Platformer: Getting Started

Today we will build a basic platformer game. We will start with a player and a platform, and we will have the player "fall" until it hits the "ground" (or platform).

import greenfoot.*;  // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)

/**
 * Write a description of class Player here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Player extends Actor
{
    private int vSpeed = 0;
    private int acceleration = 1;

    /**
     * Act - do whatever the Player wants to do. This method is called whenever
     * the 'Act' or 'Run' button gets pressed in the environment.
     */
    public void act() 
    {
        checkFall();
    }   
    
    public void fall()
    {
        setLocation(getX(), getY() + vSpeed);
        if(vSpeed <=9)
        {
            vSpeed = vSpeed + acceleration;
        }  
    }

    public boolean onGround()
    {
        int spriteHeight = getImage().getHeight();
        int lookForGround = (int)(spriteHeight/2) + 5;
        Actor ground = getOneObjectAtOffset(0, lookForGround, Platform.class);
        if(ground == null)
        {
            return false;
        }
        else
        {
            moveToGround(ground);
            return true;
        }
    }

    public void moveToGround(Actor ground)
    {
        int groundHeight = ground.getImage().getHeight();
        int newY = ground.getY() - (groundHeight + getImage().getHeight())/2;
        setLocation(getX(), newY);
    }
    
    public void checkFall()
    {
        if(onGround())
        {
            vSpeed = 0;
        }
        else
        {
            fall();
        }
    }
}