#include <stdio.h>
#include <math.h>
#include <stdlib.h>
const int max_iterations = 128;
const double stop_threshold = 0.01;
const double grad_step = 0.01;
const double clip_far = 10.0;
const double PI = 3.14159265359;
const double PI2 = 6.28318530718;
const double DEG_TO_RAD = PI / 180.0;
typedef struct { double x, y; } vec2;
typedef struct { double x, y, z; } vec3;
typedef struct { double m[9]; } mat3;
const vec3 light_pos = { 20.0, 50.0, 20.0 };
double min(double a, double b) { return a < b ? a : b; }
double max(double a, double b) { return a > b ? a : b; }
double clamp(double f, double a, double b) { return max(min(f, b), a); }
vec2 make2(double x, double y) { vec2 r = { x, y }; return r; }
vec2 add2(vec2 a, vec2 b) { vec2 r = { a.x + b.x, a.y + b.y }; return r; }
vec2 sub2(vec2 a, vec2 b) { vec2 r = { a.x - b.x, a.y - b.y }; return r; }
double dot2(vec2 a, vec2 b) { return a.x * b.x + a.y * b.y; }
double length2(vec2 v) { return sqrt(dot2(v, v)); }
vec3 make3(double x, double y, double z) { vec3 r = { x, y, z }; return r; }
vec3 add3(vec3 a, vec3 b) { vec3 r = { a.x + b.x, a.y + b.y, a.z + b.z }; return r; }
vec3 sub3(vec3 a, vec3 b) { vec3 r = { a.x - b.x, a.y - b.y, a.z - b.z }; return r; }
vec3 mul3(vec3 a, vec3 b) { vec3 r = { a.x * b.x, a.y * b.y, a.z * b.z }; return r; }
vec3 scale3(vec3 v, double s) { vec3 r = { v.x * s, v.y * s, v.z * s }; return r; }
double dot3(vec3 a, vec3 b) { return a.x * b.x + a.y * b.y + a.z * b.z; }
double length3(vec3 v) { return sqrt(dot3(v, v)); }
vec3 normalize3(vec3 v) { return scale3(v, 1.0 / length3(v)); }
vec3 mul(mat3 m, vec3 v) {
return make3(
m.m[0] * v.x + m.m[3] * v.y + m.m[6] * v.z,
m.m[1] * v.x + m.m[4] * v.y + m.m[7] * v.z,
m.m[2] * v.x + m.m[5] * v.y + m.m[8] * v.z);
}
mat3 rotationXY(double x, double y) {
vec2 c = { cos(x), cos(y) };
vec2 s = { sin(x), sin(y) };
mat3 m = {
c.y , 0.0, -s.y,
s.y * s.x, c.x, c.y * s.x,
s.y * c.x, -s.x, c.y * c.x
};
return m;
}
double opI(double d1, double d2) { return max(d1, d2); }
double opU(double d1, double d2) { return min(d1, d2); }
double opS(double d1, double d2) { return max(-d1, d2); }
double sdPetal(vec3 p, double s) {
p = add3(mul3(p, make3(0.8, 1.5, 0.8)), make3(0.1, 0.0, 0.0));
vec2 q = make2(length2(make2(p.x, p.z)), p.y);
double lower = length2(q) - 1.0;
lower = opS(length2(q) - 0.97, lower);
lower = opI(lower, q.y);
double upper = length2(sub2(q, make2(s, 0.0))) + 1.0 - s;
upper = opS(upper, length2(sub2(q, make2(s, 0.0))) + 0.97 - s);
upper = opI(upper, -q.y);
upper = opI(upper, q.x - 2.0);
double region = length3(sub3(p, make3(1.0, 0.0, 0.0))) - 1.0;
return opI(opU(upper, lower), region);
}
double map(vec3 p) {
double d = 1000.0, s = 2.0;
mat3 r = rotationXY(0.1, PI2 * 0.618034);
r.m[0] *= 1.08; r.m[1] *= 1.08; r.m[2] *= 1.08;
r.m[3] *= 0.995; r.m[4] *= 0.995; r.m[5] *= 0.995;
r.m[6] *= 1.08; r.m[7] *= 1.08; r.m[8] *= 1.08;
for (int i = 0; i < 21; i++) {
d = opU(d, sdPetal(p, s));
p = mul(r, p);
p = add3(p, make3(0.0, -0.02, 0.0));
s *= 1.05;
}
return d;
}
vec3 gradient(vec3 pos) {
const vec3 dx = { grad_step, 0.0, 0.0 };
const vec3 dy = { 0.0, grad_step, 0.0 };
const vec3 dz = { 0.0, 0.0, grad_step };
return normalize3(make3(
map(add3(pos, dx)) - map(sub3(pos, dx)),
map(add3(pos, dy)) - map(sub3(pos, dy)),
map(add3(pos, dz)) - map(sub3(pos, dz))));
}
double ray_marching(vec3 origin, vec3 dir, double start, double end) {
double depth = start;
for (int i = 0; i < max_iterations; i++) {
double dist = map(add3(origin, scale3(dir, depth)));
if (dist < stop_threshold)
return depth;
depth += dist * 0.3;
if (depth >= end)
return end;
}
return end;
}
double shading(vec3 v, vec3 n, vec3 eye) {
vec3 ev = normalize3(sub3(v, eye));
vec3 vl = normalize3(sub3(light_pos, v));
double diffuse = dot3(vl, n) * 0.5 + 0.5;
double rim = pow(1.0 - max(-dot3(n, ev), 0.0), 2.0) * 0.15;
double ao = clamp(v.y * 0.5 + 0.5, 0.0, 1.0);
return (diffuse + rim) * ao;
}
vec3 ray_dir(double fov, vec2 pos) {
vec3 r = { pos.x, pos.y, -tan((90.0 - fov * 0.5) * DEG_TO_RAD) };
return normalize3(r);
}
double f(vec2 fragCoord) {
vec3 dir = ray_dir(45.0, fragCoord);
vec3 eye = { 0.0, 0.0, 4.5 };
mat3 rot = rotationXY(-1.0, 1.0);
dir = mul(rot, dir);
eye = mul(rot, eye);
double depth = ray_marching(eye, dir, 0.0, clip_far);
vec3 pos = add3(eye, scale3(dir, depth));
if (depth >= clip_far)
return 0.0;
else
return shading(pos, gradient(pos), eye);
}
int main(int argc, char* argv[]) {
getchar();
for (int y = 0; y < 80; y++) {
for (int x = 0; x < 160; x++)
putchar(" .,-:;+=*#@"[(int)(f(make2((x / 160.0 - 0.5) * 2.0, (y / 80.0 - 0.5) * -2.0)) * 12.0)]);
putchar('\n');
}
system("color 0c");
getchar();
return 0;
}
