raycaster/sfmlcaster.cpp

#include <fmt/core.h>
#include <SFML/Graphics.hpp>
#include <SFML/Graphics/Image.hpp>
#include <numbers>
#include <algorithm>
#include <cmath>
#include "matrix.hpp"
#include <cstdlib>
#include "dbc.hpp"

using matrix::Matrix;
using namespace fmt;

#define texWidth 64 // must be power of two
#define texHeight 64 // must be power of two


#define numSprites 3
#define numTextures 11

struct Sprite {
  double x;
  double y;
  int texture;
};

//parameters for scaling and moving the sprites
#define uDiv 1
#define vDiv 1
#define vMove 0.0

const int RAY_VIEW_WIDTH=1280;
const int RAY_VIEW_HEIGHT=720;
const int RAY_VIEW_X=0;
const int RAY_VIEW_Y=0;

const int SCREEN_HEIGHT=RAY_VIEW_HEIGHT;
const int SCREEN_WIDTH=1280;

Matrix MAP{
  {8,8,8,8,8,8,8,8,8},
  {8,0,2,0,0,0,0,0,8},
  {8,0,7,0,0,5,6,0,8},
  {8,0,0,0,0,0,0,0,8},
  {8,8,0,0,0,0,0,8,8},
  {8,0,0,1,3,4,0,0,8},
  {8,0,0,0,0,0,8,8,8},
  {8,0,0,0,0,0,0,0,8},
  {8,8,8,8,8,8,8,8,8}
};

const int MAP_SIZE=matrix::width(MAP);
const int TILE_SIZE=RAY_VIEW_HEIGHT / MAP_SIZE;
int PITCH=0;
// I chose fixed textures for this instead
const int floorTexture = 3;
const int ceilingTexture = 6;

float player_x = RAY_VIEW_HEIGHT / 2;
float player_y = RAY_VIEW_HEIGHT / 2;

// x and y start position
double posX = player_x / TILE_SIZE;
double posY = player_y / TILE_SIZE;

// initial direction vector
double dirX = -1;
double dirY = 0;

// the 2d raycaster version of camera plane
double planeX = 0;
double planeY = 0.66;

#define rgba_color(r,g,b,a) (r<<(0*8))|(g<<(1*8))|(b<<(2*8))|(a<<(3*8))
#define gray_color(c) rgba_color(c, c, c, 255)

Sprite SPRITE[numSprites] = {
  {3.0, 4.5, 8},
  {3.4, 1.95, 9},
  {7.34, 5.5, 10}
};

double ZBuffer[RAY_VIEW_WIDTH];
int spriteOrder[numSprites];
double spriteDistance[numSprites];

std::vector<uint32_t> texture[numTextures];

#define pixcoord(X, Y) ((Y) * RAY_VIEW_WIDTH) + (X)
uint32_t pixels[RAY_VIEW_WIDTH * RAY_VIEW_HEIGHT] = {0};

sf::Texture view_texture;
sf::Sprite view_sprite;

void sortSprites(int *order, double *dist, int amount);

void loadImage(std::vector<uint32_t>& texture, const char *filename) {
  sf::Image img;
  bool good = img.loadFromFile(filename);
  dbc::check(good, format("failed to load {}", filename));
  uint32_t *pixbuf = (uint32_t *)img.getPixelsPtr();
  std::copy_n(pixbuf, texture.size(), texture.begin());
}

void load_textures() {
  for(int i = 0; i < numTextures; i++) {
    texture[i].resize(texWidth * texHeight);
  }

  loadImage(texture[0], "pics/eagle.png");
  loadImage(texture[1], "pics/redbrick.png");
  loadImage(texture[2], "pics/purplestone.png");
  loadImage(texture[3], "pics/greystone.png");
  loadImage(texture[4], "pics/bluestone.png");
  loadImage(texture[5], "pics/mossy.png");
  loadImage(texture[6], "pics/wood.png");
  loadImage(texture[7], "pics/colorstone.png");

