membraneCircle input tension loss
membraneHexagon input tension loss

Triangular waveguide meshes of a drum-like membrane.  Input is
an excitation signal, such as a pulse of noise.  Tension and
loss are k-rate.

The variants are named after the shape made out of triangular 
meshes.

Excite the mesh with some pink noise, triggered by an 
impulse generator.  mouseX is tension and impulse frequency, 
mouseY is duration of excitation, release-time and amplitude.

> let { x = mouseX KR 0 1 Linear 0.2
>     ; y = mouseY KR 1e-9 1 Exponential 0.2
>     ; loss = linLin y 0 1 0.999999 0.999
>     ; wobble = sinOsc KR 2 0
>     ; tension = linLin x 0 1 0.01 0.1 + (wobble * 0.0001)
>     ; p = envPerc 0.0001 y
>     ; tr = impulse KR (linLin x 0 1 3 9) 0
>     ; e = envGen KR tr (linLin y 0 1 0.05 0.25) 0 0.1 DoNothing p
>     ; m = membraneCircle }
> in do { n <- pinkNoise AR
>       ; audition (out (mce2 0 1) (m (n * e) tension loss)) }