确定两个点是否在javascript中在线的同一侧

var A = [ { x: 385, y: 380 }, { x: 420, y: 400 }]

var B = { x: 385, y: 420 }
var C = { x: 405, y: 423 }

var TILE_WIDTH = 70
var TILE_HEIGHT = 80

function Hexagon(x, y) {
    var normalColor = \'rgb(207, 226, 243)\'
    var hilightColor = \'rgb(204, 204, 204)\'
    var currentColor = normalColor

    var coords = new TileCoordinates(x, y)
    var points = [
        { x: coords.x, y: coords.y - TILE_HEIGHT / 2 },
        { x: coords.x + TILE_WIDTH / 2, y: coords.y - TILE_HEIGHT / 4 },
        { x: coords.x + TILE_WIDTH / 2, y: coords.y + TILE_HEIGHT / 4 },
        { x: coords.x, y: coords.y + TILE_HEIGHT / 2 },
        { x: coords.x - TILE_WIDTH / 2, y: coords.y + TILE_HEIGHT / 4 },
        { x: coords.x - TILE_WIDTH / 2, y: coords.y - TILE_HEIGHT / 4 },
    ]

    var sides = [
        [points[0], points[1]],
        [points[1], points[2]],
        [points[2], points[3]],
        [points[3], points[4]],
        [points[4], points[5]],
        [points[5], points[0]]
    ]

    this.update = function (totalTime, updateTime) {

        var B = coords
        var C = Mouse.state
        var inside = C != null
        if (inside) {
            for (i in sides) {
                var A = sides[i]
                var w = { y: A[1].x - A[0].x, x: -(A[1].y - A[0].y) }
                var P = A[1]

                inside = ((B.x - P.x) * w.x + (B.y - P.y) * w.y) * ((C.x - P.x) * w.x + (C.y - P.y) * w.y) > 0
                if (!inside) break
            }
        }

        if (inside)
            currentColor = hilightColor
        else
            currentColor = normalColor
    }

    this.draw = function (ctx) {
        ctx.fillStyle = currentColor
        ctx.strokeStyle = \'rgb(11, 83, 148)\'
        ctx.beginPath()
        ctx.moveTo(points[0].x, points[0].y)
        ctx.lineTo(points[1].x, points[1].y)
        ctx.lineTo(points[2].x, points[2].y)
        ctx.lineTo(points[3].x, points[3].y)
        ctx.lineTo(points[4].x, points[4].y)
        ctx.lineTo(points[5].x, points[5].y)
        ctx.lineTo(points[0].x, points[0].y)
        ctx.fill()
        ctx.stroke()

        ctx.fillStyle = \'#000\'
        var text = coords.pos_x + \',\' + coords.pos_y
        var measure = ctx.measureText(text)
        ctx.fillText(text, coords.x - measure.width / 2, coords.y + 12 + (TILE_HEIGHT / 4))
    }
}

// this is in a separate function because other objects that render into the hex
// need the pixel coordinates of the tile also
function TileCoordinates(x, y) {
    this.pos_x = x
    this.pos_y = y
    this.x = x * TILE_WIDTH + ((y + 1) * TILE_WIDTH / 2)
    this.y = (y + 1) * (3 / 4 * TILE_HEIGHT)
}