Performance-wise, is it Necessary to Stop Drawing Textures That Aren't On Screen Anymore?

Question

I pretty much put the question in the title. Would it help performance-wise if I stopped drawing targets are aren't on the screen anymore? What I mean by this is:

if (textureLocation is on the screen)
{
    draw code here
}

Or it is so insignificant(if at all) that it doesn't matter?

Thanks,
Shyy

Answer 1

Depends. Ultimately spent time comes down to 3 things: sending data to the GPU, vertex shading, and pixel shading.

If the texture is located on a spritesheet that has other textures that are being drawn on screen and the offscreen draw call is within the same .Begin() .End() block as those others, it won't hurt performance since it takes just as long to send data and set the GPU up for the spritesheet. The 4 off-screen vertices will run through the vertex shader but that is not a bottle neck. The graphic pipeline culls offscreen objects between the vertex shader and pixel shader so it won't spend any time in the pixel shader

But if is a stand alone texture or in it's own .Begin() .End() block, it will cost time sending it's data to the GPU even though the GPU will cull it.

Whether it is significant or not only profiling can tell you.