HANDS ON GUIDE

01 - Effects Physics

Effects Physics are purely aesthetic and don't change how a games plays in any way. Using Effects Physics might allow for more debris from explosions, or for trees that sway in the wind. Without a dedicated physics processor, both of these examples would be too computationally intensive to run in real time and at a constant frame rate in games.

Let’s look at a large, visually impressive explosion to see what physics can add. Currently, big explosions are limited by what the CPU can do, as it’s the CPU that generates the geometry that underpins the size and location of all the fragments of an object. If it splits into too many parts, your CPU will become bogged down with calculating how all the bits of metal and wood should break apart and move, causing a very noticeable hit to your frame rate.

With a dedicated physics processor, the CPU can hand over the work of calculating how all the fragments of debris will move, thus keeping your frame rate up.

However, note that in order for a wall to explode in a cloud of rubble and dust, the wall must be made up of many vertices (the geometrical lines that define an object’s shape). Typically a wall is made up of just a few vertices, creating a simple cuboid.

However, for a really impressive exploding wall, you want to have this simple cuboid comprise smaller sections, so when you launch a rocket at it, these smaller parts can break away and fall apart. These extra sections need to be created and modelled when the object is first created (they can’t be added only as and when a rocket hits the wall) which makes for extra work for the CPU, even if it then offloads the work of calculating how the wall will break apart to the physics processor

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