The Create Strands compound is the main one you need for creating strands. This compound creates continuous segments from a particle, like a strand or tail. You can use any particle shape for the strands.
If you use this compound, you cannot also use the Generate Strand Trails compound with the same particle emission in the ICE tree.
You can create stationary strands so that the particles and strands never leave the emitter, which is useful for creating effects such as hair, grass, or seaweed. To do this, you can set the particle’s Speed value to 0. If the Speed value is more than 0, the particles leave the emitter, but the strands stay tethered to the emitter.
Using the Constrain Strand Length or Align Strand on Particle Trajectory compound in conjunction with Create Strands, you can have the particles leave the emitter with their strands trailing behind them, which is good for creating moving particle effects such as ribbons, kite tails, streamers, tadpoles, or sperm!
To create particle strands
1. Create a particle emission—see Creating ICE Particle Emissions for information.
2. In the ICE tree’s preset manager, click the Task tab and select Particles.
3. Drag the Create Strands compound from the Strands group into the ICE view.
4. Plug this compound’s Execute on Emit output into an Execute on Emit port on an Emit compound.
You can also plug it into any Execute port of a State compound, if you’re using a state system.
5. In the Emit compound, select the Shape type you want to use for the strand. This shape is repeated along the strand’s length (one shape per segment). All shape types are supported. You can see the results in the render region — here are a few of them:
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The Segment shape renders particles as strands by drawing a constant line along the length of the strand.
6. If you want the particles and their strands to stay on the emitter, set the Speed value in the Emit compound to 0 (zero). This way, the strands flow away from the emitter but always stay attached to it.
- If you want the particles to move away from the emitter, set the Speed value to anything other than 0. However, the strands stay tethered to the emitter.
- If you want the particles to move away from the emitter with the strands following them, you need to add the Constrain Strand Length compound (see Keeping Strands the Same Length) or the Align Strand on Particle Trajectory compound (see Aligning Strands Along the Particle Trajectory).
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Try plugging the Turbulize Particle Velocity compound into the ICETree node to create a more natural movement for the strands. |
7. In the Create Strands property editor, you can set the strand length and number of segments, loft the particle shape along the strand (create a solid-looking strand), set the strand size and shape using a profile curve, and set the strand color using a gradient.
For more information on the parameters, click the ? icon in the property editor or see Create Strands.
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The color gradient is displayed in the render region only if you have an appropriate color gradient shader set up for the particles in the render tree, such as the Particle Density shader or the Particle Strand Gradient shader compound—see Particle Density (ICE) [Particle Shaders]. |
Keeping Strands the Same Length
The Constrain Strand Length compound makes the strands follow particles like trails. If the particles leave the emitter, the strands follow behind like strings that always keep the same length. This compound is also useful for creating hair if you’re using particles that have no emission speed.
The strands don’t follow the particle’s path exactly as they do with the Align Strand with Particle Trajectory compound.
To make strands keep the same length
1. Create strands using the Create Strands compound from the Strands group, as described in the previous section, Creating Strands.
You can have the emission Speed set to 0 to keep the particles and their strands on the emitter, or set it above 0 to have the particles and their strands move away from the emitter.
2. Drag the Constrain Strand Length compound from the Strands group into the ICE view.
3. Plug its Execute output into a Port on the ICETree node.
4. Initially, strands are emitted before the particles, then the particles move along those strands as they leave the emitter. To have the particles leave the emitter and the strands follow directly, set the Strand Length value in the Create Strand property editor to a very small value.
Aligning Strands Along the Particle Trajectory
The Align Strand to Particle Trajectory compound makes the strands follow exactly along the particles’ paths (trajectory). This is useful for creating ribbons, party streamers, or snakes whose trajectory is varied and dynamic. Unlike the Constrain Strand Length compound that always keeps the strands the same length regardless of movement, these strands may “stretch” a bit in order to follow the particle path.
To make strands follow particles along their paths
1. Create strands using the Create Strands compound from the Strands group, as described in the previous section, Creating Strands.
You can have the emission Speed set to 0 to keep the particles and their strands on the emitter, or set it above 0 to have the particles and their strands move away from the emitter.
2. Drag the Align Strand to Particle Trajectory compound from the Strands group into the ICE view.
3. Plug its Execute output into a Port on the ICETree node.
In the tree shown below, the Strand Sin Wave Movement has been added to create an undulating wave effect on the strands.
4. Initially, strands are emitted before the particles, then the particles move along those strands as they leave the emitter. To have the particles leave the emitter and the strands follow directly, set the Strand Length value in the Create Strand property editor to a very small value.
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