//  rolling pentagon
//  PhongModel color calculation
// T. Kosaka CS TNCT 8Aug2002

#include <stdio.h>
#include <math.h>
#include <GL/glut.h>
#include "drawtools3D.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)
{
    drawLine(x,y,x+10,y+12);drawLine(x,y+12,x+10,y);
}

void drawcharY(float x,float y)
{
    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 drawcharZ(float x,float y)
{
    drawLine(x,y+12,x+10,y+12);drawLine(x+10,y+12,x,y);drawLine(x,y,x+10,y);
}

void drawAxes(matrix3D_t view)
{
#define HALFAXIS  220
#define HALFAXIS1 (HALFAXIS-10)
    point3D_t axes[14]={
        {-HALFAXIS,0,0},{HALFAXIS,0,0},{HALFAXIS1,5,0},{HALFAXIS1,0,0},{0,0,0},
        {0,-HALFAXIS,0},{0,HALFAXIS,0},{0,HALFAXIS1,5},{0,HALFAXIS1,0},{0,0,0},
        {0,0,-HALFAXIS},{0,0,HALFAXIS},{5,0,HALFAXIS1},{0,0,HALFAXIS1}
    };
    vector3D_t vec[14];
    int i;
    for (i=0;i<14;i++) {
        vec[i]=Point2Vector(axes[i]);
        vec[i]=view*vec[i];
    }
    drawPolyline(vec,14);
    drawcharX(vec[1].v[0],vec[1].v[1]);
    drawcharY(vec[6].v[0],vec[6].v[1]);
    drawcharZ(vec[11].v[0]-14,vec[11].v[1]);
}

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

void userdraw(void)
{
    static int tick=0;
    float theta=0.3*sin(0.05*tick)-0.5;
    matrix3D_t tilting=rotationXMTX(0.5)*rotationYMTX(theta);
    matrix3D_t conv=scalingMTX(-1,-1,-1);
    vector3D_t unitz={0,0,1,1};
    vector3D_t LightVector0=rotationYMTX(0.2)*rotationXMTX(-1.2)*unitz;
    vector3D_t LightVector=tilting*LightVector0;
    vector3D_t ViewVector={0,0,1,1};
    color_t white={1.,1.,1.};
    color_t cyan={0.,1.,1.};
    color_t blue={0.,0.,1.};
    point3D_t pentagon[5];
    vector3D_t vec[10];
    vector3D_t normalVector;
    matrix3D_t rot1,trans,mat;
    color_t color;
    int i;

    setColor(white);
    drawAxes(tilting);

    for (i=0;i<5;i++) {
        float theta=M_PI*(2.*i/5+0.5);
        pentagon[i].x=80.*cos(theta);
        pentagon[i].y=80.*sin(theta);
        pentagon[i].z=0.;
    }

    setColor(cyan);
    rot1=rotationXMTX(0.05*tick);
    trans=translationMTX(0,66,0);
    mat=tilting*rot1*trans;
    for (i=0;i<5;i++) {
        vec[i]=Point2Vector(pentagon[i]);
        vec[i]=mat*vec[i];
    }
    normalVector=(vec[1]-vec[0])^(vec[2]-vec[0]);
    normalVector=unitVector(normalVector);
    if (0.<normalVector.v[2]) {
        color=PhongModel(LightVector,normalVector,ViewVector,cyan);
    } else {
        normalVector=conv*normalVector;
        color=PhongModel(LightVector,normalVector,ViewVector,blue);
    }
    fillPolygon(vec,5,color);

    tick++;
}

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