OpenAL 3d Positioning and Panning Center

Question

Using OpenAL, one can set the distance model:

alDistanceModel(AL_LINEAR_DISTANCE_CLAMPED);

And the position of a sound effect:

float globalRefDistance = 125.0f;
float globalMaxDistance = 1250.0f;
ALfloat alPos[] = {pos.x, pos.y, 0.0f}; 
alSourcefv(soundId, AL_POSITION, alPos);
alSourcef(soundId, AL_REFERENCE_DISTANCE, globalRefDistance);
alSourcef(soundId, AL_MAX_DISTANCE, globalMaxDistance);

This attenuates and pans the sound nicely, except when the listener is close to the source and steps back and forth to the left and right of the sound. In this case, the panning quickly goes from left to right. There is not really a spot where it plays the sound panned in the center.

How can I define a range/window/cone where OpenAL puts a 3d sound right in the center, without panning?

I want to be able to walk up to the sound from the left, hearing it gradually fade in from the left channel. Then be in both channels for awhile. Then gradually fade out in the right channel.

I've tried messing with setting the sound to be directional, but it doesn't seem to do the trick:

alPos[0] = 0.0f; alPos[1] = 0.0f; alPos[2] = 1.0f;
alSourcefv(soundId, AL_DIRECTION, alPos);
alSourcef(soundId, AL_CONE_INNER_ANGLE, 180.0f);
alSourcef(soundId, AL_CONE_OUTER_ANGLE, 240.0f);

Answer 1

Instead of using OpenAL's AL_POSITION, I ended up tracking the listener position and all sound positions by hand, then manually applying volume rolloff and panning each tick.

This allows a certain window/width/cone of space where an effect is panned fully center. It sounds much better.

Also note that I switched from AL_LINEAR_DISTANCE_CLAMPED back to the default inverse clamped mode. For some reason the linear clamped mode was causing any effect that was positioned with a negative X value to pan much too quickly, regardless of reference or maximum distance. This only happened on Mac builds, so I think the OpenAL Mac implementation has a panning bug when using linear clamped.