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Using Ephemeral Property Mapper operators to adjust values (PB only)


    By default, Particle Playground replaces the value of a particle's property with the value represented by the layer map pixel at the particle's current location. You can also amplify, attenuate, or limit the resulting values by specifying a mathematical operator in the Ephemeral Property Mapper, and then using both the value of a particle's property and its corresponding layer map pixel value. Operators are available only in the Ephemeral Property Mapper. The following operators are available:

    Set

    Replaces the value of a particle property by the value of the corresponding layer map pixel. This is the default operator.

    Add

    Uses the sum of the value of a particle property and the value of the corresponding layer map pixel.

    Difference

    Uses the absolute value of the difference of the value of a particle property and the brightness value of the corresponding pixel on the layer map. Because it takes the absolute value of the difference, the resulting value is always positive. This operator is useful when you want to limit values to only positive values. If you're trying to model realistic behavior, the difference operator may not be ideal.

    Subtract

    Starts with the value of a particle property and subtracts the value of the brightness value of the corresponding pixel on the layer map.

    Multiply

    Multiplies the value of a particle property by the value of the brightness value of the corresponding pixel on the layer map and uses the result.

    Min

    Compares the brightness value of the layer map to the value of the particle property and uses the lower value.

    Max

    Compares the brightness value of the layer map to the value of the particle property and uses the higher value.

    If you are not familiar with mathematical operators, the following guidelines can help you decide whether you should use an operator:

    • The most predictable operator to use is Set, which is the default, because it simply replaces the value of a particle property with the value of the brightness value of the corresponding pixel on the layer map.
    • To amplify existing values of properties, try applying the Add operator with positive values or the Multiply operator with values above 1.0.
    • To attenuate (tone down) property value changes, try applying the Multiply operator using values between 0 and 1.0.
    • To limit a particle property so it is less than or equal to a value, use the Min operator and set both the Min and Max properties to that value. If you use a white solid as a layer map, you need only set the Max property to that value.