// #pragma comment (lib,"glut32.lib")
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include <GL/glut.h>

// window size (side)
int w_side = 600;

// position of camera
float x = 0, z = 5;
// look-at perspective to camera position
float look_x = 0, look_z = -1;

// angle for rotation
float angle = 0.0f;

// ground's size (side)
float g_side = 30;

void drawHouse () {
    glColor3f(0.0f, 1.0f, 0.0f); // Green

    glBegin(GL_QUADS);
      // Top face (y = 1.0f)
    glVertex3f( 1.0f, 1.0f, -1.0f);
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(-1.0f, 1.0f,  1.0f);
    glVertex3f( 1.0f, 1.0f,  1.0f);

    // Bottom face (y = -1.0f)
    glVertex3f( 1.0f, -1.0f,  1.0f);
    glVertex3f(-1.0f, -1.0f,  1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f( 1.0f, -1.0f, -1.0f);

    // Front face  (z = 1.0f)
    glVertex3f( 1.0f,  1.0f, 1.0f);
    glVertex3f(-1.0f,  1.0f, 1.0f);
    glVertex3f(-1.0f, -1.0f, 1.0f);
    glVertex3f( 1.0f, -1.0f, 1.0f);

    // Back face (z = -1.0f)
    glVertex3f( 1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f,  1.0f, -1.0f);
    glVertex3f( 1.0f,  1.0f, -1.0f);

    // Left face (x = -1.0f)
    glVertex3f(-1.0f,  1.0f,  1.0f);
    glVertex3f(-1.0f,  1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f,  1.0f);

    // Right face (x = 1.0f)
    glVertex3f(1.0f,  1.0f, -1.0f);
    glVertex3f(1.0f,  1.0f,  1.0f);
    glVertex3f(1.0f, -1.0f,  1.0f);
    glVertex3f(1.0f, -1.0f, -1.0f);
    glEnd();  // End of drawing color-cube
}

void drawGround () {
    glColor3f (0.9f, 0.9f, 0.9f);

    glBegin (GL_QUADS);
    glVertex3f (-g_side - 10, 0.0f, -g_side);
    glVertex3f (-g_side - 10, 0.0f,  g_side);
    glVertex3f ( g_side - 10, 0.0f,  g_side);
    glVertex3f ( g_side - 10, 0.0f, -g_side);
    glEnd ();
}

void changeSize (int w, int h) {
    h = (h > 0 ? h : 1);
    float ratio = (w * 1.0) / h;

    // Use the Projection Matrix
    glMatrixMode (GL_PROJECTION);

    // Reset Matrix
    glLoadIdentity ();

    // Set the viewport to be the entire window
    glViewport (0, 0, w, h);

    // Set the correct perspective.
    gluPerspective (45.0, ratio, 0.1, 100.0);

    // Get Back to the Modelview
    glMatrixMode (GL_MODELVIEW);
}

void render () {
    // Clear Color and Depth Buffers
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // Reset transformations
    glLoadIdentity ();

    // Set the camera
    gluLookAt (x,          1.0, z, // camera position
               x + look_x, 1.0, z + look_z, // look at
               0.0,        1.0, 0.0); // up

    drawGround ();
    for (int i = -3; i < 3; ++i) {
        for (int j = -3; j < 3; ++j) {
            glPushMatrix (); {
                glTranslatef (i * 10.0, 0, j * 10.0);
                drawHouse ();
            } glPopMatrix ();
        }
    }

    glutSwapBuffers ();
}

void changeMode (unsigned char key, int _x, int _y) {
}

void keyEvent (int key, int _x, int _y) {
    float fraction = 0.1f;

    switch (key) {
        case GLUT_KEY_LEFT :
            angle -= .01;
            look_x =  sin (angle);
            look_z = -cos (angle);
            break;
        case GLUT_KEY_RIGHT :
            angle += .01;
            look_x =  sin (angle);
            look_z = -cos (angle);
            break;
        case GLUT_KEY_UP :
            x += look_x * fraction;
            z += look_z * fraction;
            break;
        case GLUT_KEY_DOWN :
            x -= look_x * fraction;
            z -= look_z * fraction;
            break;
    }
}

int main (int argc, char **argv) {
    glutInit (&argc, argv);
    glutInitDisplayMode (GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowPosition (100, 100);
    glutInitWindowSize (2 * w_side, w_side);
    glutCreateWindow ("Graphics Lab Project");

    // register callbacks
    glutDisplayFunc (render);
    glutReshapeFunc(changeSize);
    glutIdleFunc (render);
    glutKeyboardFunc (changeMode);
    glutSpecialFunc (keyEvent);

    glEnable (GL_DEPTH_TEST);
    glutMainLoop ();

    return 0;
}