드래그하면서 점선으로 된 사각형 그리기

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#include <windows.h> #include <iostream.h> #include <math.h> #include <gl/gl.h> #include <gl/glut.h> // (or others, depending on the system in use)   #define     PI              3.1415926 #define     Window_Width    400 #define     Window_Height   400 #define     DOT             0 #define     RUBBER          1 #define     SOLID           2   int         position_x = 0; int         position_y = 0; int         width,  height; int         point[1000][2]; int         num = 0;   struct Point {     float   x;     float   y; }; Point   left_down, right_up; Point   start_point, end_point;   int     draw_type; int     redraw;   void init (void) // 초기화설정, 상수값 설정 {     glClearColor (1.0, 1.0, 1.0, 0.0) ; // Set display-window color to white.     glMatrixMode (GL_PROJECTION); // Set projection parameters.     gluOrtho2D (-200, 200, -200, 200); // 관측공간 설정     width = Window_Width;     height = Window_Height;     draw_type = DOT; // 점선이냐 실선이냐     redraw = 0; }   void MyReshape(int w, int h) {     glViewport(position_x, position_y, w, h);     glMatrixMode(GL_PROJECTION);     glLoadIdentity();     gluOrtho2D (-200, 200, -200, 200);     glMatrixMode(GL_MODELVIEW);     glLoadIdentity(); }     void Draw_Rectangle(void) //사각형 그리기 {           if (draw_type == RUBBER)     {         glEnable(GL_LINE_STIPPLE);         glLineStipple(1, 0x0101); // 점선의 모양 결정         // 0x0101 은 16진수 숫자로써 점선의 패턴을 만들어내는 코드 이다         glBegin(GL_LINE_LOOP);         glVertex2f(left_down.x, left_down.y);         glVertex2f(right_up.x, left_down.y);         glVertex2f(right_up.x, right_up.y);         glVertex2f(left_down.x, right_up.y);         glEnd();     }               else if ( draw_type == SOLID)     {         glDisable(GL_LINE_STIPPLE);         glRectf(left_down.x, left_down.y, right_up.x, right_up.y);     }; }     void RenderScene (void) // 전체적인 그림 그리기  {     glClear (GL_COLOR_BUFFER_BIT);           glDisable(GL_LINE_STIPPLE);     glBegin (GL_LINES);     glColor3f(1.0, 0.0, 0.0);     glVertex2f (-200, 0);     glVertex2f ( 200, 0);           glColor3f(0.0, 0.0, 1.0);     glVertex2f (0, -200);     glVertex2f (0, 200);     glEnd();           Draw_Rectangle();                 glFlush ();     glutSwapBuffers(); }   void Check_Position(void) // 마우스좌표 {     if ( start_point.x <= end_point.x )     {         if ( start_point.y <= end_point.y )         {             left_down.x =   start_point.x;             left_down.y =   start_point.y;             right_up.x =    end_point.x;             right_up.y =    end_point.y;         }         else {             left_down.x =   start_point.x;             left_down.y =   end_point.y;             right_up.x =    end_point.x;             right_up.y =    start_point.y;         }     }     else {         if ( start_point.y <= end_point.y )         {             left_down.x =   end_point.x;             left_down.y =   start_point.y;             right_up.x =    start_point.x;             right_up.y =    end_point.y;         }         else         {             left_down.x =   end_point.x;             left_down.y =   end_point.y;             right_up.x =    start_point.x;             right_up.y =    start_point.y;         }     } }   void mouse( int button, int state, int x, int y) // 마우스 왼쪽버튼과 오른쪽 실행시  {     if ( draw_type == DOT && button == GLUT_LEFT_BUTTON && state == GLUT_DOWN )     {         start_point.x = x - Window_Width/2;         start_point.y = Window_Height/2 - y;         draw_type = RUBBER; // 사각형 그리기 시작         if ( redraw == 1 )         {             end_point.x = start_point.x;             end_point.y = start_point.y;             redraw = 0;             Check_Position();         }     }     if ( draw_type == RUBBER && button == GLUT_LEFT_BUTTON && state == GLUT_UP )     {         draw_type = SOLID; // 왼쪽버튼을 눌리다가 때어버리면 왼쪽버튼은 쓸모가 없는 이벤트가 되어 버린다         end_point.x = x - Window_Width/2;         end_point.y = Window_Height/2 - y;     }     if ( draw_type == SOLID && button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN )     {         draw_type = DOT; // 오른쪽 버튼 눌리면 제일처음 상태로 돌아간다 (사각형이 지워진다)         redraw = 1;     }     glutPostRedisplay();     RenderScene(); }   void MyKey (unsigned char key, int x, int y) // 창을 키웠을시에 6번을 누르게 되면 좌표가 작아 지게 됨  {     switch( key )     {     case '6' :  position_x = 0;         position_y = 0;         width = Window_Width;         height = Window_Height;         break;     }     glViewport(position_x, position_y, width, height);     glutPostRedisplay(); }         void MyMotion(int x, int y) // 마우스의 움직임을 찾는다, 왼쪽버튼을 눌렀을때 진행되는 함수  {     if ( draw_type == RUBBER )     {         end_point.x = x - Window_Width/2;         end_point.y = Window_Height/2 - y;     }     Check_Position();     glutPostRedisplay(); }     void main (int argc, char** argv) {     glutInit (&argc, argv);     glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);     glutInitWindowPosition(100, 100);     glutInitWindowSize(Window_Width, Window_Height);     glutCreateWindow ("Motion_Event");     init();     glutDisplayFunc (RenderScene);     glutMotionFunc(MyMotion);     glutReshapeFunc(MyReshape);     glutKeyboardFunc(MyKey);     glutMouseFunc(mouse);     glutMainLoop(); } ;