Copy3DEngine/src/moteur.c

// Voir README.md pour license précise, par Fcalva 2023-2024 et est sous GPLv3

#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include <gint/display.h>
#include <gint/keyboard.h>
#include <libprof.h>

#include "fixed.h"

#include "gint/display-cg.h"
#include "moteur.h"
#include "map.h"

// moteur.c :
// ici se trouvent tout ce qui concerne les graphismes, mouvement et collisions
//
//

void move() {
  extern int frame_time;
  fixed_t moveSpeed = fmul(fix(frame_time), 0x148); //frame_time * fix(carrés/seconde/1000) là carrés/seconde = 5
  fixed_t rotSpeed = fmul(fix(frame_time), 0x83); //frame_time * fix(radians/seconde/1000) là radians/seconde = 2
  fixed_t c_rotSpeed = fix(cos(f2float(rotSpeed)));
  fixed_t s_rotSpeed = fix(sin(f2float(rotSpeed)));

  extern char map_test[map_w][map_h];
  extern fixed_t planeX;
  extern fixed_t planeY;
  extern fixed_t dirX;
  extern fixed_t dirY;
  extern fixed_t posX;
  extern fixed_t posY;

  fixed_t oldDirX;
  fixed_t oldPlaneX;
  int xtemp1;
  int ytemp1;
  int xtemp2;
  int ytemp2;

  if (keydown(KEY_UP)) {
    xtemp1 = f2int(posX + fmul(dirX, moveSpeed) - 0xF);
    ytemp1 = f2int(posY);
    xtemp2 = f2int(posX);
    ytemp2 = f2int(posY + fmul(dirY, moveSpeed) - 0xF);

    if(map_test[xtemp1][ytemp1] == 0) posX += fmul(dirX, moveSpeed);
    if(map_test[xtemp2][ytemp2] == 0) posY += fmul(dirY, moveSpeed);
  }
  //move backwards if no wall behind you
  if (keydown(KEY_DOWN)) {
    xtemp1 = f2int(posX - fmul(dirX, moveSpeed) + 0xF);
    ytemp1 = f2int(posY);
    xtemp2 = f2int(posX);
    ytemp2 = f2int(posY - fmul(dirY, moveSpeed) + 0xF);

    if(map_test[xtemp1][ytemp1] == 0) posX -= fmul(dirX, moveSpeed);
    if(map_test[xtemp2][ytemp2] == 0) posY -= fmul(dirY, moveSpeed);
  }
  //rotate to the rightdouble sin_rotspeed;
  if (keydown(KEY_RIGHT)) {
    //both camera direction and camera plane must be rotated
    oldDirX = dirX;
    dirX = (fmul(dirX, c_rotSpeed)+1) - (fmul(dirY, -s_rotSpeed)+1); 
     dirY = (fmul(oldDirX, -s_rotSpeed)+1) + (fmul(dirY, c_rotSpeed)+1);
     oldPlaneX = planeX;
     planeX = (fmul(planeX, c_rotSpeed)+1) - (fmul(planeY, -s_rotSpeed)+1);
    planeY = (fmul(oldPlaneX, -s_rotSpeed)+1) + (fmul(planeY, c_rotSpeed)+1);
  }
  //rotate to the left
  if (keydown(KEY_LEFT)) {
    //both camera direction and camera plane must be rotated
    oldDirX = dirX;
    dirX = (fmul(dirX, c_rotSpeed)-1) - (fmul(dirY, s_rotSpeed)-1);
    dirY = (fmul(oldDirX, s_rotSpeed)+1) + (fmul(dirY, c_rotSpeed)+1);
    oldPlaneX = planeX;
    planeX = (fmul(planeX, c_rotSpeed)-1) - (fmul(planeY, s_rotSpeed) - 1);
    planeY = (fmul(oldPlaneX, s_rotSpeed)+1) + (fmul(planeY, c_rotSpeed) + 1);
  }

  if (dirX > 0xFFFF) dirX = 0xFFFF;
  if (dirY > 0xFFFF) dirY = 0xFFFF;
  if (dirX < -0xFFFF) dirX = -0xFFFF;
  if (dirY < -0xFFFF) dirY = -0xFFFF;
}

