Checking the cost of our materials

In this recipe, we are going to be looking at the impact that our materials have on performance. So far, this introductory chapter has gone over the basics of the rendering pipeline—we've seen how to create a physically based material, understood what the different shading models were, and saw how light played a key role in the overall look of the final image. However, we can't yet move on without understanding the impact that our games or applications have on the machines that are running them.

The first thing that we need to be aware of is that some materials or effects are more expensive in terms of efficiency than others. Chances are you have already experienced that in the past—think, for example, about frames per second in video games. How many times a second our displays are updated by the hardware that runs them directly influences how the game plays and feels. There are many elements that affect performance, but one determining factor in that equation is how complex our materials are.
A different example, if your background is more closely tied to traditional offline renderers such as VRay or Corona, could be how the rendering times vary wildly depending on how complex the materials you are rendering are. Using subsurface scattering, complex translucency, or a combination of multiple advanced effects can take render times from minutes to hours.

The point is that we need to be able to control how performant the scene we are creating is. Unreal offers us several tools that allow us to see how expensive certain effects and materials are, and check where we should be optimizing our assets or where certain things aren't working. With that in mind, let's bring all of the assets we have previously created together and use those tools to check them out.