// Copyright (C) 2015 Rémi Bèges
// This file is part of the "Nazara Engine - Noise module"
// For conditions of distribution and use, see copyright notice in Config.hpp

#include <Nazara/Core/Error.hpp>
#include <Nazara/Noise/Config.hpp>
#include <Nazara/Noise/Perlin2D.hpp>
#include <Nazara/Noise/Debug.hpp>

NzPerlin2D::NzPerlin2D()
{
	float grad2Temp[][2] = {
		{1.f,1.f},
		{-1.f,1.f},
		{1.f,-1.f},
		{-1.f,-1.f},

		{1.f,0.f},
		{-1.f,0.f},
		{0.f,1.f},
		{0.f,-1.f}
	};

	for(int i(0) ; i < 8 ; ++i)
		for(int j(0) ; j < 2 ; ++j)
			gradient2[i][j] = grad2Temp[i][j];
}

NzPerlin2D::NzPerlin2D(unsigned int seed) : NzPerlin2D()
{
	this->SetNewSeed(seed);
	this->ShufflePermutationTable();
}

float NzPerlin2D::GetValue(float x, float y, float resolution)
{
	x *= resolution;
	y *= resolution;

	x0 = fastfloor(x);
	y0 = fastfloor(y);

	ii = x0 & 255;
	jj = y0 & 255;

	gi0 = perm[ii +	 perm[jj]] & 7;
	gi1 = perm[ii + 1 + perm[jj]] & 7;
	gi2 = perm[ii +	 perm[jj + 1]] & 7;
	gi3 = perm[ii + 1 + perm[jj + 1]] & 7;

	temp.x = x-x0;
	temp.y = y-y0;

	Cx = temp.x * temp.x * temp.x * (temp.x * (temp.x * 6 - 15) + 10);
	Cy = temp.y * temp.y * temp.y * (temp.y * (temp.y * 6 - 15) + 10);

	s = gradient2[gi0][0]*temp.x + gradient2[gi0][1]*temp.y;

	temp.x = x-(x0+1);
	t = gradient2[gi1][0]*temp.x + gradient2[gi1][1]*temp.y;

	temp.y = y-(y0+1);
	v = gradient2[gi3][0]*temp.x + gradient2[gi3][1]*temp.y;

	temp.x = x-x0;
	u = gradient2[gi2][0]*temp.x + gradient2[gi2][1]*temp.y;

	Li1 = s + Cx*(t-s);
	Li2 = u + Cx*(v-u);

	return Li1 + Cy*(Li2-Li1);
}