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rays.js
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rays.js
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(function (Ω) {
"use strict";
var rays = {
cast: function (angle, originX, originY, map) {
angle %= Math.PI * 2;
if (angle < 0) angle += Math.PI * 2;
var twoPi = Math.PI * 2,
ox = originX / map.sheet.w,
oy = originY / map.sheet.h,
right = angle > twoPi * 0.75 || angle < twoPi * 0.25,
up = angle > Math.PI,
sin = Math.sin(angle),
cos = Math.cos(angle),
dist = null,
distVertical = 0,
distX,
distY,
xHit = 0,
yHit = 0,
cell = 0,
wallX,
wallY,
slope = sin / cos,
dx = right ? 1 : -1,
dy = dx * slope,
x = right ? Math.ceil(ox) : Math.floor(ox),
y = oy + (x - ox) * slope;
while (x >= 0 && x < map.cellW && y >=0 && y < map.cellH) {
wallX = Math.floor(x + (right ? 0 : -1));
wallY = Math.floor(y);
cell = map.cells[wallY][wallX];
if (cell > 0) {
distX = x - ox;
distY = y - oy;
dist = Math.sqrt(distX * distX + distY * distY);
xHit = x;
yHit = y;
break;
}
x += dx;
y += dy;
}
// Check vertical walls
slope = cos / sin;
dy = up ? -1 : 1;
dx = dy * slope;
y = up ? Math.floor(oy) : Math.ceil(oy);
x = ox + (y - oy) * slope;
while (x >= 0 && x < map.cellW && y >=0 && y < map.cellH) {
wallY = Math.floor(y + (up ? -1 : 0));
wallX = Math.floor(x);
cell = wallY < 0 ? null : map.cells[wallY][wallX];
if (cell) {
distX = x - ox;
distY = y - oy;
distVertical = Math.sqrt(distX * distX + distY * distY);
if (dist === null || distVertical < dist) {
dist = distVertical;
xHit = x;
yHit = y;
}
break;
}
x += dx;
y += dy;
}
if (dist) {
return {
x: xHit,
y: yHit
};
} else {
return null;
}
},
render: function (gfx, ox, oy, rayX, rayY, map) {
var c = gfx.ctx;
c.strokeStyle = "rgba(100,0,0,0.2)";
c.lineWidth = 0.5;
c.beginPath();
c.moveTo(ox, oy);
c.lineTo(rayX * map.sheet.w, rayY * map.sheet.h);
c.closePath();
c.stroke();
}
};
Ω.rays = rays;
}(window.Ω));