I was just wondering how to make a actor jump. I have seen it done in levels but i never could figure it out.
CrazyGamer1122 wrote ...
2012/7/30
How to make Jump level?
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make an instance variable:
in act, put this code:
this will move the Actor down forever.
Let's say you want to jump when the method mustJump returns true (you can replace that of course), put this in act:
Does this work? If you need further assistance, just ask.
private int gravity = 0;
setLocation(getX(), getY() -gravity); gravity--;
if (mustJump() ) {
gravity = 20;
}
You also want to make the player stop falling when he hits the ground.
A full implementation might look something like this:
I hope this helps.
public void act()
{
//fill this in with what you want,
//but add this here:
if(mustJump())
jump();
checkFall();
}
private void checkFall()
{
if(!onGround())
fall();
}
private boolean onGround()
{
int myHeight = getImage().getHeight();
Actor ground = getOneObjectAtOffset(0, myHeight/2, Ground.class);
if(ground != null)//if the ground is really there...
return true;
//(if not, return false)
return false;
}
//this is quite like SPower's method
private void fall()
{
setLocation(getX(), getY() + gravity);
gravity++;//the player will accelerate as he falls
}
private void jump()
{
if(onGround())
gravity -= 20;//or choose 10 or 15 or whatever works
}
Thanks to both of you for the help. i will post back if i need anymore help on the topic.
I just tried out the code for mustJump().... and it says incompatible types on this part right here
does it have something to do with the parenthesis?
if ( mustJump() )
I believe that was a bit of pseudo-code by SPower's part. You have to put in there the conditions required to trigger the jump (such as: if (onGround && Greenfoot.isKeyDown("up")) ).
i just tried to recompile and i realized there is no method for mustJump() i am kind of new to greenfoot and i do not know what i should put in the method. i would really appreciate it.
@CrazyGamer1122, replace mustJump() with the code danpost provided:
onGround && Greenfoot.isKeyDown("up")so it would look like this?
sorry if i am being bothersome, i just have not been on greenfoot in a while and i have forgotten most of the API and methods.
public void act()
{
//fill this in with what you want,
//but add this here:
if(onGround && (Greenfoot.isKeyDown("up")))
jump();
checkFall();
}
private void checkFall()
{
if(!onGround())
fall();
}
private boolean onGround()
{
int myHeight = getImage().getHeight();
Actor ground = getOneObjectAtOffset(0, myHeight/2, Ground.class);
if(ground != null)//if the ground is really there...
return true;
//(if not, return false)
return false;
}
//this is quite like SPower's method
private void fall()
{
setLocation(getX(), getY() + gravity);
gravity++;//the player will accelerate as he falls
}
private void jump()
{
if(onGround())
gravity -= 20;//or choose 10 or 15 or whatever works
}
}
thanks that took care of a major problem but i compiled and it gave me a error "could not find symbol- variable onGround" would i have to give it a new method or is there some other way to fix this? if i do need a new method please include what to type in the method. thanks for responding so quickly by the way.
okay it compiles successfully now but i was wondering if there was any thing i needed to put in the code to interact with the actor Ground?
i tried with this as my person's code -- and when i pressed the key, nothing happened to the person. am i missing something?
import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
/**
* Write a description of class actor here.
*
* @author (your name)
* @version (a version number or a date)
*/
public class actor extends Actor
{
/**
* Act - do whatever the actor wants to do. This method is called whenever
* the 'Act' or 'Run' button gets pressed in the environment.
*/
/**
* An example of a method - replace this comment with your own
*
* @param y a sample parameter for a method
* @return the sum of x and y
*/
private int gravity = 0;
public void act()
{
//fill this in with what you want,
//but add this here:
if(onGround() && (Greenfoot.isKeyDown("up")))
jump();
checkFall();
}
private void checkFall()
{
if(!onGround())
fall();
}
private boolean onGround()
{
int myHeight = getImage().getHeight();
Actor ground = getOneObjectAtOffset(0, myHeight/2, Ground.class);
if(ground != null)//if the ground is really there...
return true;
//(if not, return false)
return false;
}
//this is quite like SPower's method
private void fall()
{
setLocation(getX(), getY() + gravity);
gravity++;//the player will accelerate as he falls
}
private void jump()
{
gravity -= 20;//or choose 10 or 15 or whatever works
}
}
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