旋转算法

一条直线通过端点绕一个半径为200的圆的圆心进行360度的旋转，在旋转的期间直线的端点一直在圆环上

#define _CRT_SECURE_NO_WARNINGS #include "graphics.h" #define _USE_MATH_DEFINES #include

struct Point { double x; double y;

1Point( void ) : x(), y()
2{
3}
4
5
6Point( double x, double y ) : x(x), y(y)
7{
8}
9
10
11Point translation( const Point& offset ) const // 平移
12{
13    return Point( x+offset.x, y+offset.y );
14}
15
16
17Point rotation( const Point& anchor, double angle ) const // 旋转
18{
19    double radian = fmod(angle,360) * M_PI/180;
20    return Point( cos(radian)*(x-anchor.x) - sin(radian)*(y-anchor.y) + anchor.x
21                , cos(radian)*(y-anchor.y) + sin(radian)*(x-anchor.x) + anchor.y );
22}
23
24
25Point scale( const Point& anchor, double ratio ) const // 缩放
26{
27    return Point( (x-anchor.x)*ratio+anchor.x, (y-anchor.y)*ratio+anchor.y );
28}

};

struct Line { Point a; Point b;

1Line( void )
2{
3}
4
5
6Line( const Point& a, const Point& b ) : a(a), b(b)
7{
8}
9
10
11Line translation( const Point& offset ) const // 平移
12{
13    return Line( a.translation(offset), b.translation(offset) );
14}
15
16
17Line rotation( const Point& anchor, double angle ) const // 旋转
18{
19    return Line( a.rotation(anchor,angle), b.rotation(anchor,angle) );
20}
21
22
23Line scale( const Point& anchor, double ratio ) const // 缩放
24{
25    return Line( a.scale(anchor,ratio), b.scale(anchor,ratio) );
26}
27
28
29void Draw( COLORREF color=WHITE, int style=PS_DOT, int thickness=1 ) const
30{
31    setlinecolor( color );
32    setlinestyle( style, thickness );
33    line( a.x, a.y, b.x, b.y );
34}

};

struct Circle { Point center; double radius;

1Circle( void ) : radius()
2{
3}
4
5
6Circle( const Point& center, double radius ) : center(center), radius(radius)
7{
8}
9
10
11void Draw( COLORREF color=WHITE, int style=PS_DOT, int thickness=1 ) const
12{
13    setlinecolor( color );
14    setlinestyle( style, thickness );
15    circle( center.x, center.y, radius );
16}

};

#include

int main( void ) { initgraph( 640, 480 );

1Circle( Point(320,240), 200 ).Draw( WHITE, PS_DOT, 2 );
2Line segment = Line( Point(320,40), Point(320,35) ).scale( Point(320,40), 10 );
3for( double angle=0; angle<360; angle+=1 )
4{
5    segment.rotation( Point(320,240), angle ).Draw( WHITE, PS_SOLID, 1 );
6}
7
8
9_getch();
10closegraph();

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