You can set the color of the particles for display in the viewport. Rendered particles will not use these particle color values unless you have set up the shaders in the render tree to do so (see Using the ICE Particle Color in the Render Tree). For information on particle shaders in general, see ICE Particle Shading.
You can modify the particle color in different ways, such as by using a simple gradient or by randomizing and turbulizing the particle color values.
You can also use the colors from texture map images or vertex color maps to set the color of the particle.
There are also many nodes in the Color group on the Tool tab that you can use, such as different types of color converters.
You can set the color of the particles at the time that they’re emitted.
To set the initial particle color
1. Create a particle emission—see Creating ICE Particle Emissions.
2. Open an Emit compound’s property editor and set the Color using the standard color sliders.
For more information about using these color tools, see Defining Color Properties [ Interface and Tools ].
Modifying the Particle Color Over Time (Color Shift)
To have a particle change color over its lifetime using a gradient, you can use the Modify Particle Color compound. This compound modifies specific aspects of the particle color (such as separate RGB or HLS components) based on different methods.
This makes it easy to create a color shift based on different factors such as the particle’s age or age percentage, or the length of the simulation.
You can modify the particle color at emission or the current color.
To change the particle color over time
1. Create a particle emission—see Creating ICE Particle Emissions.
2. Click the Task > Particles tab in the preset manager on the left side of the ICE Tree.
3. Select the Modify Particle Color compound from the Modifiers group, and drag it into the graph area.
4. Plug this compound’s Execute output into a Port on the ICETree node.
You can also plug its Execute output into any Execute port of other compounds such as Slide on Surface, Bounce on Surface, or Stick to Surface. For example, you can change the particle color as it slides on a surface.
5. Open the Modify Particle Color property editor and set the properties. The gradient gives you control over how the particle color changes over time.
If you use Age Percentage as the Source Parameter, you must first define the particle’s age limit using the Set Particle Age Limit compound (see ICE Particle Lifespan).
For more information on the parameters, click the ? icon in the property editor or see Modify Particle Color.
Randomizing and Turbulizing the Color
There are several compounds on the Task > Particle tab that let you add randomness or turbulence (noise) to the Color value so that the particles are not all emitted using the same color. Adding randomness or noise helps the particles look more natural for certain types of effects.
The Randomize Color compound adds a random value to all or just specific channels of the particle color so that each particle is emitted using a range of different colors. You set a mean value around which you determine the range of variance of color values.
To randomize the particle color
1. Create a particle emission—see Creating ICE Particle Emissions.
2. Click the Task > Particles tab in the preset manager on the left side of the ICE Tree.
3. Select the Randomize Color compound from the Modifiers group, and drag it into the graph area.
4. Plug this compound’s Random Color output into any Color port, such as the one of the Emit compound.
5. Open the Random Color property editor and set the properties. You can set the color channel you want to randomize (RGB, Red, Green, Blue, Hue, Lightness Saturation, or Alpha), a Seed value, and a Mean Value around which you determine the Variance of color values.
For more information on the parameters, click the ? icon in the property editor or see Randomize Color.
Randomizing the Color Using a Gradient
The Randomize Color Using Gradient compound uses a gradient to randomly distribute the colors to the particle at emission.
To randomize the particle color using a gradient
1. Create a particle emission—see Creating ICE Particle Emissions.
2. Click the Task > Particles tab in the preset manager on the left side of the ICE Tree.
3. Select the Randomize Color Using Gradient compound from the Modifiers group, and drag it into the graph area.
4. Plug this compound’s Out output into any Color port, such as the one on the Emit compound.
5. Open the Random Color Using Gradient property editor and set the colors in the gradient. The particle color is taken from this gradient randomly at emission time.
For information on using gradient controls in general, see Particle Gradient Shader.
Turbulizing the Color Using a Gradient
The Turbulize Color by Gradient compound uses a gradient to add turbulence (noise) to the particle color at emission.
To turbulize the particle color using a gradient
1. Create a particle emission—see Creating ICE Particle Emissions.
2. Click the Task > Particles tab in the preset manager on the left side of the ICE Tree.
3. Select the Turbulize Color by Gradient compound from the Modifiers group, and drag it into the graph area.
4. Plug this compound’s Out output into any Color port, such as the one on the Emit compound.
5. Open the Turbulize Color by Gradient property editor and set the colors in the gradient. The particle color is taken from this gradient at emission time depending on the turbulence scale, animation speed, and complexity (fractal-type) values that you set.
For more information on the parameters, click the ? icon in the property editor or see Turbulize Color by Gradient.
For information on using gradient controls in general, see Particle Gradient Shader.
Using a Texture Map to Set the Particle Color
You can create a texture map on different objects and use it to define the particle color using the Get Texture Map Color compound. The objects you can use are based on different locations you can choose. This can be the emitter object, an obstacle for collisions, sticking, or sliding, a goal object, or just any object you use as an input.
Texture maps consist of an image file or sequence and a set of UV coordinates. They are similar to ordinary textures, but are used to control parameters instead of surface colors. To create a texture map, you select a texture projection method and then link an image file to it, all in the texture map property.
The Get Texture Map Color compound then takes the color values from the image defined for the texture map and uses them to change the color of the particles.
To set the particle color using a texture map
1. Select the object to which you want to apply a texture map and choose Get > Property > Texture Map from any toolbar. A texture map is applied and its property editor opens.
This object can be the emitter object, an obstacle for collisions, sticking, or sliding, a goal object, or just any object you use as an input.
