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Perlin.cpp
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Perlin.cpp
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//
// Created by user on 2/28/2021.
//
/* Start Header -------------------------------------------------------
* Copyright (C) 2020 DigiPen Institute of Technology.
* Reproduction or disclosure of this file or its contents without the prior
* written consent of DigiPen Institute of Technology is prohibited.
* File Name: Perlin.cpp
* Purpose: Lorem ipsum dolor sit amet, consectetur adipiscing elit.
* Language: C++, G++
* Platform: g++ (Ubuntu 9.3.0-10ubuntu2) 9.3, ThinkPad T430u, Nvidia GT 620M,
* OpenGL version string: 4.6.0 NVIDIA 390.138
* Project: Eye
* Author: Roland Shum, roland.shum@digipen.edu
* Creation date: 2/28/2021
* End Header --------------------------------------------------------*/
#include "stdafx.h"
#include "Perlin.h"
Perlin::Perlin() {
ranvec = new vec3[point_count];
ranfloat = new double[point_count];
for(int i = 0; i < point_count; ++i)
{
ranvec[i] = glm::normalize(randomVec3(-1, 1));
ranfloat[i] = randomDouble();
}
perm_x = PerlineGeneratePerm();
perm_y = PerlineGeneratePerm();
perm_z = PerlineGeneratePerm();
}
Perlin::~Perlin() {
delete[] ranfloat;
delete[] perm_x;
delete[] perm_y;
delete[] perm_z;
delete[] ranvec;
}
double Perlin::Noise(const vec3 &p) const {
auto u = p.x - floor(p.x);
auto v = p.y - floor(p.y);
auto w = p.z - floor(p.z);
auto i = static_cast<int>(floor(p.x));
auto j = static_cast<int>(floor(p.y));
auto k = static_cast<int>(floor(p.z));
vec3 c[2][2][2];
for(int di = 0; di < 2; di++)
{
for(int dj = 0; dj < 2; dj++)
{
for(int dk = 0; dk < 2; dk++)
{
c[di][dj][dk] = ranvec[
perm_x[ (i + di) & 255] ^
perm_y[ (j + dj) & 255] ^
perm_z[ (k + dk) & 255]
];
}
}
}
return PerlinInterpolate(c, u, v, w);
}
int *Perlin::PerlineGeneratePerm() {
// We can prob use std::generator here
auto p = new int[point_count];
for (int i = 0; i < Perlin::point_count; i++)
p[i] = i;
Permute(p, point_count);
return p;
}
void Perlin::Permute(int *p, int n) {
for (int i = n-1; i > 0; i--) {
int target = randomInt(0, i);
std::swap(p[i], p[target]);
}
}
double Perlin::TrilinearInterpolate(double (*c)[2][2], double u, double v, double w) {
auto accum = 0.0;
for (int i = 0; i < 2; i++)
for (int j = 0; j < 2; j++)
for (int k = 0; k < 2; k++)
accum += (i * u + (1 - i) * (1 - u)) *
(j * v + (1 - j) * (1 - v)) *
(k * w + (1 - k) * (1 - w)) * c[i][j][k];
return accum;
}
double Perlin::PerlinInterpolate(vec3 (*c)[2][2], double u, double v, double w) {
// Hermite cubic
auto uu = u * u * (3 - 2 * u);
auto vv = v * v * (3 - 2 * v);
auto ww = w * w * (3 - 2 * w);
auto accum = 0.0;
for (int i = 0; i < 2; i++)
for (int j = 0; j < 2; j++)
for (int k = 0; k < 2; k++) {
vec3 weight_v(u - i, v - j, w - k);
accum += (i * uu + (1 - i) * (1 - uu))
* (j * vv + (1 - j) * (1 - vv))
* (k * ww + (1 - k) * (1 - ww))
* dot(c[i][j][k], weight_v);
}
return accum;
}
double Perlin::Turbulance(const vec3 &p, int depth) const {
auto accum = 0.0;
auto temp_p = p;
auto weight = 1.0;
for(int i = 0; i < depth; ++i)
{
accum += weight * Noise(temp_p);
weight *= 0.5;
temp_p *= 2;
}
return fabs(accum);
}