/* October 2001
 * Brian J.Ross
 * Brock University, Dept of Computer Science
 * COSC 3P98 Midterm solution A
 *
 * This solution uses mode flags within a single drawing/idle func callback
 * to either draw triangles, rectangles, or nothing (freeze mode).
 */

#if !defined(Linux)
  #include <windows.h>           //Not Linux must be windows
#endif
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <stdlib.h>

#define FALSE 0
#define TRUE 1
#define TRIANGLE 0
#define RECTANGLE 1

#define MINDIM 0
#define MAXDIM 500
#define MYRANDOM ((float) rand()/RAND_MAX)

struct glob {
   int mode;
   int freeze;
};
struct glob global = {TRIANGLE, FALSE};

void keybd(unsigned char key, int x, int y) {

	switch (key) {

		case 't':
		case 'T':
		   global.mode = TRIANGLE;
		   global.freeze = FALSE;
		   break;

		case 's':
		case 'S':
		   global.mode = RECTANGLE;
		   global.freeze = FALSE;
		   break;

		case 'f':
		case 'F':
		   global.freeze = !global.freeze;
		   break;

		case 'r':
		case 'R':
		   glClear(GL_COLOR_BUFFER_BIT);
		   glFlush();
		   break;

		case 'q':
		case 'Q':
		   exit(0);
		   break;
	}
}

void  draw(void) { 
	int x1, y1, x2, y2;

	if (global.freeze)
	   return;

	switch (global.mode) {

		case TRIANGLE:  
		   glColor3f(MYRANDOM, MYRANDOM, MYRANDOM);
		   glBegin(GL_POLYGON);
		     glVertex2i((int)(MYRANDOM*MAXDIM), (int)(MYRANDOM*MAXDIM));
		     glVertex2i((int)(MYRANDOM*MAXDIM), (int)(MYRANDOM*MAXDIM));
		     glVertex2i((int)(MYRANDOM*MAXDIM), (int)(MYRANDOM*MAXDIM));
		   glEnd();
		   glFlush();
		   break;

		case RECTANGLE:  
		   x1 = (int) (MYRANDOM * MAXDIM);
		   y1 = (int) (MYRANDOM * MAXDIM);
		   x2 = (int) (MYRANDOM * MAXDIM);
		   y2 = (int) (MYRANDOM * MAXDIM);
		   glBegin(GL_POLYGON);
		   	glColor3f(MYRANDOM, MYRANDOM, MYRANDOM);
			glVertex2i(x1, y1);
		   	glColor3f(MYRANDOM, MYRANDOM, MYRANDOM);
			glVertex2i(x2, y1);
		   	glColor3f(MYRANDOM, MYRANDOM, MYRANDOM);
			glVertex2i(x2, y2);
		   	glColor3f(MYRANDOM, MYRANDOM, MYRANDOM);
			glVertex2i(x1, y2);
		   glEnd();
		   glFlush();
		   break;
	}
}

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

	glutInit(&argc, argv);
	glutInitWindowSize(MAXDIM, MAXDIM);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutCreateWindow("window");

	glutDisplayFunc(draw);
	glutIdleFunc(draw);
	glutKeyboardFunc(keybd);

	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(MINDIM, MAXDIM, MINDIM, MAXDIM);
	glClearColor (1.0, 1.0, 1.0, 1.0);

	glutMainLoop();
	return 0;
}