utils.h

#pragma once

#include <chrono>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <thread>
#include <vector>

#define PI 3.1415
#define EPSILON 0.00001f
#define BIG_EPSILON 0.01f

// dark ---> bright
const char *COLOR_STRONG =
    "@@@@@@@@@@%%%%%%%%#########*********++++++++===:::...  ";
const char *COLOR_LIGHT = "******+++===----:::::::::::...... ";

// not very interesting
struct vec3 {
  float x;
  float y;
  float z;
  vec3(float x, float y, float z) : x(x), y(y), z(z) {}
  inline void show() { printf("vec3 %f %f %f", x, y, z); }
};

// I know it looks ugly
struct mat4 {

  float m00, m01, m02, m03, m10, m11, m12, m13, m20, m21, m22, m23, m30, m31,
      m32, m33;

  mat4(float m00, float m01, float m02, float m03, float m10, float m11,
       float m12, float m13, float m20, float m21, float m22, float m23,
       float m30, float m31, float m32, float m33)
      : m00(m00), m01(m01), m02(m02), m03(m03), m10(m10), m11(m11), m12(m12),
        m13(m13), m20(m20), m21(m21), m22(m22), m23(m23), m30(m30), m31(m31),
        m32(m32), m33(m33) {}
};

struct t_screen {

  float width, height;
  std::vector<std::vector<char>> pixels;

  t_screen(float w, float h) {
    this->width = w;
    this->height = h;
    for (int i = 0; i < (int)height; i++) {
      std::vector<char> row;
      for (int j = 0; j < (int)width; j++)
        row.push_back(' ');
      pixels.push_back(row);
    }
  }

  inline char computeColorGivenDiffuseLight(float light,
                                            const char *palette = COLOR_LIGHT) {
    float len = (float)strlen(palette);
    int index = std::min(std::max(0, (int)(light * len)), (int)(len - 1));
    // reverse
    return palette[(int)len - index - 1];
  }

  inline void put(int y, int x, char pixel) {
    if (x < 0 || x >= (int)width || y >= (int)height || y < 0)
      return;
    pixels[y][x] = pixel;
  }

  inline void show() {
    for (int i = 0; i < (int)height; i++) {
      for (int j = 0; j < (int)width; std::cout << pixels[i][j], j++)
        ;
      std::cout << '\n';
    }
  }

  inline void saveCursor() { std::cout << "\033[s"; }

  inline void restoreCursor() { std::cout << "\033[u"; }

  inline void clear() {
    for (int i = 0; i < (int)height; i++)
      for (int j = 0; j < (int)width; pixels[i][j] = ' ', j++)
        ;
#ifdef _WIN32
    system("cls");
#else
    system("clear");
#endif
  }
};

inline float length(vec3 a) {
  return (float)sqrt(a.x * a.x + a.y * a.y + a.z * a.z);
}

inline vec3 scaleReal(vec3 a, float k) { return {a.x * k, a.y * k, a.z * k}; }

inline vec3 add(vec3 a, vec3 b) { return {a.x + b.x, a.y + b.y, a.z + b.z}; }

inline vec3 sub(vec3 a, vec3 b) { return add(a, scaleReal(b, -1.)); }

inline float dot(vec3 a, vec3 b) { return a.x * b.x + a.y * b.y + a.z * b.z; }

inline vec3 v_max(vec3 a, vec3 b) {
  return {std::max(a.x, b.x), std::max(a.y, b.y), std::max(a.z, b.z)};
}

inline vec3 v_min(vec3 a, vec3 b) {
  return {std::min(a.x, b.x), std::min(a.y, b.y), std::min(a.z, b.z)};
}

inline vec3 normalize(vec3 a) {
  const float L = length(a);
  if (L <= EPSILON)
    return {0., 0., 0.};
  return {a.x / L, a.y / L, a.z / L};
}

inline vec3 applyTransf(mat4 m, vec3 v) {
  const float x = m.m00 * v.x + m.m01 * v.y + m.m02 * v.z + m.m03 * 1.;
  const float y = m.m10 * v.x + m.m11 * v.y + m.m12 * v.z + m.m13 * 1.;
  const float z = m.m20 * v.x + m.m21 * v.y + m.m22 * v.z + m.m23 * 1.;
  const float w = m.m30 * v.x + m.m31 * v.y + m.m32 * v.z + m.m33 * 1.;
  vec3 res{x, y, z};
  if (fabs(w) > EPSILON)
    return scaleReal(res, 1. / w);
  return res;
}

