/*
Copyright (c) 2004-2019, Lode Vandevenne

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <cmath>
#include <string>
#include <vector>
#include <iostream>

#include "quickcg.h"
using namespace QuickCG;

/*
g++ *.cpp -lSDL -O3 -W -Wall -ansi -pedantic
g++ *.cpp -lSDL
*/


#define screenWidth 640
#define screenHeight 480
#define texWidth 64
#define texHeight 64
#define mapWidth 24
#define mapHeight 24

int worldMap[mapWidth][mapHeight]=
{
  {4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,7,7,7,7,7,7,7,7},
  {4,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,7,0,0,0,0,0,0,7},
  {4,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,7},
  {4,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,7},
  {4,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,7,0,0,0,0,0,0,7},
  {4,0,4,0,0,0,0,5,5,5,5,5,5,5,5,5,7,7,0,7,7,7,7,7},
  {4,0,5,0,0,0,0,5,0,5,0,5,0,5,0,5,7,0,0,0,7,7,7,1},
  {4,0,6,0,0,0,0,5,0,0,0,0,0,0,0,5,7,0,0,0,0,0,0,8},
  {4,0,7,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,7,7,7,1},
  {4,0,8,0,0,0,0,5,0,0,0,0,0,0,0,5,7,0,0,0,0,0,0,8},
  {4,0,0,0,0,0,0,5,0,0,0,0,0,0,0,5,7,0,0,0,7,7,7,1},
  {4,0,0,0,0,0,0,5,5,5,5,0,5,5,5,5,7,7,7,7,7,7,7,1},
  {6,6,6,6,6,6,6,6,6,6,6,0,6,6,6,6,6,6,6,6,6,6,6,6},
  {8,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4},
  {6,6,6,6,6,6,0,6,6,6,6,0,6,6,6,6,6,6,6,6,6,6,6,6},
  {4,4,4,4,4,4,0,4,4,4,6,0,6,2,2,2,2,2,2,2,3,3,3,3},
  {4,0,0,0,0,0,0,0,0,4,6,0,6,2,0,0,0,0,0,2,0,0,0,2},
  {4,0,0,0,0,0,0,0,0,0,0,0,6,2,0,0,5,0,0,2,0,0,0,2},
  {4,0,0,0,0,0,0,0,0,4,6,0,6,2,0,0,0,0,0,2,2,0,2,2},
  {4,0,6,0,6,0,0,0,0,4,6,0,0,0,0,0,5,0,0,0,0,0,0,2},
  {4,0,0,5,0,0,0,0,0,4,6,0,6,2,0,0,0,0,0,2,2,0,2,2},
  {4,0,6,0,6,0,0,0,0,4,6,0,6,2,0,0,5,0,0,2,0,0,0,2},
  {4,0,0,0,0,0,0,0,0,4,6,0,6,2,0,0,0,0,0,2,0,0,0,2},
  {4,4,4,4,4,4,4,4,4,4,1,1,1,2,2,2,2,2,2,3,3,3,3,3}
};

Uint32 buffer[screenHeight][screenWidth];

int main(int /*argc*/, char */*argv*/[])
{
  double posX = 22.0, posY = 11.5;  //x and y start position
  double dirX = -1.0, dirY = 0.0; //initial direction vector
  double planeX = 0.0, planeY = 0.66; //the 2d raycaster version of camera plane

  double time = 0; //time of current frame
  double oldTime = 0; //time of previous frame

  std::vector<Uint32> texture[8];
  for(int i = 0; i < 8; i++) texture[i].resize(texWidth * texHeight);

  screen(screenWidth,screenHeight, 0, "Raycaster");

  //generate some textures
#if 0
  for(int x = 0; x < texWidth; x++)
  for(int y = 0; y < texHeight; y++)
  {
    int xorcolor = (x * 256 / texWidth) ^ (y * 256 / texHeight);
    //int xcolor = x * 256 / texWidth;
    int ycolor = y * 256 / texHeight;
    int xycolor = y * 128 / texHeight + x * 128 / texWidth;
    texture[0][texWidth * y + x] = 65536 * 254 * (x != y && x != texWidth - y); //flat red texture with black cross
    texture[1][texWidth * y + x] = xycolor + 256 * xycolor + 65536 * xycolor; //sloped greyscale
    texture[2][texWidth * y + x] = 256 * xycolor + 65536 * xycolor; //sloped yellow gradient
    texture[3][texWidth * y + x] = xorcolor + 256 * xorcolor + 65536 * xorcolor; //xor greyscale
    texture[4][texWidth * y + x] = 256 * xorcolor; //xor green
    texture[5][texWidth * y + x] = 65536 * 192 * (x % 16 && y % 16); //red bricks
    texture[6][texWidth * y + x] = 65536 * ycolor; //red gradient
    texture[7][texWidth * y + x] = 128 + 256 * 128 + 65536 * 128; //flat grey texture
  }
#else
 //generate some textures
  unsigned long tw, th;
  loadImage(texture[0], tw, th, "pics/eagle.png");
  loadImage(texture[1], tw, th, "pics/redbrick.png");
  loadImage(texture[2], tw, th, "pics/purplestone.png");
  loadImage(texture[3], tw, th, "pics/greystone.png");
  loadImage(texture[4], tw, th, "pics/bluestone.png");
  loadImage(texture[5], tw, th, "pics/mossy.png");
  loadImage(texture[6], tw, th, "pics/wood.png");
  loadImage(texture[7], tw, th, "pics/colorstone.png");
#endif