  loadImage(texture[8], "pics/barrel.png");
  loadImage(texture[9], "pics/pillar.png");
  loadImage(texture[10], "pics/greenlight.png");
}

void draw_sfml_rect(sf::RenderWindow &window, sf::Vector2f pos, sf::Vector2f size, uint8_t color) {
  sf::RectangleShape rect(size);
  rect.setFillColor({color, color, color});
  rect.setPosition(pos);
  window.draw(rect);
}

void draw_pixel_buffer(sf::RenderWindow &window) {
  view_texture.update((uint8_t *)pixels, RAY_VIEW_WIDTH, RAY_VIEW_HEIGHT, 0, 0);
  // BUG: can I do this once and just update it?
  window.draw(view_sprite);
}

void draw_map_rect(sf::RenderWindow &window, int x, int y, uint32_t color) {
  draw_sfml_rect(window,
      {float(x * TILE_SIZE), float(y * TILE_SIZE)},
      {float(TILE_SIZE-1), float(TILE_SIZE-1)},
      color);
}

void draw_map(sf::RenderWindow &window, Matrix &map) {
  uint32_t light_grey = gray_color(191);
  uint32_t dark_grey = gray_color(65);

  for(size_t y = 0; y < matrix::height(map); y++) {
    for(size_t x = 0; x < matrix::width(map); x++) {
      draw_map_rect(window, x, y, map[y][x] == 0 ? dark_grey : light_grey);
    }
  }
}

void draw_line(sf::RenderWindow &window, Point start, Point end, uint32_t color) {
  int x = int(start.x);
  int y = int(start.y);
  int x1 = int(end.x);
  int y1 = int(end.y);
  int dx = std::abs(x1 - x);
  int sx = x < x1 ? 1 : -1;
  int dy = std::abs(y1 - y) * -1;
  int sy = y < y1 ? 1 : -1;
  int error = dx + dy;

  while(x != x1 || y != y1) {
    int e2 = 2 * error;

    if(e2 >= dy) {
      error = error + dy;
      x = x + sx;
    }

    if(e2 <= dx) {
      error = error + dx;
      y = y + sy;
    }

    pixels[pixcoord(x,y)] = color;
  }
}

void clear(sf::RenderWindow &window) {
  std::fill_n(pixels, RAY_VIEW_WIDTH * RAY_VIEW_HEIGHT, 0);
  window.clear();
}

void draw_map_blocks(sf::RenderWindow &window, int col, int row) {
  draw_map_rect(window, col, row, rgba_color(100, 20, 20, 255));
}

void ray_casting(sf::RenderWindow &window, Matrix& map) {
  int w = RAY_VIEW_WIDTH;
  int h = RAY_VIEW_HEIGHT;

  // WALL CASTING
  for(int x = 0; x < w; x++) {
    // calculate ray position and direction
    double cameraX = 2 * x / double(w) - 1; // x-coord in camera space
    double rayDirX = dirX + planeX * cameraX;
    double rayDirY = dirY + planeY * cameraX;

    // which box of the map we're in
    int mapX = int(posX);
    int mapY = int(posY);

    // length of ray from current pos to next x or y-side
    double sideDistX;
    double sideDistY;

    // length of ray from one x or y-side to next x or y-side
    double deltaDistX = std::abs(1.0 / rayDirX);
    double deltaDistY = std::abs(1.0 / rayDirY);
    double perpWallDist;

    int stepX = 0;
    int stepY = 0;
    int hit = 0;
    int side = 0;

    // calculate step and initial sideDist
    if(rayDirX < 0) {
      stepX = -1;
      sideDistX = (posX - mapX) * deltaDistX;
    } else {
      stepX = 1;
      sideDistX = (mapX + 1.0 - posX) * deltaDistX;
    }

    if(rayDirY < 0) {
      stepY = -1;
      sideDistY = (posY - mapY) * deltaDistY;
    } else {
      stepY = 1;
      sideDistY = (mapY + 1.0 - posY) * deltaDistY;
    }

