Particle group > Texture group
The Texture group lets you select a layer to be the custom particle texture. It also sets the particle texture's behavior, for instance, which frame of the layer to sample from. The particles that use particle textures are the Sprite and Textured Polygon options in the Particle Type popup. All layers or pre-composed layers are valid inputs. You can use a bitmap image, shape layer, movie or pre-comp. If you are using a text layer, that layer must be pre-comped.
Version 1.5 Note: The Texture group used to be called Custom Layer. Its parameters work much the same as they did before, with some interesting additions.
At left, the full Texture group parameters. In middle, the three Sprite options in Particle Type. At right, the three Textured Polygon types.
Layer
This chooses the source layer that will be used as a 'texture' or custom particle. All other Texture group parameters affect the image loaded into Layer.
By default, the Layer popup is set to None and turned off. To turn it on, just choose a layer from the popup box. This layer has to be in your Timeline, and the View (eye icon) should be turned off for that layer.
At left, the Layer popup shows all available layers. At right, those layers are present but turned off in the Timeline.
Here is an example of Layer applying a custom particle.
At left, a 'Crescent' bitmap image. In middle, the Crescent layer loaded into the Layer popup. At right, the composition with Crescents used as custom particles.
If you try to apply a layer that is really large, like comp-sized, a warning message will appear. This warming will tell you to use a smaller layer.
Time Sampling
Time Sampling determines which frame of the layer is sampled to generate the custom particle. There are 11 modes. The mode determines which frame the custom particle is sampled from with options for starting from the first frame, picking a random frame, or splitting the layer source into multiple clips.
The default choice is Current Time. If the custom particle is a still image, the mode should always be set to Current Time. This option will speed up rendering because the same frame of the layer is used for all particles in the current frame.
When using an animated particle, the other modes are useful. The Start, Random and Split modes can drastically reduce the time needed to pre-render the custom particle layer. Following is an explanation of how each works.
The Start modes all begin at frame one (the 'start') of the custom input layer.
Start at Birth - Play Once: Plays the custom layer from start once. The particle may die before the custom layer ends, or the custom layer may end before the particle dies.
Start at Birth - Loop: Plays the custom layer from start and restarts (or loops) if the layer ends.
Start at Birth - Stretch: Plays the custom layer from start and time-stretches it so it ends exactly when the particle dies.
The Random modes pick a frame at random to use.
Random - Still Frame: Selects a random frame from the custom layer and uses it throughout the particle's life.
Random - Play Once: Starts playing the custom layer from a random frame, and then plays at normal speed. The particle may die before the custom layer ends, or the custom layer may end before the particle dies.
Random - Loop: Starts playing the custom layer from a random frame, and then plays at normal speed. If the custom layer ends, it loops and restarts from the beginning.
Split Clip modes split the custom layer into a number of clips. The number is set the parameter Number of Clips. For example, if the custom layer is 30 frames and Number of Clips is set to 3, that means the custom layer will be split into three 10 frame clips. This is useful for creating a set of animated particles. Split Clip - Play Once: Randomly selects one of the clips and play the clip once. Split Clip - Loop: Randomly selects one of the clips and play the clip looping. Split Clip - Stretch: Randomly selects one of the clips and time-stretch it to fit the particle life.
There is a new option called Current Frame Freeze.
Current Frame Freeze: Holds the referenced particle image at the current time throughout the particles life. So any particles born at a certain frame will have that same appearance throughout the particle's life, even though the input layer may be animating. This happens at each frame.\
Random Seed (new to version 2.0)
Active when any of the Random Time modes are chosen in the Time Sampling popup. Random Seed randomizes which frame it is sampling from without changing the positions of the particles.
Number of Clips
Active when any of the Split Clip modes are chosen in the Time Sampling popup. Defines the number of clips in the custom layer that Split Clip uses.
For example, you may have 5 movies that are 10 frames each in a pre-comp. You may then select a Split Clip mode and set Number of Clips to 5. This will tell Particular to use just one of the 5 clips as the custom particle.
Subframe Sampling
Active when any of the Play Once, Stretch or Still Frame modes are chosen in the Time Sampling popup. This allows subframe sampling for the custom particle layer. This is useless if the custom particle is a movie, but if it is an animation, the plug-in can retrieve frames that are in-between frames.