图形的缩放

1.编码实现相对坐标原点的缩放变换(缩放比例由键盘输入)

2.相对任意一点的缩放变换(缩放的参考点由用户确定)

编译器：vs2013

// ConsoleApplication1.cpp : 定义控制台应用程序的入口点。
//

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

void zoom00(int a[],double sx,double sy);
void zoomxy(int a[], double sx, double sy,int x, int y);

int main()
{
    int gdriver = DETECT, gmove,i,x,y;
    double sx, sy;
    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:
");
    scanf_s("%lf%lf", &sx,&sy);

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

    drawpoly(14,a);

    zoom00(a, sx,sy);*/

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

    printf("Please input:
");
    scanf_s("%lf%lf", &sx, &sy);

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

    zoomxy(a, sx, sy,x, y);

    system("pause");

    closegraph();

    return 0;
}

//相对于原点缩放
void zoom00(int a[],double sx,double sy)
{
    int b[3][3] = { { sx, 0, 0 }, { 0, sy, 0 }, { 0, 0, 1 } }, c[28], i, j;

    for (i = 0; i < 28; i = i + 2)
    {
        c[i] = a[i] * sx;
        c[i + 1] = a[i + 1] * sy;
    }

    drawpoly(14, c);
}

//相对于任意一点缩放
void zoomxy(int a[], double sx, double sy,int x,int y)
{
    int b[3][3] = { { 1, 0, 0 }, { 0, 1, 0 }, { x,y ,1 } }, c[28], i, j;

    for (i = 0; i < 28; i = i + 2)
    {
        c[i] = a[i] - x;
        c[i + 1] = a[i + 1] - y;
        c[i] *= sx;
        c[i + 1] *= sy;
        c[i] += x;
        c[i+1] += y;
    }

    drawpoly(14, c);
}