// rndmap.cpp: perlin noise landscape generation and some experimental random
// map stuff, currently not used
#include "cube.h"
float
noise(int x, int y, int seed)
{
int n = x + y * 57;
n = (n << 13) ^ n;
return 1.0f -
((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) /
1073741824.0f;
}
float
smoothednoise(int x, int y, int seed)
{
float corners =
(noise(x - 1, y - 1, seed) + noise(x + 1, y - 1, seed) +
noise(x - 1, y + 1, seed) + noise(x + 1, y + 1, seed)) /
16;
float sides = (noise(x - 1, y, seed) + noise(x + 1, y, seed) +
noise(x, y - 1, seed) + noise(x, y + 1, seed)) /
8;
float center = noise(x, y, seed) / 4;
return corners + sides + center;
}
float
interpolate(float a, float b, float x)
{
float ft = x * 3.1415927f;
float f = (1.0f - (float)cos(ft)) * 0.5f;
return a * (1 - f) + b * f;
}
float
interpolatednoise(float x, float y, int seed)
{
int ix = (int)x;
float fx = x - ix;
int iy = (int)y;
float fy = y - iy;
float v1 = smoothednoise(ix, iy, seed);
float v2 = smoothednoise(ix + 1, iy, seed);
float v3 = smoothednoise(ix, iy + 1, seed);
float v4 = smoothednoise(ix + 1, iy + 1, seed);
float i1 = interpolate(v1, v2, fx);
float i2 = interpolate(v3, v4, fy);
return interpolate(i1, i2, fy);
}
float
perlinnoise_2D(float x, float y, int seedstep, float pers)
{
float total = 0;
int seed = 0;
for (int i = 0; i < 7; i++) {
float frequency = (float)(2 ^ i);
float amplitude = (float)pow(pers, i);
total += interpolatednoise(x * frequency, y * frequency, seed) *
amplitude;
seed += seedstep;
}
return total;
}
void
perlinarea(block &b, int scale, int seed, int psize)
{
srand(seed);
seed = rnd(10000);
if (!scale)
scale = 10;
for (int x = b.x; x <= b.x + b.xs; x++)
for (int y = b.y; y <= b.y + b.ys; y++) {
sqr *s = S(x, y);
if (!SOLID(s) && x != b.x + b.xs && y != b.y + b.ys)
s->type = FHF;
s->vdelta =
(int)(perlinnoise_2D(x / ((float)scale) + seed,
y / ((float)scale) + seed, 1000, 0.01f) *
50 +
25);
if (s->vdelta > 128)
s->vdelta = 0;
};
}