void spawn_gen(){
  extern fixed_t posX;
  extern fixed_t posY;
  extern fixed_t dirX;
  extern fixed_t dirY;
  extern fixed_t planeX;
  extern fixed_t planeY;
  extern char map_test[map_w][map_h];
  
  int seed, seed_x, seed_y;
  int SeedSeed;

  time_t timeN; 
  time(&timeN);
  SeedSeed = timeN;

  srand(SeedSeed);

  while(1){
    seed = rand() * 0.5 + rand() * 0.5;
    seed_x = seed & 0b1111111;
    seed_y = (seed >> 8) & 0b111111;
    if (seed_x < map_w && seed_y < map_h && (seed_x < 111 && seed_y > 15)){
      if(map_test[seed_x][seed_y] == 0){
        break;
      }
    }
  }
  fixed_t start_dirX, start_dirY;

  int dirSeed = (seed >> 9) & 0b11 ;
  switch(dirSeed){
    case 0: {
      start_dirX = 0x0;
      start_dirY = 0xFFFF;
      planeX = fix(0.66);
      planeY = 0;
      break;
    }
    case 1: {
      start_dirX = 0xFFFF;
      start_dirY = 0x0;
      planeX = 0;
      planeY = fix(-0.66);
      break;
    }
    case 2: {
      start_dirX = -0xFFFF;
      start_dirY = 0x0;
      planeX = 0;
      planeY = fix(0.66);
      break;
    }
    case 3: {
      start_dirX = 0x0;
      start_dirY = -0xFFFF;
      planeX = fix(-0.66);
      planeY = 0;
      break;
    }
    default : {
      start_dirX = 0xFFFF;
      start_dirY = 0x0;
      planeX = 0;
      planeY = fix(-0.66);
      break;
    }
  }

  posX = fix(seed_x) + 0x7FFF;
  posY = fix(seed_y) + 0x7FFF;  //x and y start position
  dirX = start_dirX;
  dirY = start_dirY; //initial direction vector
}

void load_map(){
  spawn_gen();
}

#if asm_opti
void draw_stripe(image_t *tex, int texSampleY, int linePos, fixed_t texSize, int texX, int x);
#else
void inline draw_stripe(image_t *tex, int texSampleY, int linePos, fixed_t texSize, int texX, int x){
    fixed_t screenPos = fix(linePos);
    uint32_t texDat = (uint32_t)tex->data + 2*texX;
    for(int texPos = texSampleY; texPos < 64; texPos++){
      if(screenPos < -texSize) goto noDraw;
      for(fixed_t oldPos = screenPos; oldPos < screenPos+texSize; oldPos+=0xFFFF){
        gint_vram[ffloor(oldPos)*396+x] = *(uint16_t*)texDat;
      }
      noDraw:
      screenPos += texSize;
      texDat += tex->stride;
    }
}
#endif

void draw_walls(){
    extern fixed_t posX;
    extern fixed_t posY;
    extern fixed_t dirX;
    extern fixed_t dirY;
    extern fixed_t planeX;
    extern fixed_t planeY;
    extern image_t *tex_index[TINDEX_S];
    extern char map_test[map_w][map_h];

    fixed_t cameraX;
    fixed_t rayDirX;
    fixed_t rayDirY;
    fixed_t sideDistX;//length of ray from current position to next x or y-side
    fixed_t sideDistY;
    fixed_t deltaDistX;
    fixed_t deltaDistY;
    fixed_t perpWallDist;
    fixed_t texSize;
    int x;
    int i;
    int mapX;
    int mapY;
    int stepX; //what direction to step in x or y-direction (either +1 or -1)
    int stepY;
    int side; //was a NS or a EW wall hit?
    int lineHeight;
    int texX;
    int texSample;
    int texSampleY;

    int v_offset = 0; //(int)(sin(f2int(posX + posY)) * 5); //a raffiner un peu
    fixed_t h_offset = 0; //fix(sin(f2int(posX - posY)) * 0.01);

    struct image_linear_map temp;

    for(x = 0; x < viewport_w; x++) {

      //calculate ray position and direction
      cameraX = fdiv(fix(x*2), fix(viewport_w)) - 0xFFFF + h_offset; //x-coordinate in camera space
      
      rayDirX = dirX + fmul(planeX, cameraX);
      rayDirY = dirY + fmul(planeY, cameraX);
      

