broken ray cast code

gistfile1.txt

// adapting http://gamedev.stackexchange.com/a/49423/4129

  castRay: function(ray) {
		var	oX = ray[0][0], oY = ray[0][1], oZ = ray[0][2],
			dX = ray[1][0]-oX, dY = ray[1][1]-oY, dZ = ray[1][2]-oZ,
			x = Math.floor(oX), y = Math.floor(oY), z = Math.floor(oZ),
			intbound = function(s,ds) {
				if(ds < 0)
					return intbound(-s,-ds);
				return (1-((s%ds+ds)%ds))/ds;
			},
			tMaxX = intbound(oX,dX), tMaxY = intbound(oY,dY), tMaxZ = intbound(oZ,dZ),
			signum = function(x) { return x > 0 ? 1 : x < 0 ? -1 : 0; },
			stepX = signum(dX), stepY = signum(dY),stepZ = signum(dZ),
			tDeltaX = stepX/dX, tDeltaY = stepY/dY, tDeltaZ = stepZ/dZ,
			fX = 0, fY = 0, fZ = 0, ret, block;
		if(dX === 0 && dY === 0 && dZ === 0)
		  	throw new RangeError("Raycast in zero direction!");
		while ((stepX > 0? x < dX: x >= dX) &&
			(stepY > 0? y < dY: y >= dY) &&
			(stepZ > 0? z < dZ: z >= dZ)) {
			block = this.getBlock(x,y,z);
			if(block) {
				if(!ret)
					ret = [];
				ret.push([[x,y,z],block,[fX,fY,fZ]]);
			}
			if(tMaxX < tMaxY) {
				if(tMaxX < tMaxZ) {
					x += stepX;
					tMaxX += tDeltaX;
					fX = -stepX; fY = 0; fZ = 0;
				} else {
					z += stepZ;
					tMaxZ += tDeltaZ;
					fX = 0; fY = 0; fZ = -stepZ;
				}
			} else {
				if(tMaxY < tMaxZ) {
					y += stepY;
					tMaxY += tDeltaY;
					fX = 0; fY = -stepY; fZ = 0;
				} else {
					z += stepZ;
					tMaxZ += tDeltaZ;
					fX = 0; fY = 0; fZ = -stepZ;
				}
			}
		}
		return ret;
	},