    // perform DDA
    while(hit == 0) {
      if(sideDistX < sideDistY) {
        sideDistX += deltaDistX;
        mapX += stepX;
        side = 0;
      } else {
        sideDistY += deltaDistY;
        mapY += stepY;
        side = 1;
      }

      if(map[mapY][mapX] > 0) hit = 1;
    }

    if(side == 0) {
      perpWallDist = (sideDistX - deltaDistX);
    } else {
      perpWallDist = (sideDistY - deltaDistY);
    }

    // draw_map_blocks(window, mapX, mapY);

    int lineHeight = int(h / perpWallDist);

    int drawStart = -lineHeight / 2 + h / 2 + PITCH;
    if(drawStart < 0) drawStart = 0;

    int drawEnd = lineHeight / 2 + h / 2 + PITCH;
    if(drawEnd >= h) drawEnd = h - 1;

    int texNum = MAP[mapY][mapX] - 1;

    // calculate value of wallX
    double wallX;  // where exactly the wall was hit
    if(side == 0) {
      wallX = posY + perpWallDist * rayDirY;
    } else {
      wallX = posX + perpWallDist * rayDirX;
    }
    wallX -= floor((wallX));

    // x coorindate on the texture
    int texX = int(wallX * double(texWidth));
    if(side == 0 && rayDirX > 0) texX = texWidth - texX - 1;
    if(side == 1 && rayDirY < 0) texX = texWidth - texX - 1;

    // LODE: an integer-only bresenham or DDA like algorithm could make the texture coordinate stepping faster

    // How much to increase the texture coordinate per screen pixel
    double step = 1.0 * texHeight / lineHeight;
    // Starting texture coordinate
    double texPos = (drawStart - PITCH - h / 2 + lineHeight / 2) * step;

    for(int y = drawStart; y < drawEnd; y++) {
      int texY = (int)texPos & (texHeight - 1);
      texPos += step;
      uint32_t color = texture[texNum][texHeight * texY + texX];

      pixels[pixcoord(x, y)] = color;
    }

    // SET THE ZBUFFER FOR THE SPRITE CASTING
    ZBuffer[x] = perpWallDist;

  }

  // SPRITE CASTING
  // sort sprites from far to close
  for(int i = 0; i < numSprites; i++) {
    spriteOrder[i] = i;
    // this is just the distance calculation
    spriteDistance[i] = ((posX - SPRITE[i].x) *
        (posX - SPRITE[i].x) +
        (posY - SPRITE[i].y) *
        (posY - SPRITE[i].y));
  }

  sortSprites(spriteOrder, spriteDistance, numSprites);

  // after sorting the sprites, do the projection
  for(int i = 0; i < numSprites; i++) {
    int sprite_index = spriteOrder[i];
    double spriteX = SPRITE[sprite_index].x - posX;
    double spriteY = SPRITE[sprite_index].y - posY;
    int sprite_texture_number = SPRITE[sprite_index].texture;
    auto sprite_texture = texture[sprite_texture_number];

    //transform sprite with the inverse camera matrix
    // [ planeX   dirX ] -1                                       [ dirY      -dirX ]
    // [               ]       =  1/(planeX*dirY-dirX*planeY) *   [                 ]
    // [ planeY   dirY ]                                          [ -planeY  planeX ]

    double invDet = 1.0 / (planeX * dirY - dirX * planeY); // required for correct matrix multiplication

    double transformX = invDet * (dirY * spriteX - dirX * spriteY);
    //this is actually the depth inside the screen, that what Z is in 3D, the distance of sprite to player, matching sqrt(spriteDistance[i])

    double transformY = invDet * (-planeY * spriteX + planeX * spriteY);

    int spriteScreenX = int((w / 2) * (1 + transformX / transformY));

    int vMoveScreen = int(vMove / transformY);

    // calculate the height of the sprite on screen
    //using "transformY" instead of the real distance prevents fisheye
    int spriteHeight = abs(int(h / transformY)) / vDiv;