      //which box of the map we're in
      mapX = f2int(posX);
      mapY = f2int(posY);

      // length of ray from one x or y-side to next x or y-side
      // these are derived as:
      // deltaDistX = sqrt(1 + (rayDirY * rayDirY) / (rayDirX * rayDirX))
      // deltaDistY = sqrt(1 + (rayDirX * rayDirX) / (rayDirY * rayDirY))
      // which can be simplified to abs(|rayDir| / rayDirX) and abs(|rayDir| / rayDirY)
      // where |rayDir| is the length of the vector (rayDirX, rayDirY). Its length,
      // unlike (dirX, dirY) is not 1, however this does not matter, only the
      // ratio between deltaDistX and deltaDistY matters, due to the way the DDA
      // stepping further below works. So the values can be computed as below.
      // Division through zero is prevented, even though technically that's not
      // needed in C++ with IEEE 754 floating point values. 

      rayDirX = rayDirX == 0 ? 1 : rayDirX;
      rayDirY = rayDirY == 0 ? 1 : rayDirY;

      deltaDistX = abs(fdiv(0xFFFF, rayDirX));
      deltaDistY = abs(fdiv(0xFFFF, rayDirY));

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

      if (rayDirY == 0) {
        stepY = 0;
        sideDistY = 0;
      }
      else if (rayDirY < 0) {
        stepY = -1;
        sideDistY = fmul(posY - fix(mapY), deltaDistY);
      }
      else {
        stepY = 1;
        sideDistY = fmul( fix(mapY + 1) - posY, deltaDistY);
      }
      //perform DDA
      while(true) {
        //Check if the ray is out of range/bounds
        if (sideDistX >= max_dist || sideDistY >= max_dist || mapX < 0 || mapY < 0 || mapX >= map_w || mapY >= map_h) {
          break;
        }
        //Otherwise check if ray has hit a wall
        else if (map_test[mapX][mapY] > 0) {
          break;
        }
        //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;
        }
      }
      //Calculate distance projected on camera direction. This is the shortest distance from the point where the wall is
      //hit to the camera plane. Euclidean to center camera point would give fisheye effect!
      //This can be computed as (mapX - posX + (1 - stepX) / 2) / rayDirX for side == 0, or same formula with Y
      //for size == 1, but can be simplified to the code below thanks to how sideDist and deltaDist are computed:
      //because they were left scaled to |rayDir|. sideDist is the entire length of the ray above after the multiple
      //steps, but we subtract deltaDist once because one step more into the wall was taken above.

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

      //texturing calculations

      //calculate value of wallX
      fixed_t wallX; //where exactly the wall was hit
      if (side == 0) wallX = posY + fmul(perpWallDist, rayDirY); 
      else  wallX = posX + fmul(perpWallDist, rayDirX);     
      wallX -= fix(floor(f2int(wallX)));

      //x coordinate on the texture
      texX = fmul(wallX, 64);
      texX = texX % 64;

      if(side == 0 && rayDirX > 0) texX = 64 - texX - 1;
      if(side == 1 && rayDirY < 0) texX = 64 - texX - 1;

      lineHeight = f2int(fdiv(fix(viewport_h), perpWallDist)); //Taille en px de la ligne
      if (lineHeight < 1) lineHeight = 1;
      //if (lineHeight > viewport_h) lineHeight = viewport_h - 1;

      fixed_t texSize = fix(lineHeight) / 64; //taille proportionelle de la ligne a la tex
      if (texSize < 0x400) texSize = 0x400; //0x400 = 1/64 * 2^16
      if (texSize > 0x3D000) { //0x3D000 = 3.8125 * 2^16, 3.8125 = viewport_h/64
        texSample = fceil(fdiv(fix(viewport_h), texSize));
        texSampleY  = 32 - texSample/2;
      }
      else {
        texSample = 64;
        texSampleY = 0; 
      }

      int linePos = viewport_h/2 - lineHeight/2;

      image_t *tex = tex_index[map_test[mapX][mapY]];

      draw_stripe(tex, texSampleY, linePos, texSize, texX, x);
  }
}