// A rotating star(pentagram) with class
// T. Kosaka CS TNCT 2Aug2002

#include <stdio.h>
#include <math.h>
#include <GL/glut.h>
#include "CGCore2D.h"
#ifndef M_PI
#define M_PI 3.141592653589793
#endif

void userdraw(void);

void display(void)
{
    glClear( GL_COLOR_BUFFER_BIT);
    userdraw();
    glutSwapBuffers();
}

//////////////////////////////////////////////////////////////////
void drawcharX(float x,float y) //文字 x の表示
{
    C_Color white(1.,1.,1.);
    C_Line charX1(x,y,x+10,y+12,white); charX1.draw();
    C_Line charX2(x,y+12,x+10,y,white); charX2.draw();
}

void drawcharY(float x,float y) //文字 y の表示
{
    C_Color white(1.,1.,1.);
    C_Line charY1(x+5,y,x+5,y+7,white); charY1.draw();
    C_Line charY2(x,y+12,x+5,y+7,white); charY2.draw();
    C_Line charY3(x+10,y+12,x+5,y+7,white); charY3.draw();
}

void drawAxes(void) // xy軸の表示
{
    C_Color white(1.,1.,1.);
    C_Line charAX1(-310,0,310,0,white); charAX1.draw();
    C_Line charAX2(310,0,300,5,white); charAX2.draw();
    C_Line charAX3(310,0,300,-5,white); charAX3.draw();
    drawcharX(300,-20);
    C_Line charAY1(0,-230,0,230,white); charAY1.draw();
    C_Line charAY2(0,230,5,220,white); charAY2.draw();
    C_Line charAY3(0,230,-5,220,white); charAY3.draw();
    drawcharY(-20,220);
}

//////////////////////////////////////////////////////////////////

void userdraw(void)
{
    static int tick=0;
    C_Point pentagram00[5];
    int i;
    for (i=0;i<5;i++) {
        float theta=M_PI*(4.*i/5+0.5);
        pentagram00[i].x=20.*cos(theta);
        pentagram00[i].y=20.*sin(theta);
    }

    C_Color cyan(0.,1.,1.);
    C_Polygon pentagram0(pentagram00,5,cyan);
    C_Polygon pentagram;
    C_Matrix mat,trans,rot1,rot2;
    drawAxes();
    trans.setTranslation(160,0);
    rot1.setRotation(tick*0.1);
    rot2.setRotation(tick*0.03);
    mat=rot2*trans*rot1;
    pentagram=mat*pentagram0;
    pentagram.draw();
    tick++;
}

int main(int argc, char **argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode ( GLUT_DOUBLE | GLUT_RGB );
    glutInitWindowPosition(100,100);
    glutInitWindowSize(640,480);
    glutCreateWindow ("Rotating star");
    glClearColor(0.0, 0.0, 0.0, 0.0);
    gluOrtho2D(-320., 320., -240.0, 240.0);
      // Define the dimensions of the Orthographic Viewing Volume
    glutIdleFunc(display); // idle event call back
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}