/*** 计算出线在屏幕内的最长坐标* x1, y1 = 坐标1, x2, y2 = 坐标2*/private createAimLinePosArr(x1: number, y1: number, x2: number, y2: number) {    let posX, posY;    if (y2 == y1) y1 += 0.01    if (x2 == x1) x1 += 0.01    if (y2 < y1) {        if (x2 < x1) {            posX = 0            posY = this.binaryEquationGetY(x1, y1, x2, y2, posX)        } else {            posX = Const.STAGE_WIDTH //最大屏幕宽度            posY = this.binaryEquationGetY(x1, y1, x2, y2, posX)        }    } else if (y2 > y1) {        if (x2 > x1) {            posX = Const.STAGE_WIDTH //最大屏幕宽度            posY = this.binaryEquationGetY(x1, y1, x2, y2, posX)        } else {            posX = 0            posY = this.binaryEquationGetY(x1, y1, x2, y2, posX)        }    }    if (posY < Const.STAGE_HEIGHT) {        if (posY <= 0) {            posY = 0            posX = this.binaryEquationGetX(x1, y1, x2, y2, posY)        }        return [posX, posY]    } else {        posY = Const.STAGE_HEIGHT //最大屏幕高度        posX = this.binaryEquationGetX(x1, y1, x2, y2, posY)        if (isNaN(posX)) {            if (x2 > x1) {                posX = Const.STAGE_WIDTH            } else {                posX = 0            }            console.log("posX == NaN", x1, y1, x2, y2, posY)        }        return [posX, posY]    }}

 

/** * 二元一次方程：根据x求y */public binaryEquationGetY(x1, y1, x2, y2, x) {    let kbArr = this.binaryEquationGetKB(x1, y1, x2, y2)    let k = kbArr[0]    let b = kbArr[1]    return k * x + b}

 

/** * 二元一次方程：根据y求x */public binaryEquationGetX(x1, y1, x2, y2, y) {    let kbArr = this.binaryEquationGetKB(x1, y1, x2, y2)    let k = kbArr[0]    let b = kbArr[1]    return (y - b) / k}

 

/** * 求二元一次方程的系数 * y1 = k * x1 + b => k = (y1 - b) / x1 * y2 = k * x2 + b => y2 = ((y1 - b) / x1) * x2 + b */private binaryEquationGetKB(x1, y1, x2, y2) {    let k = (y1 - y2) / (x1 - x2)    let b = (x1 * y2 - x2 * y1) / (x1 - x2)    return [k, b]}