  //start the main loop
  while(!done())
  {
    for(int x = 0; x < w; x++)
    {
      //calculate ray position and direction
      double cameraX = 2 * x / (double)w - 1; //x-coordinate 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 position 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 = (rayDirX == 0) ? 1e30 : std::abs(1 / rayDirX);
      double deltaDistY = (rayDirY == 0) ? 1e30 : std::abs(1 / rayDirY);
      double perpWallDist;

      //what direction to step in x or y-direction (either +1 or -1)
      int stepX;
      int stepY;

      int hit = 0; //was there a wall hit?
      int side; //was a NS or a EW wall hit?

      //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)
      {
        //jump to next map square, either in x-direction, or in y-direction
        if(sideDistX < sideDistY)
        {
          sideDistX += deltaDistX;
          mapX += stepX;
          side = 0;
        }
        else
        {
          sideDistY += deltaDistY;
          mapY += stepY;
          side = 1;
        }
        //Check if ray has hit a wall
        if(worldMap[mapX][mapY] > 0) hit = 1;
      }

      //Calculate distance of perpendicular ray (Euclidean distance would give fisheye effect!)
      if(side == 0) perpWallDist = (sideDistX - deltaDistX);
      else          perpWallDist = (sideDistY - deltaDistY);

      //Calculate height of line to draw on screen
      int lineHeight = (int)(h / perpWallDist);


      int pitch = 100;

      //calculate lowest and highest pixel to fill in current stripe
      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;

      //texturing calculations
      int texNum = worldMap[mapX][mapY] - 1; //1 subtracted from it so that texture 0 can be used!

      //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 coordinate 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;

      // TODO: 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++)
      {
        // Cast the texture coordinate to integer, and mask with (texHeight - 1) in case of overflow
        int texY = (int)texPos & (texHeight - 1);
        texPos += step;
        Uint32 color = texture[texNum][texHeight * texY + texX];
        //make color darker for y-sides: R, G and B byte each divided through two with a "shift" and an "and"
        if(side == 1) color = (color >> 1) & 8355711;
        buffer[y][x] = color;
      }
    }

    for(int y = 0; y < h; y++) for(int x = 0; x < w; x++) buffer[y][x] = 0; //clear the buffer instead of cls()
    drawBuffer(buffer[0]);

    //timing for input and FPS counter
    oldTime = time;
    time = getTicks();
    double frameTime = (time - oldTime) / 1000.0; //frametime is the time this frame has taken, in seconds
    print(1.0 / frameTime); //FPS counter
    redraw();

    //speed modifiers
    double moveSpeed = frameTime * 5.0; //the constant value is in squares/second
    double rotSpeed = frameTime * 3.0; //the constant value is in radians/second

    SDL_Event event;
    while(SDL_PollEvent(&event)) {
      if(event.type != SDL_KEYDOWN) continue;
      //move forward if no wall in front of you
      if(event.key.keysym.sym == SDLK_UP)
      {
        if(worldMap[int(posX + dirX * moveSpeed)][int(posY)] == false) posX += dirX * moveSpeed;
        if(worldMap[int(posX)][int(posY + dirY * moveSpeed)] == false) posY += dirY * moveSpeed;
      }
      //move backwards if no wall behind you
      if(event.key.keysym.sym == SDLK_DOWN)
      {
        if(worldMap[int(posX - dirX * moveSpeed)][int(posY)] == false) posX -= dirX * moveSpeed;
        if(worldMap[int(posX)][int(posY - dirY * moveSpeed)] == false) posY -= dirY * moveSpeed;
      }
      //rotate to the right
      if(event.key.keysym.sym == SDLK_RIGHT)
      {
        //both camera direction and camera plane must be rotated
        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);
      }
      //rotate to the left
      if(event.key.keysym.sym == SDLK_LEFT)
      {
        //both camera direction and camera plane must be rotated
        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);
      }
    }
  }

  return 0;
}