sampler3D noiseMap : $noiseMap;

//FIXME: Use a different number of octaves based on the shader quality settings?


half bandLimitedNoise( float3 P ) {
	return tex3D( noiseMap, P ).x;
}

half perlin(float3 inpos) {
	half4 octaveScales = { 0.5, 0.25, 0.125, 0.0625 };
	half4 noiseSamples;

	//FIXME: use inpos+inpos? is add still faster than a mul?
	noiseSamples.x = bandLimitedNoise( inpos );
	noiseSamples.y = bandLimitedNoise( inpos*2 );
	noiseSamples.z = bandLimitedNoise( inpos*4 );
	noiseSamples.w = bandLimitedNoise( inpos*8 );

	return dot( noiseSamples, octaveScales );
}