DemoGL::Reference::Functions::DEMOGL_SoundSystemSetListener3DPosition

DEMOGL_SoundSystemSetListener3DPosition

DEMOGL_SoundSystemSetListener3DPosition sets the position of the global listener, i.e. the user watching the application, in 3D space, inclusive its orientation. This way, the sound logic can calculate how the active sound channels will be heared by the 'user' at the global listeners position. There is one global listener position defined for all active channels. You can't have multiple listeners for different 3D setups in different effects running at the same time. 

int
DEMOGL_SoundSystemSetListener3DPosition(
	SListener3DPosition * const p3DPosition
);
Parameters.
p3DPosition
Pointer to filled SListener3DPosition structure with the 3D position, orientation and velocity to apply to the 3D position of the listener, i.e. the camera.

Return values.
If the function succeeds, it returns SYS_OK.
If the function fails, it returns SYS_NOK.

Remarks.
The position of the global listener is important for the sound logic to calculate the actually sound behaviour of all the active channels when those sounds arrive at the spot where the global listener is, if these channels are playing sound from elements which are loaded with 3D enabled. Channels playing sound data that is owned by elements which are loaded with 3D disabled, are not affected by the position of the global listener. When you want to make a moving global listener, and let the sound logic be able to update the current position to make the sounds appear correctly you should call DEMOGL_SoundSystemSetListener3DPosition each frame, but only once per frame, not from each running effect, because there is just one global listener.

NOTE: There is just one  listener position in the sound system, because that's the way the underlying sound library works. This way, you have to keep in mind that two or more effects visible at the same time with total different scenes have to use the same global listener position for their 3D enabled sound channels. It will be odd at first, but it's the same way OpenGL works: there is no camera, the frustum is always at (0,0,0) looking at the negative Z, the world is moved/rotated so it looks as if the 'camera' is rotated/moved. Updating the global listener position in more than one effect in one frame is useless: only the last one will have any effect.

Example.

Requirements.
DemoGL v1.3 (build 0112 or higher)

See also.
SListener3DPosition

Last changed on 18-jan-2001

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