// basic transformations
inline mat4 rotateY(float t) {
  const float ct = std::cos(t);
  const float st = std::sin(t);
  return mat4(ct, 0, -st, 0, 0, 1, 0, 0, st, 0, ct, 0, 0, 0, 0, 1);
}

inline mat4 rotateZ(float t) {
  const float ct = std::cos(t);
  const float st = std::sin(t);
  return mat4(ct, -st, 0, 0, st, ct, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1);
}

inline mat4 rotateX(float t) {
  const float ct = std::cos(t);
  const float st = std::sin(t);
  return mat4(1, 0, 0, 0, 0, ct, st, 0, 0, -st, ct, 0, 0, 0, 0, 1);
}

// shapes
inline float sdSphere(vec3 p, float radius) { return length(p) - radius; }

inline float sdBox(vec3 p, vec3 b) {
  return length(vec3( // vmax
      (float)std::max((float)(fabs(p.x) - b.x), 0.f),
      (float)std::max((float)(fabs(p.y) - b.y), 0.f),
      (float)std::max((float)(fabs(p.z) - b.z), 0.f)));
}

inline float sdTorus(vec3 p, float tx, float ty) {
  return -ty + sqrt(p.y * p.y + std::pow(sqrt(p.x * p.x + p.z * p.z) - tx, 2));
}

inline float sdUnion(float distA, float distB) {
  return std::min(distA, distB);
}

inline float sdInter(float distA, float distB) {
  return std::max(distA, distB);
}

inline float sdDiff(float distA, float distB) {
  return std::max(distA, -distB);
}

inline vec3 lerp3(vec3 colorone, vec3 colortwo, float value) {
  return add(colorone, scaleReal(sub(colortwo, colorone), value));
}

inline float lerp(float colorone, float colortwo, float value) {
  return lerp3(vec3(colorone, 0., 0.), vec3(colortwo, 0., 0.), value).x;
}

inline float clamp(float value, float min, float max) {
  return std::max(min, std::min(max, value));
}

inline float sdRoundedCylinder(vec3 p, float ra, float rb, float h) {
  const vec3 d =
      vec3(length({p.x, 0., p.z}) - 2.0 * ra + rb, fabs(p.y) - h, 0.);
  return std::min(std::max(d.x, d.y), 0.f) + length(v_max(d, {0., 0., 0.})) -
         rb;
}

inline float sdSmoothSubtraction(float d1, float d2, float k) {
  const float h = clamp(0.5 - 0.5 * (d2 + d1) / k, 0.0, 1.0);
  return lerp(d2, -d1, h) + k * h * (1.0 - h);
}

inline float step(float a, float edge) {
  if (a < edge)
    return 1.;
  return 0.;
}

inline float fixed_fmod(float a, float n) {
  return std::fmod(std::fmod(a, n) + n, n);
}

// for ray marching the gradient at the contact point is orthogonal to the
// surface, approximating it is enough in practice
inline vec3 sceneNormalAt(vec3 p, float (*dist)(vec3)) {
  const float x =
      dist({p.x + EPSILON, p.y, p.z}) - dist({p.x - EPSILON, p.y, p.z});
  const float y =
      dist({p.x, p.y + EPSILON, p.z}) - dist({p.x, p.y - EPSILON, p.z});
  const float z =
      dist({p.x, p.y, p.z + EPSILON}) - dist({p.x, p.y, p.z - EPSILON});
  return normalize({x, y, z});
}