function drawRays3D() {
    let r,mx,my,mp,dof, rx,ry,ra,xo,yo, disT, mxfix=0,myfix=0, c="#F00";
    ra = pa-DR*30; 
    if (ra<0) { ra+=2*PI; } 
    if (ra>2*PI) { ra-=2*PI; }
    for (r=0;r<60;r++) {
        // --- Check Horizontal Lines ---
        dof=0;
        let disH = 999999, hx=px, hy=py;
        let aTan = -1/Math.tan(ra);
        if ( ra > PI ) { // looking up
            ry = (Math.floor(py/64)*64);    rx=(py-ry)*aTan+px; yo=-64; xo=-yo*aTan; myfix=-1;
        } 
        if ( ra < PI ) { // looking down
            ry = Math.ceil(py/64)*64; rx=(py-ry)*aTan+px; yo= 64; xo=-yo*aTan;
        } 
        if (ra === 0 || ra === PI) { // looking straight left or right
            rx=px; ry=py; dof=8;
        } 
        while (dof<8) {
            mx = Math.floor(rx / 64); 
            my = Math.round(ry / 64) + myfix;
            mp = my*mapX+mx;
            if (mp > 0 && mp<mapX*mapY && map[mp]===1) { hx=rx; hy=ry; disH=dist(px,py,hx,hy); dof = 8; } // hit wall
            else { rx+=xo; ry+=yo; dof+=1 } // next line
        }
        //Canvas.drawLine(px,py,rx,ry,"#00f");

        // --- Check Vertical Lines ---
        dof=0;
        let disV = 999999, vx=px, vy=py;
        let nTan = -Math.tan(ra);
        if ( ra > PI/2 && ra < 3*(PI/2) ) { // looking left
            rx = Math.floor(px/64)*64;  ry=(px-rx)*nTan+py; xo=-64; yo=-xo*nTan; mxfix=1;
        } 
        if ( ra < PI/2 || ra > 3*(PI/2) ) { // looking right
            console.log("right");
            rx = Math.ceil(px/64)*64;   ry=(px-rx)*nTan+py; xo= 64; yo=-xo*nTan;
        } 
        if (ra === 0 || ra === PI) { // looking straight up or down
            rx=px; ry=py; dof=8;
        } 
        while (dof<8) {
            mx = Math.round(rx / 64) - mxfix; 
            my = Math.floor(ry / 64);
            mp = my*mapX+mx;
            if (mp > 0 && mp<mapX*mapY && map[mp]===1) { vx=rx; vy=ry; disV=dist(px,py,vx,vy); dof = 8; } // hit wall
            else { rx+=xo; ry+=yo; dof+=1 } // next line
        }
        //Canvas.drawLine(px,py,rx,ry,"#f00");

        // check which ray hits closer and use that rays coords
        if(disV<disH) { rx=vx; ry=vy; disT=disV; c="#F00"}
        if(disH<disV) { rx=hx; ry=hy; disT=disH; c="#C00"}

        // draw 2d ray
        Canvas.drawLine(px,py,rx,ry,"#0F0");

        // --- Draw 3D Walls ---
        let ca = pa-ra; (ca<0); { ca+=2*PI; } if (ca>2*PI) { ca-=2*PI; } 
        disT=disT*Math.cos(ca); // fix fisheye
        let lineH = (mapS*320)/disT;
        if (lineH>320) { lineH=320; }
        let lineO = 160 - lineH/2;
        //Canvas.drawLine(r*8+530,0,r*8+530,0,c,8);
        Canvas.drawSquare(r*8+530,lineO,8,lineH,c);

        // next ray angle
        ra += DR; if (ra<0) { ra+=2*PI; } if (ra>2*PI) { ra-=2*PI; }
    }
}