Bird.java

package com.thomshutt.fappybird.drawable;

import com.badlogic.gdx.files.FileHandle;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.Animation;
import com.badlogic.gdx.graphics.g2d.Sprite;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.g2d.TextureRegion;
import com.badlogic.gdx.math.Circle;
import com.thomshutt.fappybird.Drawable;

import static java.lang.Math.max;
import static java.lang.Math.min;

public class Bird implements Drawable {

    public static final float TOUCH_ACCELERATION = 19f;
    private static final int GRAVITY = 55;
    private float velocityY = 0;

    private float y = 0;
    private float animationTime = 0f;
    private Animation animation;
    private TextureRegion textureBird;
    private Sprite spriteBird;
    private float x;
    private float birdHeight;
    private float birdWidth;
    private float maxBirdY;

    public Bird(Animation animation) {
        this.animation = animation;
        textureBird = animation.getKeyFrame(0);
        spriteBird = new Sprite(new TextureRegion(textureBird, 0, 0, 128, 128));
    }

    @Override
    public void tick(final float deltaTime){
        velocityY += GRAVITY * deltaTime;
        y = min(this.maxBirdY, y -= (0.4f * velocityY));
        animationTime += deltaTime;
        this.textureBird = animation.getKeyFrame(animationTime);
    }

    @Override
    public void screenTouched(boolean touched){
        if(touched){
            velocityY = -TOUCH_ACCELERATION;
        }
    }

    @Override
    public void draw(SpriteBatch batch) {
        spriteBird = new Sprite(new TextureRegion(textureBird, 0, 0, 128, 128));
        spriteBird.setSize(birdWidth, birdHeight);
        spriteBird.setOrigin(spriteBird.getWidth() / 2, spriteBird.getHeight() / 2);
        spriteBird.setPosition(this.x, this.y);
        spriteBird.setRotation(getTiltDegrees());
        spriteBird.draw(batch);
    }

    @Override
    public void resize(int width, int height) {
        this.birdWidth = height / 10f;
        this.birdHeight = height / 10f;
        this.x = -(width / 4);
        this.maxBirdY = (height / 2);
    }

    @Override
    public boolean isInCollisionWith(Bird bird) {
        return false;
    }

    private float getTiltDegrees() {
        if(this.velocityY <= 0) return min(30, -(this.velocityY * 3f));
        if(this.velocityY > 0) return max(-85, -(this.velocityY * 3f));
        return 0;
    }

    public Circle getCircle(){
        return new Circle(this.x + (this.birdWidth / 2), this.y + (this.birdHeight / 2), this.birdHeight / 2.5f);
    }

    public float getX() { return this.x; }
    public float getY() { return this.y; }

}