Summing steering forces

So far, we've been adding weighted steering forces together and applying forces when certain thresholds have been met, but what does all this really do to an agent's locomotion? The two most common techniques that are used to add different steering forces together are through a weighted sums approach or a priority-based approach.

Weighted sums

A weighted sums approach takes all the steering forces into account all the time using fixed coefficients that weigh each force against every other. While this is very intuitive with a small number of forces, it can get very hard to balance competing forces together when a large number of different steering forces are being used.

Typically, this should be your first approach to get the agents to move, but when complex situations need to be handled, it's better to go with a priority-based approach.

Priority-based forces

When dealing with priorities, only certain forces are taken into account based on some sort of priority or condition. For example, you can have a system that disregards all forces that are smaller than some amount or allow a round-robin style of applying forces, letting each force have a small fraction of time to apply the steering. Allowing a round robin approach can fix issues that appear in a weighted sums approach where steering forces cancel each other out and essentially leave the agent with no ability to move.

Neither the weighted sums nor the priority-based approach is perfect; both methods take a good amount of work to finely tune the agents to their expected locomotion behaviors.