//////////////////////////////////////////////////////////////////
// Robert C. Duvall
// Fall 2001
//
#include <GL/glut.h>        // also includes glu and gl correctly
#include <stdlib.h>         // for exit
#include <stdio.h>          // for printf


//////////////////////////////////////////////////////////////////
// Globals

//
// Constants
//
const int WINDOW_WIDTH = 800;    // size of glut window
const int WINDOW_HEIGHT = 600;



//////////////////////////////////////////////////////////////////
//  Utility functions
//
void printVector (char * title, GLint vec[4])
{
    printf("%s\n", title);
    printf("  |");
    for (int k = 0; k < 4; k++)
    {
        printf(" %6d", vec[k]);
    }
    printf(" |\n");
    printf("\n");
}

void printMatrix (char * title, GLdouble mat[16])
{
    printf("%s\n", title);
    for (int r = 0; r < 4; r++)
    {
        printf("  |");
        for (int c = 0; c < 4; c++)
        {
   	    printf(" %6.2f", mat[r + c * 4]);
	}
        printf(" |\n");
    }
    printf("\n");
}


//////////////////////////////////////////////////////////////////
// User Functions
// These are the functions you will mostly be changing.
//
void initModel ()
{
}


void drawModel ()
{
    GLdouble mat[16];

    glPushMatrix();
      glColor3f(1.0, 1.0, 1.0);
      glTranslatef(0.0, 0.0, -1.0);
        glGetDoublev(GL_MODELVIEW_MATRIX, mat);  printMatrix("After translate:",  mat);
      glRotatef(60, 0.0, 1.0, 0.0);
        glGetDoublev(GL_MODELVIEW_MATRIX, mat);  printMatrix("After rotate:",  mat);
      glScalef(2.0, 2.0, 2.0);
        glGetDoublev(GL_MODELVIEW_MATRIX, mat);  printMatrix("After scale:", mat);
      glutWireCube(1.0);
    glPopMatrix();
}


//////////////////////////////////////////////////////////////////
// Callback Functions
// These functions are registered with the glut window and called 
// when certain events occur.
//
void onInit ()
// pre:  glut window has been initialized
// post: model has been initialized
{
    initModel();
    glClearColor(0.0, 0.0, 0.0, 0.0); 
    glEnable(GL_DEPTH_TEST); 
}


void onRedraw ()
// pre:  glut window needs to be refreshed
// post: model is drawn
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    drawModel();
    glutSwapBuffers();
}


void onResize (int width, int height)
// pre:  glut window has been resized
// post: resets cameras location and aspect to match window
{
    GLint vec[4];
    GLdouble mat[16];

    glViewport(0, 0, GLint(width), GLint(height));
      glGetIntegerv(GL_VIEWPORT, vec);  printVector("After veiwport:", vec);
      
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(60.0, GLfloat(width) / GLfloat(height), 0.5, 10.0);
      glGetDoublev(GL_PROJECTION_MATRIX, mat);  printMatrix("After perspective:", mat);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(0.0, 2.0, 4.0, 
	      0.0, 0.0, 0.0, 
	      0.0, 1.0, 0.0);
      glGetDoublev(GL_MODELVIEW_MATRIX, mat);  printMatrix("After lookat:", mat);
}


void onKeyPressed (unsigned char key, int /* mouseX */, int /* mouseY */)
// pre:  key has been pressed while mouse is within glut window
// post: animation may be paused or started, program may be exited
{
    switch (key)
    {
      case 'q': 
      case 27: // ESCAPE key
        exit(1);
        break;
    }
}


//////////////////////////////////////////////////////////////////
// Main Function
//
int main (int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitWindowSize(WINDOW_WIDTH, WINDOW_HEIGHT);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH | GLUT_RGBA);
    glutCreateWindow(argv[0]);

    onInit();
    glutDisplayFunc(onRedraw);
    glutReshapeFunc(onResize);
    glutKeyboardFunc(onKeyPressed);

    glutMainLoop();
    return 0;              // program should never get here
}