中望cad的pline命令画圆弧功能用c++代码表示

以下是使用C++代码实现中望CAD的Pline命令画圆弧功能的示例：

#include <iostream>
#include <cmath>

using namespace std;

// 定义圆弧结构体
struct Arc {
    double start_x;
    double start_y;
    double end_x;
    double end_y;
    double center_x;
    double center_y;
    double radius;
    double start_angle;
    double end_angle;
};

// 计算圆心坐标和半径
Arc calculateArc(double start_x, double start_y, double end_x, double end_y, double radius, int direction) {
    Arc arc;
    double d = sqrt(pow(end_x - start_x, 2) + pow(end_y - start_y, 2));
    double a = asin((end_y - start_y) / d);
    double b = acos((start_x - end_x) / (2 * radius));
    double c = direction * (a + b);

    arc.start_x = start_x;
    arc.start_y = start_y;
    arc.end_x = end_x;
    arc.end_y = end_y;
    arc.center_x = start_x + radius * sin(c);
    arc.center_y = start_y + radius * cos(c);
    arc.radius = radius;
    arc.start_angle = atan2(start_y - arc.center_y, start_x - arc.center_x);
    arc.end_angle = atan2(end_y - arc.center_y, end_x - arc.center_x);

    return arc;
}

int main() {
    // 模拟用户输入的起点、终点和半径
    double start_x = 0;
    double start_y = 0;
    double end_x = 5;
    double end_y = 5;
    double radius = 3;

    // 计算圆心坐标和半径
    Arc arc = calculateArc(start_x, start_y, end_x, end_y, radius, 1);

    // 输出圆心坐标和半径
    cout << "Center point: (" << arc.center_x << ", " << arc.center_y << ")" << endl;
    cout << "Radius: " << arc.radius << endl;

    return 0;
}

通过调用calculateArc函数来计算圆心坐标和半径，其中参数包括起点、终点、半径和方向（1表示逆时针，-1表示顺时针），返回值是一个包含圆心坐标和半径等信息的Arc结构体。在主函数中，我们模拟了用户输入的起点、终点和半径，然后调用calculateArc函数来计算圆心坐标和半径，并输出结果。注意，这里只是一个示例，实际应用中还需要考虑更多的因素。