BASS_Set3DFactors

Sets the factors that affect the calculations of 3D sound.

BOOL BASS_Set3DFactors(
    float distf,
    float rollf,
    float doppf
);

Parameters

distf	The distance factor... 0 or less = leave current... examples: 1.0 = use meters, 0.9144 = use yards, 0.3048 = use feet. By default BASS measures distances in meters, you can change this setting if you are using a different unit of measurement.
rollf	The rolloff factor, how fast the sound quietens with distance... 0.0 (min) - 10.0 (max), less than 0.0 = leave current... examples: 0.0 = no rolloff, 1.0 = real world, 2.0 = 2x real.
doppf	The doppler factor... 0.0 (min) - 10.0 (max), less than 0.0 = leave current... examples: 0.0 = no doppler, 1.0 = real world, 2.0 = 2x real. The doppler effect is the way a sound appears to change pitch when it is moving towards or away from you. The listener and sound velocity settings are used to calculate this effect, this doppf value can be used to lessen or exaggerate the effect.

If successful, then TRUE is returned, else FALSE is returned. Use BASS_ErrorGetCode to get the error code.

BASS_ERROR_INIT	BASS_Init has not been successfully called.
BASS_ERROR_NO3D	The device was not initialized with 3D support.

As with all 3D functions, use BASS_Apply3D to apply the changes.

When using multiple devices, the current thread's device setting (as set with BASS_SetDevice) determines which device this function call applies to.

Use yards as the distance measurement unit, while leaving the current rolloff and doppler factors untouched.

BASS_Set3DFactors(0.9144, -1.0, -1.0);
BASS_Apply3D(); // apply the change