//square
//  Demonstration of Rotation Transformation
//  Blue square is fixed at the back and colorful square rotates.
//  The effect of z-buffer i.e. the intersection of two squares is demonstrated.
// T. Kosaka CS TNCT 16Aug2002

#include <stdio.h>
#include <math.h>
#include <GL/glut.h>
#include "GLDrawingtool3D.h"
#ifndef M_PI
#define M_PI 3.141592653589793
#endif

void userdraw(void);

void display(void)
{
    glClear( GL_COLOR_BUFFER_BIT);
    glClear(GL_DEPTH_BUFFER_BIT); // depth check
    userdraw();
    glutSwapBuffers();
}

void userdraw(void)
{
    static int tick=0;
    myInitView(0);

    point3D_t square0[]={
        {200,110,-100},{-200,110,-100},{-200,-110,-100},{200,-110,-100}
    };
    color_t colBlue={0,0,1};
    point3D_t square1[]={
        {100,100,180},{-100,100,180},{-100,-100,180},{100,-100,180}
    };
    color_t colors[]={{1,0,0},{0,1,0},{1,1,0},{1,0,1}};

    fillPolygon(square0,4,colBlue);

    glRotatef(tick,0,1,0); // angle[deg],x,y,z
    gradatePolygon(square1,colors,4);
    // Each point is automatically multiplied with the transformation matrix defined above

    tick++;
}

int main(int argc, char **argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode ( GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); // depth check
    glutInitWindowPosition(100,100);
    glutInitWindowSize(640,480);
    glutCreateWindow ("square");
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glViewport(0,0,640,480);               
    glutIdleFunc(display); // idle event call back
    glutDisplayFunc(display);
    glEnable(GL_DEPTH_TEST); // depth check (OpenGL inner Z-Buffer)
    glutMainLoop();
    return 0;
}