GLUT Motion Func Callback....

Hi All,

PF the code below that demonstrates the use of glutMotionFunc() callback function.

Analyze this code and mail back to us for any queries.

You can post your queries here.

Thanks,

Govind N. & Vishal K.

#include <GL/glut.h>
#include <stdlib.h>

GLsizei wh = 500, ww = 500; /* initial window size */
GLfloat size = 10.0;   /* half side length of square */

void drawSquare(int x, int y)
{

   y=wh-y;
   glColor3ub( (char) rand()%256, (char) rand()%256, (char) rand()%256);
   glBegin(GL_POLYGON);
      glVertex2f(x+size, y+size);
      glVertex2f(x-size, y+size);
      glVertex2f(x-size, y-size);
      glVertex2f(x+size, y-size);
   glEnd();
   glFlush();
}

/* rehaping routine called whenever window is resized
or moved */

void myReshape(GLsizei w, GLsizei h)
{

/* adjust clipping box */

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, (GLdouble)w, 0.0, (GLdouble)h, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

/* adjust viewport and clear */

    glViewport(0,0,w,h);
    glClearColor (0.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glFlush();

/* set global size for use by drawing routine */

    ww = w;
    wh = h;
}

void myinit(void)
{

    glViewport(0,0,ww,wh);

/* Pick 2D clipping window to match size of screen window
This choice avoids having to scale object coordinates
each time window is resized */

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, (GLdouble) ww , 0.0, (GLdouble) wh , -1.0, 1.0);

/* set clear color to black and clear window */

    glClearColor (0.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    glFlush();

/* callback routine for reshape event */

    glutReshapeFunc(myReshape);

}

void mouse(int btn, int state, int x, int y)
{
    if(btn==GLUT_RIGHT_BUTTON && state==GLUT_DOWN)   exit(0);
}

/* display callback required by GLUT 3.0 */

void display(void)
{}

int main(int argc, char** argv)
{

    glutInit(&argc,argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
    glutCreateWindow("square");
    myinit ();
    glutReshapeFunc (myReshape);
    glutMouseFunc (mouse);
    glutMotionFunc(drawSquare);
    glutDisplayFunc(display);

    glutMainLoop();

}