A synthesizer allowing control of pitch, shape, frequency/amplitude modulation and low-pass filter by hand-drawing of waveforms.

A functional demo is available here: http://www.youtube.com/watch?v=qa8yd9GPcBU

The screen has three areas; waveform drawing area, control selection, utility functions.

In the waveform drawing area you can drag your finger to change or draw a new shape that affects the sounds playing.

Control selection has eight options that control the sound -
Red: Primary waveform.
Orange: Primary frequency (i.e. the main melody).
Yellow: Secondary waveform (used as amplitude or frequency modulation of the first waveform, or as a second oscillator).
Green: Secondary frequency.
Cyan: Envelope (i.e. the volume shape for the playing sound).
Blue: Envelope frequency.
Purple: Mixer control, between the playing sound and any running loop.
Magenta: Low-pass filter cutoff frequency.

Utility functions are eight options that control how the waveform is edited and looping -
Draw: When this option is selected the waveform changes instantly as you draw it.
Slide: When this option is selected the waveform will slide from its current value to what you draw.
Line: When this option is selected the waveform will change a horizontal line at the point selected. On the Primary waveform (Red) this option is not allowed.
Sine: When this is pressed the waveform will become more like a sine wave.
Overtone: When this is pressed a 2nd harmonic will be added.
Soften: When this is pressed any rough edges on the current waveform will be softened
Record: Pressing this will start a loop being recorded. If Record is pressed again after starting to record an echo of the time between presses will be created.
Play: If Record has been pressed then pressing Play after it will create a loop of what was playing between the presses. If a loop is already playing, pressing Play again will stop it.