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TerrainGenerator.cpp
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#include "TerrainGenerator.h"
#include <algorithm>
// Permutation table
int TerrainGenerator::p[] = {151,160,137,91,90,15,
131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
190, 6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
88,237,149,56,87,174,20,125,136,171,168, 68,175,74,165,71,134,139,48,27,166,
77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208, 89,18,169,200,196,
135,130,116,188,159,86,164,100,109,198,173,186, 3,64,52,217,226,250,124,123,
5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
223,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167, 43,172,9,
129,22,39,253, 19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
251,34,242,193,238,210,144,12,191,179,162,241, 81,51,145,235,249,14,239,107,
49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127, 4,150,254,
138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180};
// 10 unit vectors
double TerrainGenerator::grad2[10][2] = {
{1.0, 0.0},
{0.81, 0.59},
{0.31, 0.95},
{-0.31, 0.95},
{-0.81, 0.59},
{-1.0, 0.0},
{-0.81, -0.59},
{-0.31, -0.95},
{0.31, -0.95},
{0.81, -0.59},
};
TerrainGenerator::TerrainGenerator()
{
}
TerrainGenerator::~TerrainGenerator(void)
{
}
// Defining grid of 64 units
double TerrainGenerator::getHeightValue(int x, int y)
{
double tx, ty;
tx = float(x)/GENERATOR_GRID_SIZE;
ty = float(y)/GENERATOR_GRID_SIZE;
double total = 0.0;
double frequency = this->frequency;
double amplitude = this->amplitude;
return getValue(tx, ty);
}
double TerrainGenerator::getValue(double x, double y)
{
double rx, ry;
int ix, iy;
ix = fastFloor(x);
iy = fastFloor(y);
rx = x - ix;
ry = y - iy;
// gradient indices
int i00, i10, i01, i11;
// Get some random numbers in the range 0-10 for our gradients
i00 = p[(ix + p[iy]) % 255] % 10;
i01 = p[(ix + p[iy+1]) % 255] % 10;
i10 = p[(ix+1 +p[iy]) % 255] % 10;
i11 = p[(ix+1 +p[iy+1]) % 255] % 10;
/*double n01 = noise(ix-1, iy-1);
double n02 = noise(ix+1, iy-1);
double n03 = noise(ix-1, iy+1);
double n04 = noise(ix+1, iy+1);
double n05 = noise(ix-1, iy);
double n06 = noise(ix+1, iy);
double n07 = noise(ix, iy-1);
double n08 = noise(ix, iy+1);
double n09 = noise(ix, iy);
double n12 = noise(ix+2, iy-1);
double n14 = noise(ix+2, iy+1);
double n16 = noise(ix+2, iy);
double n23 = noise(ix-1, iy+2);
double n24 = noise(ix+1, iy+2);
double n28 = noise(ix, iy+2);
double n34 = noise(ix+2, iy+2);
//find the noise values of the four corners
double c00 = 0.0625*(n01+n02+n03+n04) + 0.125*(n05+n06+n07+n08) + 0.25*(n09);
double c10 = 0.0625*(n07+n12+n08+n14) + 0.125*(n09+n16+n02+n04) + 0.25*(n06);
double c01 = 0.0625*(n05+n06+n23+n24) + 0.125*(n03+n04+n09+n28) + 0.25*(n08);
double c11 = 0.0625*(n09+n16+n28+n34) + 0.125*(n08+n14+n06+n24) + 0.25*(n04);
*/
double c00 = dot(grad2[i00], rx, ry);
double c10 = dot(grad2[i10], rx-1, ry);
double c01 = dot(grad2[i01], rx, ry-1);
double c11 = dot(grad2[i11], rx-1, ry-1);
// get faded x and y values
double x_fade, y_fade;
x_fade = fade(rx);
y_fade = fade(ry);
//interpolate
double final_x0, final_x1, final_xy;
// along x
final_x0 = interpolate(c00, c10, x_fade);
final_x1 = interpolate(c01, c11, x_fade);
final_xy = interpolate(final_x0, final_x1, y_fade);
//Skew from [-1, 1] to [0, 1]
final_xy = (final_xy + 1)*0.5f;
//is there another fix?
return final_xy > 1 ? 1 : final_xy;
}
// Generate some random numbers
double TerrainGenerator::noise(int x, int y)
{
int n = x + y * 57;
n = (n << 13) ^ n;
int t = (n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff;
return 1.0 - double(t) * 0.931322574615478515625e-9; /// 1073741824.0);
}
void TerrainGenerator::seedGenerator(int seed)
{
if(!locked)
this->seed = seed;
locked = true;
}
void TerrainGenerator::setFrequency(double frequency)
{
this->frequency = frequency;
}
void TerrainGenerator::setOctaves(double octaves)
{
this->octaves = octaves;
}
void TerrainGenerator::setAmplitude(double amplitude)
{
this->amplitude = amplitude;
}
double TerrainGenerator::interpolate(double a, double b, double t)
{
return (1-t)*a + (t*b);
}
// Fade with the formula 3t^2 - 2t^3
double TerrainGenerator::fade(double t)
{
return t*t*(3 - 2*t);
}
double TerrainGenerator::dot(double vec[], double x, double y)
{
return vec[0]*x + vec[1]*y;
}
int TerrainGenerator::fastFloor(double t)
{
return t == 0 ? t : t > 0 ? (int) t : (int) t-1;
}