How does Draw Call Work?

HornyRhino

Hey guys... i was just wondering how does draw call actually work??
Because i was reading up Modular Building. So does Draw Call read or "Render" information also of what is not seen or does it read or "Render" only what is seen in the screen?? for what i know it only renders what is seen on the screen or the render distance set in the engine... but i might be very wrong in this.

Jonathan

This is really engine-specific. It certainly depends on how your engine handles draw calls, how well/if command buffers are used, what optimizations your engine might due to the data you send it, etc. So really, knowing what does and does not constitute depends on the engine, and only in-engine tools, PIX, etc. can really tell you what is happening and where. In my time in the game industry, I've had to move between multiple engines, and one of the worst things you can do is always assume what's true for one engine is true for the next.

But basically, consider a "draw call" is the point at which the CPU feeds information to the GPU for what to render.

HornyRhino

ok. so another question i have is how can i tell if the engine i am using renders only what is seen on screen or everything even what is not on screen?? i am interested in using UDK3 so info on how to tell how draw call works on each engine would be much appreciated thanks.

Ben Apuna

Check this out:

http://udn.epicgames.com/Three/ViewModes.html#Occlusion%20Preview