These two lines have the three components(vectors) that are necessary to describe movement: position, velocity and acceleration:
- Objects have a position (pos).
- The position gets changed (add) by velocity (vel).
- The velocity gets changed (add) by acceleration (acc).
Of course to use it in a sketch, there is more to write than these two lines, but they contain the core concept. For example, this code from the course creates a circle that looks like it is falling, because it accelerates downward:
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