2. Select the texture projection method according to the object’s geometry and then select an image or sequence to link to it. The texture projection maps the colors of the image to the geometry.
For more information in general on texture maps, see Texture Maps.
3. Create a particle emission—see Creating ICE Particle Emissions.
4. Make sure that the object whose texture map you want to use is in the ICE tree and connected (such as the emitter object being connected to the Emit compound).
5. Click the Task > Particles tab in the preset manager on the left side of the ICE Tree.
6. Select the Get Texture Map Color compound from the Getters group and drag it into the graph area.
7. Plug this compound’s output into a Color port of any compound to which the object with the texture map is connected, such as the one on the Emit compound.
8. In the Get Texture Map Color compound’s property editor, select the type of Location you want to use for the texture map colors according to the object that has the texture map: Emit, Collide, Stick, Slide, Goal, or Input. This is based on the object that’s got a texture map defined and is plugged into the ICE tree.
9. Then use the Explorer button to select the texture map on the object that you want to use.
Using Vertex Colors to Set the Particle Color
Vertex color properties, also known as color at vertices properties or CAVs, are colors stored in the polynodes (subvertices) of an object. They can be used for a variety of purposes, such as storing surface color, illumination, or custom data.
You can create a vertex color map on an object and then use its color values to define the particle color using the Get Vertex Color Value compound. The objects you can use are based on different locations you can choose. This can be the emitter object, an obstacle for collisions, sticking, or sliding, a goal object, or just any object that you use as an input.
For more information on vertex colors in general, see Vertex Colors [Texturing].
To set the particle color using a vertex color map
1. Select the object to which you want to apply a vertex color map and choose Get > Property > Color at Vertices Map from any toolbar. A vertex color map is applied to the object (under its Clusters > UV_Cluster node) and its property editor opens.
This object can be the emitter object, an obstacle for collisions, sticking, or sliding, a goal object, or just any object you use as an input.
2. Paint on the map by pressing Shift+W (press Ctrl+W to open the Brush property editor).
3. Create a particle emission—see Creating ICE Particle Emissions.
4. Make sure that the object whose vertex color map you want to use is in the ICE tree and connected (such as the emitter object being connected to the Emit compound).
5. Click the Task > Particles tab in the preset manager on the left side of the ICE Tree.
6. Select the Get Vertex Color Value compound from the Getters group and drag it into the graph area.
7. Plug this compound’s output into a Color port of any compound to which the object with the vertex color map is connected, such as the one on the Emit compound.
8. Plug the Value output from the object with the vertex color map into the Geometry port of the Get Vertex Color Value compound.
9. In the Get Vertex Color Value compound’s property editor, enter the object’s vertex color map name and Colors attribute in the reference text box or click the Explorer button to select a vertex color map to use.
The syntax should be like this, substituting the correct vertex color map name: .cls.UV_Cluster_AUTO.Vertex_Color.Colors
10. You can specify the Cutoff Distance, which is the maximum distance (in Softimage units) from a vertex that a particle can be in order to take on its color. For example, if you only want particles to change color when they come within 1 unit of a goal object, set this value to 1.
11. Select a Proximity Method, which is the geometry component of the object that is used to calculate the cutoff distance for the particle: Closest Surface, Closest Vertex or Knot, or Closest Smoothed Surface.
There are two particle attributes that are used to define particle color. These attributes are used in several compounds, but you can also use them on their own in an ICE tree by specifying them in the Get Data and Set Data nodes, as described in Using ICE Particle Attributes.
For more information on attributes in general and a list of all available ICE attributes, see ICE Attributes.
• Init_Color: A particle’s original Color value when it is emitted. This attribute it set by the Emit compounds, but you can change its value using the Color sliders in the Emit property editor (see Setting the Initial Color).
You can also set this attribute in the Modify Particle Color compound by selecting the Modify Emit Color option for the Modification Base parameter.
• Color: The color of particles in the viewport. By default, this color is not used for rendering unless you get the Color attribute into the point cloud’s render tree using an Attribute Color shader (see Using the ICE Particle Color in the Render Tree below).
The Color attribute is used in a number of compounds, including Modify Particle Color, Randomize Color, Randomize Color Using Gradient, Turbulize Color by Gradient, and Get Vertex Color Value, all described in this section.
You can also get and set the Color attribute with the Get Particle Color and Set Particle Color compounds, which are simply the Get Data and Set Data nodes with the Color attribute already specified.
Using the ICE Particle Color in the Render Tree
When you set the particle color in the ICE tree, it’s used only for their display in the viewports. However, you may want to use this color for rendering the particles, especially if you want to override the color of instanced geometry. This is easy to do by using the Attribute Color shader.
For more information about the attribute shaders, see Bringing ICE Data into the Render Tree with Attribute Shaders.
To use the ICE particle color in the render tree
1. Set up a particle system in the ICE tree as you like.
2. Set the particle color in the ICE tree using any of the compounds or nodes that set the Init_Color or Color attribute (see Particle Color Attributes above).
In the case of particle instanced geometry, the geometry’s color is used when rendered.
3. Open the render tree and drag the Color shader from the Attributes group in the preset manager into the render tree workspace.
4. Open the Attribute_Color property editor and select Color or Init_Color as the Attribute to use in the shader (depending on which compound you’re using to set the color; for example, the Emit compounds set the Init_Color attribute).
5. Connect the Attribute_Color shader’s output to any color input port (such as the Diffuse port) on a shader that’s connected to the point cloud’s Material node.
6. Draw a render region and see that the particle color attribute is now used for the particle’s render color.
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