/*
 * mondrian.c
 * 
 * Draw a bunch of colored rectangles in the style of the painter Mondrain.
 *
 *   Left button: randomizes the pattern
 *   Middle button: toggles between filled and outlined rectangles.
 *
 * Pat Hanrahan 1/97
 */

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

GLint Width = 512, Height = 512;
int   Times = 100;
int   FillFlag  = 1;
long  Seed = 0;

void
DrawRect( float x1, float y1, float x2, float y2, int FillFlag )
{
    glBegin(FillFlag ? GL_QUADS : GL_LINE_LOOP);
	glVertex2f(x1, y1);
	glVertex2f(x2, y1);
	glVertex2f(x2, y2);
	glVertex2f(x1, y2);
    glEnd();
}

void
Display(void)
{
    int i;
    float x1, y1, x2, y2;
    float r, g, b;

    srand48(Seed);

    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT);

    for( i = 0; i < Times; i++ ) {
	r = drand48();
	g = drand48();
	b = drand48();
	glColor3f( r, g, b );

	x1 = drand48() * Width;
	y1 = drand48() * Height;
	x2 = drand48() * Width;
	y2 = drand48() * Height;
        DrawRect( x1, y1, x2, y2, FillFlag );
    }

    glFinish();
}

void
Reshape(GLint w, GLint h)
{
    Width = w;
    Height = h;

    glViewport(0, 0, w, h);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0, w, 0, h, -1.0, 1.0);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void
Mouse(int button, int state, int x, int y)
{
    if( state == GLUT_DOWN ) {
	switch( button ) {
	    case GLUT_LEFT_BUTTON:
		Seed = mrand48();
		break;
            case GLUT_MIDDLE_BUTTON:
		FillFlag = !FillFlag;
		break;
	}
	glutPostRedisplay();
    }
}

void
Keyboard( unsigned char key, int x, int y )
{
#define ESCAPE '\033'

    if( key == ESCAPE )
        exit(0);
}

main(int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB);
    glutInitWindowSize(Width, Height);
    glutCreateWindow("Mondrian (RGB)");

    glutDisplayFunc(Display);
    glutReshapeFunc(Reshape);
    glutKeyboardFunc(Keyboard);
    glutMouseFunc(Mouse);

    glutMainLoop();
}