Collision Spawn creates new particles from existing ones that collide with one or more Deflector space warps.
You can specify different post-collision behavior for the colliding particles and their offspring. Each spawned particle is born at the same location as its parent, and has the same orientation and shape. Collision Spawn can give the spawned particles a different speed and scaling factor. If you wire the Collision Spawn test to another event, spawned particles are sent to that event, where you can specify different properties for the new particles.
Examples of Collision Spawn usage include marks or explosions resulting from collisions between particles and objects. To achieve these effects, you can use Collision Spawn in conjunction with the Shape Mark and Shape Facing operators.
The Collision Spawn test supports the following deflector space warps:
Interface
The user interface appears in the parameters panel, on the right side of the Particle View dialog.
In the context of Collision Spawn, a parent is the original particle from which new particles are spawned.
Test True for group
These checkboxes let you specify which particles, if any, should become eligible for redirection to the next event upon satisfaction of the test conditions.
- Parent Particles
- When on, parent particles qualify for redirection when the test conditions are met. Default=on.
When using the Spawn on First Collision option, Parent Particles is available only when Delete Parent is off.
This option is also available when using the Spawn on Each Collision option. In this case, parent particles test True only after colliding the number of times specified by the Until # value.
- Spawn Particles
- When on, spawned particles qualify for redirection when the test conditions are met. Default=on.
Deflectors group
This group displays the deflectors currently in effect, and let you add and remove deflectors.
- [list]
- Shows the deflectors that apply to this operator. If more than three deflectors apply, a scroll bar appears at the right side of the list.
If you delete a listed space warp from the scene, its name is replaced in the list by the entry “<deleted>”.
- Add
- Click this button, and then select a Deflector space warp in the scene to add it to the list.
- By List
- Click this button, and then use the Select Deflectors dialog to add one or more space warps to the list. The space warps must already exist in the scene.
- Remove
- Highlight a deflector in the list, and then click this button to remove it from the list. Any removed space warps remain in the scene.
Spawn Rate And Amount group
Use these settings to specify when particles are to spawn and other values related to how many particles are spawned.
- Spawn On First Collision Particles spawn only the first time they collide with a deflector.
Delete Parent When on, deletes each original particle from which a new one is spawned. Available only with the Spawn On First Collision option.
- Spawn On Each Collision Particles spawn on each of multiple collisions, up to a limit specified with the Until # parameter.
Until # The maximum number of collisions by the parent particles that produce spawned particles. Available only with the Spawn On Each Collision option. Default=3.
When Test True For
Parent Particles is on, parent particles test True only after colliding the number of times specified by the Until # value.
- Spawnable
- The percentage of particles in the current event that will spawn new particles. This is determined once for each particle, when it enters the event. However, the parameter is animatable. Default=100.0.
For values other than 100.0, Spawnable uses a randomized selection process, which is affected by the Uniqueness Seed value. For example, with five parent particles, Offspring #=1, and Spawnable=80.0, you might get any number of spawned particles between two and five for each collision. The average per spawning would be four, however.
- Offspring #
- The number of new particles the system creates from each parent particle for each spawning event. Default=1.
- Variation
- The amount by which the Offspring # value can vary randomly. Default=0.0.
To obtain the actual test value for each particle, the system multiplies the Variation value by a random number between -1.0 and 1.0, and then applies the result as a percentage of the Offspring # setting. For example, if Offspring #=20 and Variation=10, then the actual number of offspring for each particle would be between 18 and 22.
- Sync By
- Choose the time frame to use when animating Offspring # and Variation:
- Absolute Time Any keys set for parameters are applied at the actual frames for which they're set.
- Particle Age Any keys set for parameters are applied at the corresponding frames of each particle's existence.
- Event Duration Any keys set for parameters are applied to each particle starting when it first enters the event.
- Restart Particle Age
- When on, sets the age of each newly spawned particle at 0. When off, each spawned particle inherits its parent's age. Default=on.
Speed group
Lets you specify the behavior of spawned particles, as well as their speed in absolute terms or relative to the parents' speed, with optional random variation. The direction of a spawned particle is always in relation to that of its parent, but you can set a Divergence so they eventually spread out. Default=Inherited.
- Parent
-
Specify the parent's behavior. Available only when Delete Parent is off.
- Bounce The speed and direction after collision is determined by the deflector properties.
- Continue Particle speed and direction are unaffected by the collision.
- Offspring
-
Specify the behavior of the newly spawned particles.
- Bounce The speed and direction of offspring after collision is determined by the deflector properties.
- Continue Speed and direction of offspring are unaffected by the collision.
- In Units Choose this to specify the speed of spawned particles in system units per second. Default=100.0.
A positive value inherits the parent's direction; a negative value reverses it.
- Inherited % Choose this to specify each spawned particle's speed as a percentage of its parent's speed. Default=100.0
A positive value inherits the parent's direction; a negative value reverses it.
- Variation %
-
The amount by which a spawned particle's speed can vary randomly. Default=0.0.
To obtain the actual speed for each spawned particle, the system multiplies the Variation value by a random number between -1.0 and 1.0, and then adds the result to the particle's speed as specified or inherited. For example, if a particle's speed is 100 units/second and Variation=20, then the tested value for each particle would be between 80 and 120 units/second.
- Divergence
-
When on, spreads out the stream of spawned particles. Use the numeric setting to define the extent of the divergence in degrees. Range=0 to 180. Default=12.0.
Size group
- Scale Factor %
- The amount of uniform scaling to apply to each spawned particle, as a percentage of its parent's size. Default=100.0.
- Variation %
- The amount by which a spawned particle's scale can vary randomly. Default=0.0.
To obtain the actual scaling for each spawned particle, the system multiplies the Variation value by a random number between -1.0 and 1.0, and then adds the result to the Scale Factor value. For example, if Scale Factor=100 and Variation=20, then each spawned particle would be between 80 and 120 percent of its parent's size.
Uniqueness group
The Uniqueness setting enables randomization of the Spawnable result, when less than 100.0, as well as of the Variation values.
- Seed
- Specifies a randomization value.
- New
- Calculates a new seed using a randomization formula.