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Boost Design Guidelines

The boost feature allows to increase the perceived intensity of haptic effects.

There are two layers of boost which are simply added together for each haptic effect:

  • The Global Boost which is applied to every effect being rendered as to increase them evenly. It can be set with setGlobalIntensityBoost() (depending on the API used) and is meant to be set by the user as an application setting.

  • The Effect Boost which is set for a single effect instance only. A default value can be set in Unitouch Studio and is saved in the .spn file as the reference value chosen during the design process. However, it can be overridden when triggering an effect with playEffect() (depending on the API used) by setting the boolean overridePatternBoost to true, in which case the effectBoost value passed is used instead of the default.

Since some effects are, by design, stronger than others, this two-layer feature is meant to allow the haptic effect designer to adjust the level intensity for each pattern of a set of patterns, while maintaining the design intent.

As they all have a default boost value in the .spn that is added to the global boost intensity, it can be set to compensate for the discrepancy of intensity across a set of patterns.

Weaker effects can have a high default boost value, while already strong effects can have a negative default boost value to reduce or even nullify the global intensity boost set by the user.

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Note that the overall boost can not decrease the effect's base intensity.

The boost increases the overall perceived intensity of the haptic effects. However, the higher the boost activation, the more the haptic effects are degraded. Although the “texture” of the effect is less affected, high levels of boost result in a loss of precision in the spatialization of the effect. Hence, setting the value of the boost is a matter of compromise between perceived intensity/power and deterioration of the effect’s signal and spatial resolution.

Keep in mind

Note that the boost is not impacted by the actuators’ activation levels but is modulated by the volume envelope defined in the pattern. This enforce the design process of:

  • Defining the spatialization: where the effect is being rendered.
  • Defining the volume envelope: how the intensity varies over the duration of the effect.
  • Defining the default boost value: the reference value with respect to the whole set of patterns that will be used altogether.