#include <GL/glut.h>
/* globals */
GLsizei wh = 500, ww = 500; /* initial window size */
GLfloat size = 3.0; /* half side length of square */
void drawSquare(int x, int y)
{
y=wh-y;
glColor3ub( (char) random()%256, (char) random()%256, (char) random()%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();
}