图形的旋转

1.编码实现绕原点的旋转变换(旋转角度由键盘输入),

2.绕任意一点的旋转变换(由键盘输入旋转角度和旋转中心)

编译器：vs2013 

#include "stdafx.h"
#include<stdio.h>
#include"graphics.h"
#include<stdlib.h>
#include<math.h>

#define PI 3.14159

void spin00(int a[], double angle);
void spinxy(int a[], double angle, int x, int y);

int main()
{
    int gdriver=DETECT, gmove;
    double angle;
    int a[28] = { 100, 100, 150, 150, 250, 150, 250, 0, 350, 150, 450, 150, 500, 200, 450, 250, 350, 250, 250, 400, 250, 250, 150, 250, 100, 300, 100, 100 };

    /*printf("please input the angle:
");
    scanf_s("%lf", &angle);

    initgraph(&gdriver, &gmove, "");

    drawpoly(14, a);

    spin00(a, angle);*/

    int x, y;

    printf("please input the angle:
");
    scanf_s("%lf", &angle);
    printf("please input the point:
");
    scanf_s("%d%d", &x, &y);

    initgraph(&gdriver, &gmove, "");

    spinxy(a, angle, x, y);

    system("pause");

    closegraph();

    return 0;
}

//绕原点旋转变换
void spin00(int a[], double angle)
{
    int i,b[28];

    for (i = 0; i < 28; i = i + 2)
    {
        b[i] = a[i] * cos(angle / 180.0*PI) - a[i + 1] * sin(angle / 180.0*PI);
        b[i + 1] = a[i] * sin(angle / 180.0*PI) + a[i + 1] * cos(angle / 180.0*PI);
    }

    drawpoly(14, b);
}

//绕（x，y）旋转变换
void spinxy(int a[], double angle, int x, int y)
{
    int i, b[28],t;

    for (i = 0; i < 28; i = i + 2)
    {
        b[i] = a[i] - x;
        b[i + 1] = a[i + 1] - y;
        t = b[i];
        b[i] = b[i] * cos(angle / 180.0*PI) - b[i + 1] * sin(angle / 180.0*PI);
        b[i + 1] = t * sin(angle / 180.0*PI) + b[i + 1] * cos(angle / 180.0*PI);
        b[i] = b[i] + x;
        b[i + 1] = b[i + 1] + y;
    }

    drawpoly(14, b);
}

小结：在第二题时需要注意b[i]在操作过程中被改变，需要设置新变量来存储旧值