例程1
#include <graphics.h>
#include "AFFINE.C"
main()
{
int driver=DETECT,mode;
static double x1[]={0.0,10.0,100.0,110.0,0.0};
static double y1[]={0.0,50.0,50.0,-10.0,0.0};
static double x2[5],y2[5];
int i;
double x,xx,yy;
initgraph(&driver,&mode," ");
axis();
for (x=-300;x<=200;x=x+10)
{
parallel(x,x/2);
for (i=0;i<=4;i++)
{
x2[i]=affinex(x1[i],y1[i],1.0);
y2[i]=affiney(x1[i],y1[i],1.0)/2;
}
for (i=0;i<=3;i++)
{
line(scx(x2[i]),scy(y2[i]),scx(x2[i+1]),scy(y2[i+1]));
}
}
getch();
closegraph();
}
例程2
#include <graphics.h>
#include "affine.c"
main()
{
int graphdriver=DETECT,graphmode;
static double x1[]={0.0,10.0,100.0,110.0,0.0};
static double y1[]={0.0,50.0,50.0,0.0,0.0};
static double x2[5],y2[5];
int i;
double r,xx,yy;
initgraph(&graphdriver,&graphmode,"");
for (r=0;r<=360;r+=10)
{
rotate(r);
for (i=0;i<=4;i++)
{
x2[i]=affinex(x1[i],y1[i],1.0);
y2[i]=affiney(x1[i],y1[i],1.0)/2;
}
for (i=0;i<=3;i++)
{
line(scx(x2[i]),scy(y2[i]),scx(x2[i+1]),scy(y2[i+1]));
}
}
getch();
closegraph();
}
例程3
#include <graphics.h>
#include <math.h>
#include "affine.c"
main()
{
int driver=DETECT,mode;
static double x1[]={-20.0,0.0,30.0,10.0,-20.0};
static double y1[]={0.0,17.0,-10.0,-20.0,0.0};
static double x2[5],y2[5];
int i;
double r;
initgraph(&driver,&mode,"");
axis();
for (r=0;r<=360;r+=10)
{
rotate(r);
for (i=0;i<=4;i++)
{
x2[i]=affinex(x1[i],y1[i],1.0);
y2[i]=affiney(x1[i],y1[i],1.0);
}
parallel(cos(r/180*3.1415926)*150.0,sin(r/180*3.1415926)*100.0);
for (i=0;i<=4;i++)
{
x2[i]=affinex(x2[i],y2[i],1.0);
y2[i]=affiney(x2[i],y2[i],1.0);
line(scx(x2[i]),scy(y2[i]),scx(x2[i+1]),scy(y2[i+1]));
}
for (i=0;i<=3;i++)
{
line(scx(x2[i]),scy(y2[i]),scx(x2[i+1]),scy(y2[i+1]));
}
}
getch();
closegraph();
}
其中用到的affine.c
double sin(),cos();
double xmax=639.0,ymax=399.0;
double f[3][3],xx,yy;
scx(xj) //将实际的x坐标转换为屏幕坐标
double xj;
{
int x;
x=(int)(xj+xmax/2);
return x;
}
scy(yi) //将实际的y坐标转换为屏幕坐标
double yi;
{
int y;
y=ymax-(int)(yi+(ymax/2));
return y;
}
parallel(dx,dy) //完成平移变换，dx,dy分别为x轴方向和y轴方向的平移量
double dx,dy;
{
f[0][0]=1.0; f[0][1]=0.0; f[0][2]=0.0;
f[1][0]=0.0; f[0][1]=1.0; f[1][2]=0.0;
f[2][0]=dx; f[2][1]=dy; f[2][2]=1.0;
}
rotate(theta) //以原点为中心的旋转变换，旋转角度为theta
double theta;
{
double th;
th=theta/180*3.1415926;
f[0][0]=cos(th); f[0][1]=sin(th);
f[0][2]=0.0; f[1][0]=-sin(th);
f[1][1]=cos(th); f[1][2]=0.0;
f[2][0]=0.0; f[2][1]=0.0; f[2][2]=1.0;
}
scale(s)
double s; //比例变换，比例系数为s
{
f[0][0]=s; f[0][1]=0.0; f[0][2]=0.0;
f[1][0]=0.0; f[1][1]=s; f[1][2]=0.0;
f[2][0]=0.0; f[2][1]=0.0; f[2][2]=1.0;
}
taisho_x() //对称变换,对称轴为x
{
f[0][0]=1.0; f[0][1]=0.0; f[0][2]=0.0;
f[1][0]=0.0; f[1][1]=-1.0; f[1][2]=0.0;
f[2][0]=0.0; f[2][1]=0.0; f[2][2]=1.0;
}
taisho_y() //对称变换,对称轴为y
{
f[0][0]=-1.0; f[0][1]=0.0; f[0][2]=0.0;
f[1][0]=0.0; f[1][1]=-1.0; f[1][2]=0.0;
f[2][0]=0.0; f[2][1]=0.0; f[2][2]=1.0;
}
taisho_o() //对称变换,对称轴为原点
{
f[0][0]=-1.0; f[0][1]=1.0; f[0][2]=0.0;
f[1][0]=0.0; f[1][1]=-1.0; f[1][2]=0.0;
f[2][0]=0.0; f[2][1]=0.0; f[2][2]=1.0;
}
taisho_xy() //对称变换,对称轴为x=y
{
f[0][0]=0.0; f[0][1]=1.0; f[0][2]=0.0;
f[1][0]=1.0; f[1][1]=0.0; f[1][2]=0.0;
f[2][0]=0.0; f[2][1]=0.0; f[2][2]=1.0;
}
taishl(aa,bb,cc) //对称变换,对称轴为任意直线
{
float y,p;
y=bb*bb-aa*aa;
p=aa*aa+bb*bb;
f[0][0]=-y/p; f[0][1]=-2*aa*bb/p; f[0][2]=0.0;
f[1][0]=-2*aa*bb/p; f[1][1]=-y/p; f[1][2]=0.0;
f[2][0]=-2*aa*cc/p; f[2][1]=-2*bb*cc/p; f[2][2]=1.0;
}
axis() //坐标变换为屏幕中心为原点，座和上分别为x轴和y轴的正方向
{
line(scx(0),scy(-ymax/2),scx(0),scy(ymax/2));
line(scx(-xmax),scy(0,0),scx(xmax/2),scy(0.0));
}
tuoq(a,b)
double a,b;
{
f[0][0]=1.0; f[0][1]=b; f[0][2]=0.0;
f[1][0]=a; f[1][1]=1.0; f[1][2]=0.0;
f[2][0]=0.0; f[2][1]=0.0; f[2][2]=1.0;
}
affinex(x,y,d)
double x,y,d;
{
xx=x*f[0][0]+y*f[1][0]+d*f[2][0];
return(xx);
}
affiney(x,y,d) //图形元素与矩阵元素相乘
double x,y,d;
{
yy=x*f[0][1]+y*f[1][1]+d*f[2][1];
return(yy);
}
