/*  Line.c    */

/* E. Angel, Interactive Computer Graphics */
/* A Top-Down Approach with OpenGL, Third Edition */
/* Addison-Wesley Longman, 2003 */
/* Updated:  Bary W Pollack, March, 2005 */

/* illustrates simple rubberband line drawing */

#include <GL/glut.h>

int  ww;
float  xm, ym, xmm, ymm;
int  first = 0;

void init (void)
{
    glClearColor (1.0, 1.0, 0.0, 1.0);
    glEnable (GL_COLOR_LOGIC_OP); 
    glLogicOp (GL_COPY);
}

void display (void)
{
    glClear (GL_COLOR_BUFFER_BIT);
    glColor3f (1.0, 0.0, 0.0);
    glRectf (0.25, 0.25, 0.75, 0.75);
    glLogicOp (GL_XOR);
    glColor3f (1.0, 1.0, 0.0);
    glFlush ();
}

void reshape (int w, int h)
{
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    gluOrtho2D (0.0,  1.0, 0.0,  1.0);
    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity ();
}

void mouse (int btn, int state, int x, int y)
{
    if (btn == GLUT_LEFT_BUTTON && state == GLUT_DOWN) 
    {
        switch (first)
        {
          case 0: 
            xm = x/500.;
            ym = (500-y)/500.;
            first = 1;
            break;
          case 1:
            xmm = x/500.0;
            ymm = (500-y)/500.0;
            glBegin (GL_LINES);
            glVertex2f (xm, ym);
            glVertex2f (xmm, ymm);
            glEnd ();
            glFlush ();
            first = 2;
            break;
          case 2:
            glBegin (GL_LINES);
            glVertex2f (xm, ym);
            glVertex2f (xmm, ymm);
            glEnd ();
            glFlush ();
            xmm = x/500.0;
            ymm = (500-y)/500.0;
            glBegin (GL_LINES);
            glVertex2f (xm, ym);
            glVertex2f (xmm, ymm);
            glEnd ();
            glFlush ();
            break;
        }
    }
    if (btn == GLUT_RIGHT_BUTTON && state == GLUT_DOWN) 
    {
        glLogicOp (GL_COPY);
        glColor3f (0.0, 0.0, 1.0);
        glBegin (GL_LINES);
        glVertex2f (xm, ym);
        glVertex2f (xmm, ymm);
        glEnd ();
        glFlush ();
        first = 0;
        glLogicOp (GL_XOR);
        glColor3f (0.0, 1.0, 0.0);
    }
}


int main (int argc, char** argv)
{
    /* Initialize mode and open a window in upper left corner of screen */
    glutInit (&argc, argv); 
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize (500, 500);
    glutInitWindowPosition (0, 0); 
    glutCreateWindow ("Rubberband");
    glutDisplayFunc (display);
    glutReshapeFunc (reshape);
    glutMouseFunc (mouse);
    init ();

    glutMainLoop ();

    return 0;
}