Question

https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection#Given_two_points_on_each_line

https://www.youtube.com/watch?v=TOEi6T2mtHo

我尝试在代码中实现此方法，但无济于事，我相信问题是pygame中的y轴倒置还是我看不见其他东西？有什么建议么？

这是我的代码：

        x1 = other.pos1[0]
        y1 = other.pos1[1]
        x2 = other.pos2[0]
        y2 = other.pos2[1]

        x3 = self.pos1[0]
        y3 = self.pos1[1]
        x4 = self.pos2[0]
        y4 = self.pos2[1]

        den = (x1 - x2) * (y3 - y4) - (y1 * y2 * (x3 - x4))

        if den == 0:
            return

        t = ((x1 - x3) * (y3 - y4) - (y1 - y3) * (x3 - x4)) / den

        u = -(((x1 - x2) * (y1 - y3) - (y1 - y2) * (x1 - x3))) / den

        if t > 0 and t < 1 and u > 0:
            point = (x3 + u * (x4 - x3), y3 + u * (y4 - y3))

            pygame.gfxdraw.filled_circle(surface, point[0], point[1], 3, (255, 0, 0))

            return point

        else:
            return

Answer 1

Line–line intersection的分母由以下公式计算：

(x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4).

因此以下表达式是错误的：

den = (x1 - x2) * (y3 - y4) - (y1 * y2 * (x3 - x4))

必须为：

den = (x1-x2)*(y3-y4) - (y1-y2)*(x3-x4))

线对线与pygame的倒置y轴相交

1 个答案: