// a minimalist JavaScript standalone 3d game engine.

// a minimalist JavaScript standalone 3d game engine.

// Game specific functions

function Player(x,y,z){
    this.x = x;
    this.y = y;
    this.z = z;
    this.up = true;
}

Player.prototype.update = function(){
    // update the position of the player
    if (this.up){
        this.y += this.velocityY;
        if (this.y < 0) {
            this.up = false;
        }
    }
    else{
        this.y -= this.velocityY;
        if (this.y > 0) {
            this.up = true;
        }
    }

    // update the player's position
    this.x += this.velocityX;
    this.z += this.velocityZ;

    // check if the player collided with a wall
    if (this.x < 0) {
        this.x = 0;
        this.velocityX = -this.velocityX;
    }
    else if (this.x > window.innerWidth - 1) {
        this.x = window.innerWidth - 1;
        this.velocityX = -this.velocityX;
    }

    if (this.z < 0) {
        this.z = 0;
        this.velocityZ = -this.velocityZ;
    }
    else if (this.z > window.innerHeight - 1) {
        this.z = window.innerHeight - 1;
        this.velocityZ = -this.velocityZ;
    }

    // update the player's rotation
    this.rotation += this.rotationSpeed;
}

// draw the player
Player.prototype.draw = function(){
    // set the position of the player
    gl.glTranslated(this.x, this.y, this.z);

    // set the rotation of the player
    gl.glRotated(this.rotation, 0, 0, 1);

    // draw the player
    gl.glBegin(gl.GL_QUADS);
        gl.glColor3f(1.0, 0.0, 0.0);
        gl.glVertex3f(0.0, 0.0, 0.0);
        gl.glVertex3f(0.0, this.y, 0.0);
        gl.glVertex3f(0.0, this.y, this.z);
        gl.glVertex3f(0.0, 0.0, this.z);
        gl.glVertex3f(this.x, 0.0, this.z);
    gl.glEnd();
}

function Wall(x,y,z){
    this.x = x;
    this.y = y;
    this.z = z;
    this.velocityX = -0.2;
    this.velocityY = -0.2;
    this.velocityZ = 0.2;
    this.rotationSpeed = 1.0;
}

Wall.prototype.update = function(){
    // update the position of the wall
    if (this.x < 0) {
        this.x = 0;
        this.velocityX = -this.velocityX;
    }
    else if (this.x > window.innerWidth - 1) {
        this.x = window.innerWidth - 1;
        this.velocityX = -this.velocityX;
    }

    if (this.y < 0) {
        this.y = 0;
        this.velocityY = -this.velocityY;
    }
    else if (this.y > window.innerHeight - 1) {
        this.y = window.innerHeight - 1;
        this.velocityY = -this.velocityY;
    }

    if (this.z < 0) {
        this.z = 0;
        this.velocityZ = -this.velocityZ;
    }
    else if (this.z > window.innerHeight - 1) {
        this.z = window.innerHeight - 1;
        this.velocityZ = -this.velocityZ;
    }

    // update the wall's rotation
    this.rotation += this.rotationSpeed;
}

Wall.prototype.draw = function(){
    // set the position of the wall
    gl.glTranslated(this.x, this.y, this.z);

    // set the rotation of the wall
    gl.glRotated(this.rotation, 0, 0, 1);

    // draw the wall
    gl.glBegin(gl.GL_QUADS);
        gl.glColor3f(0.0, 0.0, 0.0);
        gl.glVertex3f(0.0, 0.0, 0.0);
        gl.glVertex3f(0.0, this.y, 0.0);
        gl.glVertex3f(0.0, this.y, this.z);
        gl.glVertex3f(0.0, 0.0, this.z);
    gl.glEnd();
}

// the main game loop
function main() {
    // initialize all variables
    window.requestAnimationFrame(main);

    // set the resolution of the window
    gl.glViewport(0, 0, window.innerWidth, window.innerHeight);

    // set the projection matrix
    gl.glMatrixMode(gl.GL_PROJECTION);
    gl.glLoadIdentity();
    gl.glOrtho(0.0, window.innerWidth, 0.0, window.innerHeight, 0.1, 100.0);

    // set the model view matrix
    gl.glMatrixMode(gl.GL_MODELVIEW);
    gl.glLoadIdentity();

    // set the player's position
    Player.prototype.x = window.innerWidth/2;
    Player.prototype.y = window.innerHeight/2;
    Player.prototype.z = 0.0;

    // set the wall's position
    Wall.prototype.x = window.innerWidth/2;
    Wall.prototype.y = window.innerHeight/2;
    Wall.prototype.z = window.innerHeight/2;

    // start the game loop
    loop();
}

// main game loop
function loop() {
    // set the game time
    requestAnimationFrame(loop);

    // update the player's position
    Player.prototype.update();

    // update the wall's position
    Wall.prototype.update();

    // clear the screen and set the color to black
    gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT);
    gl.glColor3f(0.0, 0.0, 0.0);