/*
 *  scene.c
 *  
 *  This program demonstrates the use of the GL lighting model.
 *  Objects are drawn using a grey material characteristic. 
 *  A single light source illuminates the objects.  The program
 *  is used to demonstrate the difference between single and
 *  double buffering.
 *
*/

/* Z increases eyeZ, z decreases eyeZ
 * Y increases eyeY, y decreases eyeY
 * If the z coordinate becomes negative, the "near" and "far" are
 * changed to negative
*/


#include <stdlib.h>
#include <GL/glut.h>

/*  Initialize material property and light source.  */

float spin = 0.0;
double near = 0.1;
double far = 120.0;
double fovy = 40.0;
double eyeX = 0.0;
double eyeY= 0.0;
double eyeZ = 5.0;

void myinit(void)
{
    // Light Properties
    GLfloat light_ambient[] = {0.0, 0.0, 0.0, 1.0};
    GLfloat light_diffuse[] = {1.0, 1.0, 1.0, 1.0};
    GLfloat light_specular[] = {1.0, 1.0, 1.0, 1.0};
    GLfloat light_position[] = {1.0, 1.0, 1.0, 0.0};
    GLfloat mat_specular[] = {0.5, 0.5, 0.5, 1.0};     
    GLfloat mat_shininess[]= {30.0};      

    glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
    glLightfv(GL_LIGHT0, GL_POSITION, light_position);

    // Material Properties
    glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);  
    glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess); 

    // Enable Various Components
    glEnable(GL_COLOR_MATERIAL);  
    glEnable(GL_LIGHT0);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHTING);

    glColorMaterial(GL_FRONT,GL_DIFFUSE); 
}

void spinDisplay()
{
    spin += 2.0;
    if (spin > 360.0)
        spin -= 360.0;
    glutPostRedisplay();
}

/* Draw various things using predefined GLUT objects */
void display(void)
{
    glLoadIdentity();
    gluPerspective( fovy, 1.0 , near, far);
    glMatrixMode(GL_MODELVIEW);

 //   spin += 5.0;
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    gluLookAt(eyeX, eyeY, eyeZ, 0.0, 0.0, 0.0,  0.0, 1.0, 0.);
    printf("X=%f, Y=%f, Z=%f near=%f far=%f\n", 
             eyeX, eyeY, eyeZ, near, far);

    glPushMatrix();

      glRotatef(20.0, 1.0,0.0, 0.0);
      glRotatef(spin, 0.0, 1.0, 0.0);

      glPushMatrix();  // Green Torus
        glTranslatef(-0.6, 0.0, 0.0);
        glRotatef(90.0, 1.0, 0.0, 0.0);
        glColor3f(0.0, 0.5, 0.0);
        glutSolidTorus(0.275, 0.85, 10, 15);
      glPopMatrix();

      glPushMatrix();  // Tall Yellow Box
        glTranslatef( 0.0, -0.5, -1.5);
        glRotatef(45.0, 0.0, 1.0, 0.0); 
        glScalef(1.0, 6.0, 1.0);    
        glColor3f(1.0, 1.0, 0.0);
        glutSolidCube(0.5);
      glPopMatrix();

      glPushMatrix();  // Flat Blue Box
        glTranslatef( 0.0, -2.0, -1.5);
        glRotatef(45.0, 0.0, 1.0, 0.0); 
        glScalef(1.0, 0.2, 1.0);    
        glColor3f(0.4, 0.5, 1.0);
        glutSolidCube(2.0);
      glPopMatrix();

      glPushMatrix();  // Red Ball
        glTranslatef(0.75, 0.0, -1.0);
        glColor3f(1.0, 0.0, 0.0);
        glutSolidSphere(0.8, 20, 10);
      glPopMatrix();

    glPopMatrix();
    glFlush();
    glutSwapBuffers();
 //   glutPostRedisplay();
}

void myReshape(int w, int h) 
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    
    gluPerspective( fovy, (GLfloat) h / (GLfloat) w , near, far );
    glMatrixMode(GL_MODELVIEW);

}

void mouse(int button, int state, int x, int y)
{
    switch (button)
    {
    case GLUT_LEFT_BUTTON:
        if (state == GLUT_DOWN)
            glutIdleFunc(spinDisplay);
        break;
    case GLUT_RIGHT_BUTTON:
        if (state == GLUT_DOWN)
            glutIdleFunc(NULL);
        break;
    default:
        break;
    }
}

void keyboard(unsigned char key, int x, int y)
{
    switch (key) {
    case 'F':
        if (fovy < 85.0)
           fovy += 5.0;
        break;
    case 'f':
        if (fovy > 5.0)
           fovy -= 5.0;
        break;
    case 'N':
        if (near < (far-10.0))
            near += 5.0;
        break;
    case 'n':
        if (near >= 10.1)
           near -= 5.0;
        break;
    case 'Z':
        eyeZ += 1.0;
        if (eyeZ > 0.0 && near < 0  && far < 0)
        {
            near *= -1.0;
            far *= -1.0;
        }
        break;
    case 'z':
        eyeZ -= 1.0;
        if (eyeZ < 0.0 && near > 0 && far >0)
        {
            near *= -1.0;
            far *= -1.0;
        }
        break;
    case 'Y':
        eyeY += 1.0;
        break;
    case 'y':
        eyeY-= 1.0;
        break;
    }
    glutPostRedisplay();
}


int main(int argc, char **argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH );
    glutInitWindowPosition(50, 50);
    glutInitWindowSize(500, 500);
    glutCreateWindow("3D Scene");
    myinit();
    glutKeyboardFunc(keyboard);
    glutMouseFunc(mouse);
    glutReshapeFunc(myReshape);
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;             /* ANSI C requires main to return int. */
}