/* October 2001
 * Brian J.Ross
 * Brock University, Dept of Computer Science
 * COSC 3P98 Midterm solution B
 *
 * This solution resets the IdleFunc callback according to one of
 * 3 modes: triangle, rectangle, or freeze. 
 */

#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 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  clearwin(void) { 

	glClear(GL_COLOR_BUFFER_BIT);
	glFlush();
}

void  triangle(void) { 

	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();
}

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

	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();
}

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

	switch (key) {

		case 't':
		case 'T':
		   global.mode = TRIANGLE;
		   glutIdleFunc(triangle); 
		   global.freeze = FALSE;
		   break;

		case 's':
		case 'S':
		   global.mode = RECTANGLE;
		   glutIdleFunc(rectangle); 
		   global.freeze = FALSE;
		   break;

		case 'f':
		case 'F':
		   global.freeze = !global.freeze; 
		   if (global.freeze == FALSE) { // toggle freeze effect 
		      (global.mode == TRIANGLE) 
			? glutIdleFunc(triangle) : glutIdleFunc(rectangle);
		   }
		   else {
			glutIdleFunc(NULL);
		   }	
		   break;

		case 'r':
		case 'R':
		   clearwin(); 
		   break;

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

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

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

	glutDisplayFunc(clearwin);
	glutIdleFunc(triangle);
	glutKeyboardFunc(keybd);

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

	glutMainLoop();
	return 0;
}