at a time in 3d. Each of these triangles are placed in the correct location, and are given a random color. When the full shape is loaded some triangles, even though they are placed in front of the others, go to the back and are not seen.

http://postimg.org/image/ln31rhabd/

The website above shows how the triangles Behind the cone are showing up OVER the ones in-front. the cone is being looked at from a top-front angle.

What do I have to do to make the ones on top actually show up on top? Do they stack in the order that each triangle was created?

Answer 1

At the outset, i believe the problem is related to Depth Buffering. Try enabling z-buffering in by calling the following functions:

glDepthFunc(GL_LESS);
glEnable(GL_DEPTH_TEST);

And also, do check if you are clearing the z-buffers along with the color buffers.

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);