The Spawn function's parameters

The last function signature that will need to be modified is the Spawn function. New values will be required to allow the Emitter to set the scale and rotation values when we spawn an individual particle. The float start_scale and float end_scale parameters are used to set the starting and ending scale multipliers when we generate the particle. The last parameter that's added is float rotation, which represents the angle the particle is moving based on the x and y velocities of this particular particle. The following is the new version of the function:

void Spawn( float x, float y, float velocity_x, float velocity_y,
             float start_scale, float end_scale, float rotation );