// Transform.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <math.h>
#include <GL/glut.h>

#ifndef M_PI
#define M_PI 3.141592
#endif

int width = 600;
int height = 600;

float worldAngle = 0;
float radiusWorld = 10;
float radiusMoon = 5;
float moonAngle = 0;

/**
 * Draws a circle on X-Z with radius and a specific
 * number of Line Segments (countLineSegments)
 */
void drawCircle(float radius, int countLineSegments){
    glBegin(GL_LINES);
    glColor3f(0,0,0);
    const float angleStep = (2*M_PI)/countLineSegments;
    float angle = 0.0;
    float startX = 0.0;
    float startY = radius;
    for(int step = 0; step<=countLineSegments;step++){
        glVertex3f(startX,0.0f,startY);
        startX = sinf(angle)*radius;
        startY = cos(angle)*radius;
        glVertex3f(startX,0.0f,startY);

        angle += angleStep;
    }
    glEnd();
}


/**
 * Draws a qubic Moon
 * with its global orbit radius(radiusMoon) and angle(moonAngle).
 */
void drawMoon(){
    glPushMatrix();
        glRotatef(moonAngle,0,1,0);
        glTranslatef(radiusMoon,0,0);

        glutSolidCube(1);

    glPopMatrix();
}

void display(void)
{
    // Farb- und Tiefenbuffer leeren
    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // Teekanne rendern.
    glColor3f(1,1,0);
    glutSolidTeapot(1);

    //Kreis malen
    drawCircle(10, 80);

    //World
    glPushMatrix();

        //glTranslatef(sin(worldAngle)*radiusWorld,0,cos(worldAngle)*radiusWorld);
        glRotatef(worldAngle,0,1,0);
        glTranslatef(radiusWorld,0,0);
        glutSolidSphere(1,30,30);

        //Moon Circle X-Z
        drawCircle(5,42);
        glColor3f(0,0,255);
        drawMoon();


        //Moon Circle X-Y
        glPushMatrix();
            glRotatef(90,0,0,1);
            drawCircle(5,42);
            glColor3f(255,0,0);
            drawMoon();
        glPopMatrix();

        //Moon Circle Y-Z
        glPushMatrix();
            glRotatef(90,1,0,0);
            drawCircle(5,42);
            glColor3f(0,255,0);
            drawMoon();
        glPopMatrix();

    glPopMatrix();

    glutSwapBuffers();
}

void timer(int val)
{
    glutTimerFunc(val,timer,val);
    glutPostRedisplay();

    //Move Moon and World (Moon at double speed)
    worldAngle += M_PI/10;
    moonAngle += M_PI/5;
}

void init()
{
    glEnable(GL_DEPTH_TEST);

    glViewport(0,0,width,height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-15.0, 15.0, -15.0, 15.0, 0.0, 200);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();
    gluLookAt(25.0, 11.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
}

int _tmain(int argc, _TCHAR* argv[])
{
    glutInit(&argc, (char**)argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(width, height);
    glutCreateWindow("Transformationen");

    glutDisplayFunc(display);
    glutTimerFunc(10,timer,10);

    init();
    glutMainLoop();
    return 0;
}