#include <GL/gl.h>
#include <GL/glu.h>
#include "aux.h"


void draw_triangle(void)
{
    glBegin(GL_LINE_LOOP);
    glVertex2f(0.0, 25.0); glVertex2f(25.0, -25.0); glVertex2f(-25.0, -25.0);
    glEnd();
}

void display_co_1(void) {
    glLoadIdentity (); glColor3f (1.0, 1.0, 1.0); draw_triangle (); }

void display_co_2(void) {
    glEnable (GL_LINE_STIPPLE);
    glLineStipple (1, 0xF0F0);
    glLoadIdentity ();
    glTranslatef (-20.0, 0.0, 0.0);
    draw_triangle ();
    glDisable (GL_LINE_STIPPLE);
}

void display_co_3(void)
{
    glEnable (GL_LINE_STIPPLE);
    glLineStipple (1, 0xF00F);
    glLoadIdentity ();
    glScalef (1.5, 0.5, 1.0);
    draw_triangle ();
    glDisable (GL_LINE_STIPPLE);
}

void display_co_4(void)
{
    glEnable (GL_LINE_STIPPLE);
    glLineStipple (1, 0x8888);
    glLoadIdentity ();
    glRotatef (90.0, 0.0, 0.0, 1.0);
    draw_triangle ();
    glDisable (GL_LINE_STIPPLE);
}

void myReshape();
int winWidth=500,winHeight=500;
void display(void) { myReshape(winWidth, winHeight); }

void myinit (void) { glShadeModel (GL_FLAT); }

void myReshape(int w, int h)
{
	winWidth=w; winHeight=h;
    glClearColor (0.0, 0.0, 0.0, 1.0);
    glClear (GL_COLOR_BUFFER_BIT);

    glMatrixMode(GL_PROJECTION); /* nur einmal */
    glLoadIdentity();
    if (w <= h)
        glOrtho (-50.0, 50.0, -50.0*(GLfloat)h/(GLfloat)w,
            50.0*(GLfloat)h/(GLfloat)w, -1.0, 1.0);
    else
        glOrtho (-50.0*(GLfloat)w/(GLfloat)h,
            50.0*(GLfloat)w/(GLfloat)h, -50.0, 50.0, -1.0, 1.0);
    glMatrixMode(GL_MODELVIEW); 

    glViewport(0, 0, w/2, h/2); display_co_1(); 
    glViewport(w/2, h/2, w, h); display_co_2();
    glViewport(0, h/2, w/2, h); display_co_3();
    glViewport(w/2, 0, w, h/2); display_co_4(); glFinish();

}


int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB);
    auxInitPosition (0, 0, winWidth, winHeight);
    auxInitWindow (argv[0]);
    myinit ();
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
}