用C语言50行代码绘制一朵玫瑰花

先看看效果图

代码在这里奥

#include
#include
const int max_iteratiOns= 128;
const float stop_threshold = 0.01f;
const float grad_step = 0.01f;
const float clip_far = 10.0f;
const float PI = 3.14159265359f;
const float PI2 = 6.28318530718f;
const float DEG_TO_RAD = PI / 180.0f;
typedef struct { float x, y; } vec2;
typedef struct { float x, y, z; } vec3;
typedef struct { float m[9]; } mat3;
const vec3 light_pos = { 20.0f, 50.0f, 20.0f };
float min(float a, float b) { return a float max(float a, float b) { return a > b ? a : b; }
float clamp(float f, float a, float b) { return max(min(f, b), a); }
vec2 make2(float x, float 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; }
float dot2(vec2 a, vec2 b) { return a.x * b.x + a.y * b.y; }
float length2(vec2 v) { return sqrt(dot2(v, v)); }
vec3 make3(float x, float y, float 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, float s) { vec3 r = { v.x * s, v.y * s, v.z * s }; return r; }
float dot3(vec3 a, vec3 b) { return a.x * b.x + a.y * b.y + a.z * b.z; }
float length3(vec3 v) { return sqrt(dot3(v, v)); }
vec3 normalize3(vec3 v) { return scale3(v, 1.0f / 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(float x, float y) {
vec2 c = { cos(x), cos(y) }, s = { sin(x), sin(y) };
mat3 m = {
c.y , 0.0f, -s.y,
s.y * s.x, c.x, c.y * s.x,
s.y * c.x, -s.x, c.y * c.x
};
return m;
}
float opI(float d1, float d2) { return max(d1, d2); }
float opU(float d1, float d2) { return min(d1, d2); }
float opS(float d1, float d2) { return max(-d1, d2); }
float sdPetal(vec3 p, float s) {
p = add3(mul3(p, make3(0.8f, 1.5f, 0.8f)), make3(0.1f, 0.0f, 0.0f));
vec2 q = make2(length2(make2(p.x, p.z)), p.y);
float lower = length2(q) - 1.0f;
lower = opS(length2(q) - 0.97f, lower);
lower = opI(lower, q.y);
float upper = length2(sub2(q, make2(s, 0.0f))) + 1.0f - s;
upper = opS(upper, length2(sub2(q, make2(s, 0.0f))) + 0.97f - s);
upper = opI(upper, -q.y);
upper = opI(upper, q.x - 2.0f);
float region = length3(sub3(p, make3(1.0f, 0.0f, 0.0f))) - 1.0f;
return opI(opU(upper, lower), region);
}
float map(vec3 p) {
float d = 1000.0f, s = 2.0f;
mat3 r = rotationXY(0.1f, PI2 * 0.618034f);
r.m[0] *= 1.08f; r.m[1] *= 1.08f; r.m[2] *= 1.08f;
r.m[3] *= 0.995f; r.m[4] *= 0.995f; r.m[5] *= 0.995f;
r.m[6] *= 1.08f; r.m[7] *= 1.08f; r.m[8] *= 1.08f;
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 *= 1.05f;
}
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))));
}
float ray_marching(vec3 origin, vec3 dir, float start, float end) {
float depth = start;
for (int i = 0; i float dist = map(add3(origin, scale3(dir, depth)));
if (dist return depth;
depth += dist * 0.3;
if (depth >= end)
return end;
}
return end;
}
float shading(vec3 v, vec3 n, vec3 eye) {
vec3 ev = normalize3(sub3(v, eye));
vec3 vl = normalize3(sub3(light_pos, v));
float diffuse = dot3(vl, n) * 0.5f + 0.5f;
vec3 h = normalize3(sub3(vl, ev));
float rim = pow(1.0f - max(-dot3(n, ev), 0.0f), 2.0f) * 0.15f;
float ao = clamp(v.y * 0.5f + 0.5f, 0.0f, 1.0f);
return (diffuse + rim) * ao;
}
vec3 ray_dir(float fov, vec2 pos) {
vec3 r = { pos.x, pos.y, -tan((90.0f - fov * 0.5f) * DEG_TO_RAD) };
return normalize3(r);
}
float f(vec2 fragCoord) {
vec3 dir = ray_dir(45.0f, fragCoord);
vec3 eye = { 0.0f, 0.0f, 4.5f };
mat3 rot = rotationXY(-1.0f, 1.0f);
dir = mul(rot, dir);
eye = mul(rot, eye);
float depth = ray_marching(eye, dir, 0.0f, clip_far);
vec3 pos = add3(eye, scale3(dir, depth));
if (depth >= clip_far)
return 0.0f;
else
return shading(pos, gradient(pos), eye);
}
int main() {
puts("\033[91m");
for (int y = 0; y <80; y++) {
for (int x = 0; x <160; x++)
putchar(" .,-:;+=*#@"[(int)(f(make2((x / 160.0f - 0.5f) * 2.0f, (y / 80.0f - 0.5f) * -2.0f)) * 12.0f)]);
putchar('\n');
}
}

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