The SpreadAngle property determines the random angles that a particle may be emit. On emission, a random angle is selected uniformly using the range defined by SpreadAngle. For example, if the
ParticleEmitter/EmissionDirection is Top (+Y), then this
DataType/Vector2 describes the size of the random angle spread on the X/Z axes, in degrees. The particle is given a velocity based on the
ParticleEmitter/Speed in the chosen direction.
Below is an animation of two default ParticleEmitters. The foreground (closer) emitter has one of its SpreadAngle axes set to 90 degrees, so particles are emit randomly in an arc.
Setting one axis to 360 will cause particles to emit in all direction in a circle. Setting both to 360 will cause particles to emit in all directions in a sphere.
Creating a Particle Emitter from Scratch
This rather lengthy code sample shows how every property of a
ParticleEmitter can be set, including
DataType/ColorSequence properties. Below is how the ParticleEmitter should after every property is set. Try playing around with the different properties to customize how the effect looks!