// morphing
//  pentagon-square-19gram
//  The shape changes itself.
// T. Kosaka CS TNCT 2001

#include <stdio.h>
#include <math.h>
#include <GL/glut.h>
#include "drawShape2D.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
{
    drawLine(x,y,x+10,y+12);drawLine(x,y+12,x+10,y);
}

void drawcharY(float x,float y) //文字 y の表示
{
    drawLine(x+5,y,x+5,y+7);drawLine(x,y+12,x+5,y+7);drawLine(x+10,y+12,x+5,y+7);
}

void drawAxes(void) // xy軸の表示
{
    drawLine(-310,0,310,0);drawLine(310,0,300,5);drawLine(310,0,300,-5);
    drawcharX(300,-20);
    drawLine(0,-230,0,230);drawLine(0,230,5,220);drawLine(0,230,-5,220);
    drawcharY(-20,220);
}
//////////////////////////////////////////////////////////////////
point2D_t interpolate(point2D_t a, point2D_t b, float r)
{
    // 0.0<=r<=1.0  AC:CB=r:(1-r)
    if (r<0.0) r=0.0;
    if (1.0<r) r=1.0;
    point2D_t c;
    float r1=1.0-r;
    c.x=r1*a.x+r*b.x;
    c.y=r1*a.y+r*b.y;
    return c;
}

void makeSquare(point2D_t p[],float r)
{
    int i,j;
    for (i=0;i<5;i++) {
        p[5*i].x=r*cos((0.5*i+0.25)*M_PI);
        p[5*i].y=r*sin((0.5*i+0.25)*M_PI);
    }
    for (i=0;i<4;i++) {
        for (j=1;j<5;j++) {
            p[5*i+j]=interpolate(p[5*i],p[5*i+5],0.2*j);
        }
    }
}

void makePentagram(point2D_t p[],float r)
{
    int i,j;
    for (i=0;i<6;i++) {
        p[4*i].x=r*cos((0.8*i+0.5)*M_PI);
        p[4*i].y=r*sin((0.8*i+0.5)*M_PI);
    }
    for (i=0;i<5;i++) {
        for (j=1;j<4;j++) {
            p[4*i+j]=interpolate(p[4*i],p[4*i+4],0.25*j);
        }
    }
}

void make20gram(point2D_t p[],float r)
{
    int i;
    for (i=0;i<20;i++) {
        p[i].x=r*cos(i*M_PI*18/19.);
        p[i].y=r*sin(i*M_PI*18/19.);
    }
}

void userdraw(void)
{
    static int tick=0;
    int disp=(tick/100)%6;
    float rtick=(tick%100)/80.;
    color_t white={1.,1.,1.};
    color_t cyan={0.,1.,1.};
    point2D_t square[40];
    point2D_t pentagram[40];
    point2D_t ngram20[40];
    point2D_t shape[40];
    int i;
    makeSquare(square,150);
    makePentagram(pentagram,150);
    make20gram(ngram20,150);
    setColor(white);
    drawAxes();
    setColor(cyan);
    switch(disp) {
    case 0:
        for(i=0;i<20;i++) {
            shape[i]=interpolate(square[i],pentagram[i],rtick);
        }
        drawPolygon(shape,20);
        break;
    case 1:
        for(i=0;i<20;i++) {
            shape[i]=interpolate(pentagram[i],ngram20[i],rtick);
        }
        drawPolygon(shape,20);
        break;
    case 2:
        for(i=0;i<20;i++) {
            shape[i]=interpolate(ngram20[i],square[i],rtick);
        }
        drawPolygon(shape,20);
        break;
    case 3:
        for(i=0;i<20;i++) {
            shape[i]=interpolate(square[i],ngram20[i],rtick);
        }
        drawPolygon(shape,20);
        break;
    case 4:
        for(i=0;i<20;i++) {
            shape[i]=interpolate(ngram20[i],pentagram[i],rtick);
        }
        drawPolygon(shape,20);
        break;
    case 5:
        for(i=0;i<20;i++) {
            shape[i]=interpolate(pentagram[i],square[i],rtick);
        }
        drawPolygon(shape,20);
        break;
    default:
        break;
    }
    tick++;
}

int main(int argc, char **argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode ( GLUT_DOUBLE | GLUT_RGB );
    glutInitWindowPosition(100,100);
    glutInitWindowSize(640,480);
    glutCreateWindow ("figures");
    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;
}