Particles Shader

Overview

The Particles Shader is used by FX artists to create particle materials.

Shader Params

It consists of the following parameters:

Parameter	Description
Color Lookup Amplitude	Sets the color lookup brightness and multiplier. This parameter requires that Color Lookup is enabled in the Shader Generation Parameter is enabled.
Color Lookup Color Phase	Sets the per-color phase to be used. This parameter requires that Color Lookup is enabled in the Shader Generation Parameters is enabled.
Deform Amount	Controls deformation multiplier. This parameter requires that Deformation is enabled in the Shader Generation Parameters.
Deform Anim Speed	Controls deformation animation translation speed and frequency. This parameter requires that Deformation is enabled in the Shader Generation Parameters.
Deform Tiling	Controls deformation tiling. This parameter requires that Deformation is enabled in the Shader Generation Parameters.
Global Illumination Amount	Sets the amount of global illumination.
Perturbation Amount	Controls the amount of deformation that is used. This parameter requires that Screen Space is enabled in the Shader Generation Parameters.
Perturbation Anim Speed	Controls animation translation speed and frequency that is applied to the deformation map. This parameter requires that Screen Space is enabled in the Shader Generation Parameters.
Perturbation Tiling	Controls the tiling amount of deformation. This parameter requires that Screen Space is enabled in the Shader Generation Parameters.
Refraction Bump Scale	Sets the refraction bump scale. This parameter requires that Refraction is enabled in the Shader Generation Parameters.
Threshold for Writing Depth	Sets the threshold for writing depth. This parameter requires that Depth Fixup is enabled in the Shader Generation Parameters.

Shader Generation Params

The Particle Shader comprises of the following Shader Generation Parameters:

Refraction

Refraction enables particle refraction, which is useful to simulate heat haze coming from fire or any heat source or for some specific visual effect look. This increases the rendering cost slightly, so it should be used sparingly. When the refraction option is used, users should ensure that they are using a normal map also for deformation.

Shader Param	Description
Refraction Bump Scale	When the Refraction option is enabled, users can use this scale for controlling the amount of deformation on refractions.

Screen Space Deformation

Screen Space Deformation (SSD) deforms particles in screen space (screen aligned deformation). When Screen Space Deformation is used, set the normal map to be used as deformation map in the Custom slot.

Shader Param	Description
Perturbation Anim Speed	This parameter is used for SSD, it controls animation translation speed/frequency applied to the deformation map.
Perturbation Tilling	Another parameter used for SSD, for controlling the tilling amount of deformation.
Perturbation Amount	Used for SSD, this multiplier controls the amount of deformation used.

Deformation

Deformation, unlike SSD, where deformation is done screen aligned, this type of deformation is done in the particle UV space. When deformation option is used, set normal map to be used as deformation map in the Custom slot.

Shader Param	Description
Deform Tilling	Controls deformation tilling.
Deform Amount	Controls deformation multiplier.
Deform Anim Speed	Controls deformation animation translation speed/frequency.

Color Lookup

Color Lookup allows users to use a color lookup texture to have color gradient variation for the same particle effect. This is useful in particular to save video memory as users can, for example, have a grayscale diffuse map and use color lookup texture to get colors. When a color lookup is used, set the lookup gradient texture in the Custom Slot 1.

Shader Param	Description
Color Lookup Amplitude	Sets color look up amplitude/multiplier (how bright it will look).
Color Lookup Color Phase	sets the per-pixel (therefore per-color) phase to be used. Users can use this parameter to set a different range of colors coming from the gradient texture lookup.