Solar System - Transformations

DrRakha

Solar System - Transformations example :

Code:

#include "windows.h"
#include <gl\glut.h>

#define sunRaduis 0.4
#define earthRaduis 0.06
#define moonRaduis 0.016

GLfloat rotationSpeed = 0.1;
GLfloat daysInYear = 365;   
GLfloat year = 0.0; //degrees
GLfloat day = 0.0;
GLfloat moonAroundEarth = 0.0;
GLfloat moonItsSelf = 0.0;
GLfloat earthOrbitRadius = 1.0;
GLfloat moonOrbitRadius = 0.1;
GLfloat moonAroundEarthRate = 2 * rotationSpeed;
GLfloat moonRotationItselfRate = 5.0 * rotationSpeed;
GLfloat dayRate = 5.0 * rotationSpeed;
GLfloat yearRate = daysInYear / 360.0 * dayRate * rotationSpeed;
void drawSolarSystem(void);
void Initialization(void);
void displayFunc(void);
void reshapeFunc(int x, int y);
void idleFunc(void);
int main(int argc, char* argv[])
{

    // Initialization for glut 
    glutInit(&argc, argv);
    // set the buffer mode ( double and colors (RGB)
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    // set the window frame size 
    glutInitWindowSize(700,700);
    glutCreateWindow("Solar system");
    Initialization();
    // reshape call back function reference setting.
    glutReshapeFunc(reshapeFunc);
    // display call back function reference setting
    glutDisplayFunc(displayFunc);
    //  idle callback function reference setting ( used in animation )
    glutIdleFunc(idleFunc);
    // enters the GLUT event processing loop
    glutMainLoop();
    return 0;
}
void drawSolarSystem(void)
{

    glPushMatrix();
    /*
    glPushMatrix()
        pushes the current matrix stack down by one, duplicating the current matrix. That is,
            after a glPushMatrix call, the matrix on top of the stack is identical to the one below it.
        
    */
    
    
        gluLookAt(    0.0,0.0,-4.0,
                    0.0,0.0,1.0,
                    0.0,-3.0,0.0);
        //gluLookAt
        //creates a viewing matrix derived from an eye point, a reference point indicating the
        //center of the scene, and an UP vector

        // Color of the sun. 
        glColor3f(1.0,0.8,0.3);
        // Drawing the sun. 
        glutSolidSphere(sunRaduis,50,50);
        glPushMatrix();
        
            glRotatef(year,0.0,1.0,0.0); //rotation for earth
            glTranslatef(earthOrbitRadius,0.0,0.0); // translation for earth.
            glRotatef(-year,0.0,1.0,0.0);
            glPushMatrix();
                glRotatef(day,0.25,1.0,0.0);
                glColor3f(0.4,0.6,0.3);
                //Drawing the earth
                glutSolidSphere(earthRaduis,10,10);   
                 
            glPopMatrix();
            // rotation for moon.
            glRotatef(moonAroundEarth,0.0,1.0,0.0);
            // translation for moon.
            glTranslatef(moonOrbitRadius,0.0,0.0);
         
            // around earth rotation.
            glRotatef(-moonAroundEarth,0.0,1.0,0.0);
            // moon rotation about it self.
            glRotatef(moonItsSelf,0.0,1.0,0.0);

            glColor3f(0.3,0.3,0.5);
            // draw the moon
            glutSolidSphere(moonRaduis,8,8);
        glPopMatrix();
                
    glPopMatrix();
}

void Initialization(void)
{
    // background color
    glClearColor(0.0,0.0,0.0,0.0);
    glClearDepth(10.0);


    // GL_MODELVIEW :Applies subsequent matrix operations to the modelview matrix stack.
    /*
The modelview matrix is for transformation of geometry from model to view space 
(therefore the camera/view transform most correctly goes in the modelview matrix).
    */
    glMatrixMode(GL_MODELVIEW);
    // replace the current matrix with the identity matrix
    glLoadIdentity();
}

void displayFunc(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    drawSolarSystem();
    // flush to screen.
    glFlush();
    // swap buffers , yes we need this ( double buffering used!)
    glutSwapBuffers();
}

void reshapeFunc(int x, int y)
{
    if (y == 0 || x==0) return;
 
    glLoadIdentity();
    gluPerspective(40.0,(GLdouble)x/(GLdouble)y,0.5,20.0);
    glMatrixMode(GL_MODELVIEW);
    glViewport(0,0,x,y);
    displayFunc();
}

void idleFunc(void)
{
    // idle event call back in animation , here we increase the values and redisply .
    day += dayRate;
    year += yearRate;
    moonItsSelf += moonRotationItselfRate;
    moonAroundEarth += moonAroundEarthRate;
    displayFunc();
}
 

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Solar System - Transformations