Hey guys,
Im making a raycasting engine.
If you dont know what that is http://www.permadi.com/tutorial/raycast/index.html
This is an awesome tutorial i would recommend you read. However if you do know what im talking about im having a problem with making one.


It seems that the edges of my walls extend a bit farther than they should. creating a odd clipping effect on the cubes.

Heres the code.
Code:

int[][] wall = new int[300][300];
float[] ray = new float[641];
boolean[] keys = new boolean[4];
final int up = 0;
final int down = 1;
final int left = 2;
final int right = 3;


float px=50,py=200,pa;
float xa,ya,oldxa,oldya;
float xc,yc,rd;
int rn;
void setup(){

  size(640,400);
  smooth();
  wall[3][2]=1;
  wall[5][5]=1;
  wall[6][5]=1;
  wall[7][5]=1;
  wall[8][5]=1;
  wall[15][15]=1;
}




void draw(){
  noStroke();
  fill(255);
  rect(0,0,width,height/2);
  fill(50);
  rect(0,height/2,width,height/2);
  stroke(100);
  raydist();
  render();
  controls();

}

void raydist(){
  rn=0;
  for(float r=-PI/6;r<PI/6;r=r+(PI/3)/640){
    ray[rn]=-1;

    //HORIZ
    if(sin(pa+r)<0){
      ya=floor(py/64)*64-1;
      xc=64/tan(-(pa+r));
      yc=-64;
    }
    else{
      ya=floor(py/64)*64+64;
      xc=64/tan(pa+r);
      yc=64;
    }
    xa=px+((py-ya)/tan(-(pa+r)));
    oldxa=xa;
    oldya=ya;

    for(int i=0;i<6;i++){
      if(xa>0 &&xa<640){
        if(ya>0 &&ya<640){
          if(wall[floor(xa/64)][floor(ya/64)]==1){
            rd=sqrt(sq(xa-px)+sq(ya-py));
            if(ray[rn]==-1){
              ray[rn]=rd*cos(r);
            }
            else{
              if(rd<ray[rn]/cos(r)){
                ray[rn]=rd*cos(r);
              }
            }
          }
        }
      }
      xa=oldxa+xc;
      ya=oldya+yc;
      oldxa=xa;
      oldya=ya;
    }

    //VERT
    if(sin(pa+PI/2+r)<0){
      xa=floor(px/64)*64-1;
      yc=64*tan(-(pa+r));
      xc=-64;
    }
    else{
      xa=floor(px/64)*64+64;
      yc=64*tan(pa+r);
      xc=64;
    }
    ya=py+((px-xa)/tan(pa+PI/2+r));
    oldxa=xa;
    oldya=ya;

    for(int i=0;i<6;i++){
      if(xa>0 &&xa<640){
        if(ya>0 &&ya<640){
          if(wall[floor(xa/64)][floor(ya/64)]==1){
            rd=sqrt(sq(xa-px)+sq(ya-py));
            if(ray[rn]==-1){
              ray[rn]=rd*cos(r);
            }
            else{
              if(rd<ray[rn]/cos(r)){
                ray[rn]=rd*cos(r);
              }
            }
          }
        }
      }
      xa=oldxa+xc;
      ya=oldya+yc;
      oldxa=xa;
      oldya=ya;
    }
    rn++;
  }
}

void render(){
  for(int rn=0;rn<640;rn++){
    if(ray[rn]>0){
      float wh=64/ray[rn]*255;
      stroke(150);
      line(rn,height/2+wh,rn,height/2-wh);
    }
  } 
}


void controls(){
  if(keys[up]==true){
    px=px+cos(pa);
    py=py+sin(pa);

  }
  if(keys[down]==true){
    px=px-cos(pa);
    py=py-sin(pa);

  }
  if(keys[left]==true){
    pa-=.1;

  }
  if(keys[right]==true){
    pa+=.1;

  }




}

void keyPressed() {
  if (keyCode == UP) {
    keys[up] = true;
  }  
  else if(keyCode == DOWN) {
    keys[down] = true;
  } 

  else if(keyCode == LEFT) {
    keys[left] = true;
  } 
  else if (keyCode == RIGHT) {
    keys[right] = true;
  }
}

void keyReleased() {
  if (keyCode == UP) {
    keys[up] = false;
  }
  else if(keyCode == DOWN) {
    keys[down] = false;
  } 

  else if(keyCode == LEFT) {
    keys[left] = false;
  } 
  else if (keyCode == RIGHT) {
    keys[right] = false;
  }

}  

If anyone knows what im doing wrong it would be greatly appreciated.
Thanks in advance!
-Dev

I think it's those "-1"s.
e.g.
//HORIZ
ya=floor(py/64)*64-1;

and same in vert.

what are those meant to do?

Figured it out. It was the "-1"
It has to be a number close to zero such as .01.