spread - illustrates slab3d's spherical spread rolloff model.
spread( radiusBegin, radiusInc, radiusEnd, distBegin, distInc, distEnd,
srcSpread )
radiusBegin, radiusInc, radiusEnd - source radius (meters)
distBegin, distInc, distEnd - source-listener distance (meters)
srcSpread - spread exponent
spread displays rolloff curves and a gain table for a range of source
radii. slab3d's spherical spread rolloff model approximates a planar baffled
cylindrical piston with spread gain calculated as follows:
spread_gain = (1 + (distance / radius)^2) ^ (-srcSpread / 2)
The srcSpread parameter affects the rate at which the spread gain decreases as
the source-listener distance increases. The default value is 1.0. To exaggerate
spherical spreading, a higher value can be used. To disable spread rolloff,
a value of 0.0 should be used.
A dotted reference line is provided for the inverse distance law:
spread_gain = interaural_radius / distance
interaural_radius = 0.0889 meters
If the source radius and the interaural radius are set to identical values,
the two models are nearly identical (for interaural radius << distance).
Defaults: spread( 0.05, 0.2, 1.05, 0.1, 0.1, 4.0, 1.0 )