The size of a particle can be set here to change according to its speed in distance units per second.
Property: | Function: |
---|---|
Size | A curve defining the particle’s size over a speed range. |
Speed Range | The low and high ends of the speed range to which the size curve is mapped (speeds outside the range will map to the end points of the curve). |
There are some situations where particles are emitted with random speeds and the smallest particles should also be the ones that move fastest. For example, you would expect small pieces of debris to be accelerated more by an explosion than larger pieces. You can achieve effects like this using Size By Speed with a simple ramp curve that increases the size in proportion to the speed of the particle. (Note that this should not be used with Limit Velocity Over Lifetime unless you are sure you want particles to shrink as they slow down.)