Cornix

10-04-2013, 01:27 PM

Hi there.

I was fooling around with OpenGL a little and was just doing some random performance tests to see how far my hardware can go.

After creating random vertices for about one million triangles I still had a constant 60 frames per second. Which is nice.

However, I once tried to set the Z-coordinate for all vertices to 0.5 (x and y are still random) and suddenly the frame rate dropped like crazy. I hardly got 200 000 triangles until my frame rate started to drop.

The depth buffer function I used was GL_LESS. I use orthogonal projection by the way.

Why is that? What is causing so much trouble if all vertices share the same z position?

Thanks for all your answers.

I was fooling around with OpenGL a little and was just doing some random performance tests to see how far my hardware can go.

After creating random vertices for about one million triangles I still had a constant 60 frames per second. Which is nice.

However, I once tried to set the Z-coordinate for all vertices to 0.5 (x and y are still random) and suddenly the frame rate dropped like crazy. I hardly got 200 000 triangles until my frame rate started to drop.

The depth buffer function I used was GL_LESS. I use orthogonal projection by the way.

Why is that? What is causing so much trouble if all vertices share the same z position?

Thanks for all your answers.