    //calculate lowest and highest pixel to fill in current stripe
    int drawStartY = -spriteHeight / 2 + h / 2 + vMoveScreen;
    if(drawStartY < 0) drawStartY = 0;
    int drawEndY = spriteHeight / 2 + h / 2 + vMoveScreen;
    if(drawEndY >= h) drawEndY = h - 1;

    // calculate width the the sprite
    // same as height of sprite, given that it's square
    int spriteWidth = abs(int(h / transformY)) / uDiv;
    int drawStartX = -spriteWidth / 2 + spriteScreenX;
    if(drawStartX < 0) drawStartX = 0;
    int drawEndX = spriteWidth / 2 + spriteScreenX;
    if(drawEndX > w) drawEndX = w;

    //loop through every vertical stripe of the sprite on screen
    for(int stripe = drawStartX; stripe < drawEndX; stripe++) {
      int texX = int(256 * (stripe - (-spriteWidth / 2 + spriteScreenX)) * texWidth / spriteWidth) / 256;
      // the conditions in the if are:
      // 1) it's in front of the camera plane so you don't see things behind you
      // 2) ZBuffer, with perpendicular distance
      if(transformY > 0 && transformY < ZBuffer[stripe]) {
        for(int y = drawStartY; y < drawEndY; y++) {
          //256 and 128 factors to avoid floats
          int d = (y - vMoveScreen) * 256 - h * 128 + spriteHeight * 128;
          int texY = ((d * texHeight) / spriteHeight) / 256;
          //get current color from the texture
          uint32_t color = sprite_texture[texWidth * texY + texX];
          // poor person's transparency, get current color from the texture
          if((color & 0x00FFFFFF) != 0) {
            pixels[pixcoord(stripe, y)] = color;
          }
        }
      }
    }
  }
}

void draw_ceiling_floor(sf::RenderWindow &window) {
  int screenHeight = RAY_VIEW_HEIGHT;
  int screenWidth = RAY_VIEW_WIDTH;

  for(int y = screenHeight / 2 + 1; y < screenHeight; ++y) {
    // rayDir for leftmost ray (x=0) and rightmost (x = w)
    float rayDirX0 = dirX - planeX;
    float rayDirY0 = dirY - planeY;
    float rayDirX1 = dirX + planeX;
    float rayDirY1 = dirY + planeY;

    // current y position compared to the horizon
    int p = y - screenHeight / 2;

    // vertical position of the camera
    // 0.5 will the camera at the center horizon. For a
    // different value you need a separate loop for ceiling
    // and floor since they're no longer symmetrical.
    float posZ = 0.5 * screenHeight;

    // horizontal distance from the camera to the floor for the current row
    // 0.5 is the z position exactly in the middle between floor and ceiling
    // See NOTE in Lode's code for more.
    float rowDistance = posZ / p;

    // calculate the real world step vector we have to add for each x (parallel to camera plane)
    // adding step by step avoids multiplications with a wight in the inner loop
    float floorStepX = rowDistance * (rayDirX1 - rayDirX0) / screenWidth;
    float floorStepY = rowDistance * (rayDirY1 - rayDirY0) / screenWidth;


    // real world coordinates of the leftmost column.
    // This will be updated as we step to the right
    float floorX = posX + rowDistance * rayDirX0;
    float floorY = posY + rowDistance * rayDirY0;

    for(int x = 0; x < screenWidth; ++x) {
      // the cell coord is simply taken from the int parts of
      // floorX and floorY.
      int cellX = int(floorX);
      int cellY = int(floorY);

      // get the texture coordinat from the fractional part
      int tx = int(texWidth * (floorX - cellX)) & (texWidth - 1);
      int ty = int(texWidth * (floorY - cellY)) & (texHeight - 1);

      floorX += floorStepX;
      floorY += floorStepY;

      // now get the pixel from the texture
      uint32_t color;
      // this uses the previous ty/tx fractional parts of
      // floorX cellX to find the texture x/y. How?

