uniform sampler2D NotesData;

uniform float     OverallSoundPosition;
uniform float     ThisSoundLength;

#define NOTES 36
#define BASEFREQ 40.

#define FREQ 150.

float saw(float time)
{
	//works in the same time domain as GLSL sine
	float x = mod(time, 6.28318531) / 3.14159265;
	return x - 1.;
}

float triangle(float time)
{
	//works in the same time domain as GLSL sine
	float x = mod(time, 6.28318531) / 3.14159265;
	float f = floor(x);
	x = (x*(1.-f)) + ((2.-x)*f);
	return (x*2.)-1.;
}

void main()
{
	int i;
	float fvol = 0.;

	float TimeSample = gl_TexCoord[0].y * ThisSoundLength + OverallSoundPosition;
	float channel = gl_TexCoord[0].x;

	//this is a bad way to add voices together. it gets very loud!!!!
	for( i = 0; i < NOTES; i++ )
	{
		float noteA = texture2D( NotesData, vec2( i/NOTES, 0.0 ) ).r;
		float noteB = texture2D( NotesData, vec2( i/NOTES, 0.5 ) ).r;

		float freq = pow( 2., float(i)/12. ) * BASEFREQ;

		fvol += sin( freq * TimeSample );
	}


	//frequency modulation
	
	float fcar = 6.28318531 * FREQ * TimeSample;
	float fmod = 6.28318531 * FREQ * 1.5 * TimeSample;
	
	fvol = 1. * sin(fcar + 2.2449 *sin(fmod));
	gl_FragColor = vec4( fvol );
}