      // FLOOR
      color = texture[floorTexture][texWidth * ty + tx];
      pixels[pixcoord(x, y)] = color;

      // CEILING
      color = texture[ceilingTexture][texWidth * ty + tx];
      pixels[pixcoord(x, screenHeight - y - 1)] = color;
    }
  }
}

void draw_everything(sf::RenderWindow &window) {
  clear(window);
  // draw_map(window, MAP);
  draw_ceiling_floor(window);
  ray_casting(window, MAP);
  draw_pixel_buffer(window);
  window.display();
}

bool empty_space(int new_x, int new_y) {
  dbc::check((size_t)new_x < matrix::width(MAP),
      format("x={} too wide={}", new_x, matrix::width(MAP)));
  dbc::check((size_t)new_y < matrix::height(MAP),
      format("y={} too high={}", new_y, matrix::height(MAP)));

  return MAP[new_y][new_x] == 0;
}

int main() {
  using KB = sf::Keyboard;
  sf::RenderWindow window(sf::VideoMode(SCREEN_WIDTH, SCREEN_HEIGHT), "SFMLCaster");

  window.setVerticalSyncEnabled(true);
  view_texture.create(RAY_VIEW_WIDTH, RAY_VIEW_HEIGHT);
  view_sprite.setTexture(view_texture);
  view_sprite.setPosition(RAY_VIEW_X, 0);

  load_textures();

  double moveSpeed = 0.1;
  double rotSpeed = 0.1;

  while(window.isOpen()) {
    draw_everything(window);

    if(KB::isKeyPressed(KB::X)) {
      println("player position: {},{}",
          posX, posY);
    }

    if(KB::isKeyPressed(KB::W)) {
        if(empty_space(int(posX + dirX * moveSpeed), int(posY))) posX += dirX * moveSpeed;
        if(empty_space(int(posX), int(posY + dirY * moveSpeed))) posY += dirY * moveSpeed;
    } else if(KB::isKeyPressed(KB::S)) {
        if(empty_space(int(posX - dirX * moveSpeed), int(posY))) posX -= dirX * moveSpeed;
        if(empty_space(int(posX), int(posY - dirY * moveSpeed))) posY -= dirY * moveSpeed;
    }

    if(KB::isKeyPressed(KB::D)) {
      double oldDirX = dirX;
      dirX = dirX * cos(-rotSpeed) - dirY * sin(-rotSpeed);
      dirY = oldDirX * sin(-rotSpeed) + dirY * cos(-rotSpeed);

      double oldPlaneX = planeX;
      planeX = planeX * cos(-rotSpeed) - planeY * sin(-rotSpeed);
      planeY = oldPlaneX * sin(-rotSpeed) + planeY * cos(-rotSpeed);
    } else if(KB::isKeyPressed(KB::A)) {
      double oldDirX = dirX;
      dirX = dirX * cos(rotSpeed) - dirY * sin(rotSpeed);
      dirY = oldDirX * sin(rotSpeed) + dirY * cos(rotSpeed);

      double oldPlaneX = planeX;
      planeX = planeX * cos(rotSpeed) - planeY * sin(rotSpeed);
      planeY = oldPlaneX * sin(rotSpeed) + planeY * cos(rotSpeed);
    }

    if(KB::isKeyPressed(KB::E)) {
      println("PITCH DISABLED");
      // PITCH = std::clamp(PITCH + 10, -60, 240);
    } else if(KB::isKeyPressed(KB::Q)) {
      println("PITCH DISABLED");
      // PITCH = std::clamp(PITCH - 10, -60, 240);
    }

    sf::Event event;
    while(window.pollEvent(event)) {
      if(event.type == sf::Event::Closed) {
        window.close();
      }
    }

  }

  return 0;
}

void sortSprites(int* order, double* dist, int amount)
{
  std::vector<std::pair<double, int>> sprites(amount);

  for(int i = 0; i < amount; i++) {
    sprites[i].first = dist[i];
    sprites[i].second = order[i];
  }

  std::sort(sprites.begin(), sprites.end());

  // restore in reverse order
  for(int i = 0; i < amount; i++) {
    dist[i] = sprites[amount - i - 1].first;
    order[i] = sprites[amount - i - 1].second;
  }
}