Sign in to follow this  

Jumping a sprite in a Box2D Platformer

Recommended Posts

So I am just working on a demo for a game that I still be starting soon. I just found out about Box2D today and I was wondering if anyone knows how I would jump a sprite.


Currently, I can press the up key and I can infinitely soar into the sky. I have gravity working fine. I have seen people use a "jump timer". I understand the concept, but do not understand how to code this up. Also, I have failed at all attempts to check in my "man" is touching the ground. What is the best way to do this?


Here is my update code:

		function update() {		    man.body.setZeroVelocity();		    man.body.fixedRotation = true;		    if (cursors.left.isDown)		    {		    	man.scale.x = -.2;		        man.body.moveLeft(400);'run', 10, true);		    }		    else if (cursors.right.isDown)		    {		    	man.scale.x = .2;		        man.body.moveRight(400);'run', 10, true);		    }		    if (cursors.up.isDown)		    {		    	        		man.body.velocity.y = -750;		    }		    else if (cursors.down.isDown)		    {		        man.body.moveDown(400);		    }		    if (!cursors.left.isDown && !cursors.right.isDown) {		    	man.animations.stop();		    	man.frameName = "shooting1.png";		    };		}

And Here is what it looks like:

Share this post

Link to post
Share on other sites

maybe this will help?


I found that doing this:

phyPlayer.ApplyImpulse( {'x' : 0, 'y' : -2}, phyPlayer.GetWorldCenter() );

Works pretty well.  phyPlayer is the body returned by world.CreateBody(myBodyDef);


Now, could you tell me how you made your lines? :)

Share this post

Link to post
Share on other sites

This is my collision listener so far, you can play with it. It tells you what 2 bodies collided. In my code, it ignores any collision with a body that doesn't have a userData set. userData is set in the bodyDef, box2d doesn't care what it is: object, number, string, etc.  I'm currently assigning it a string ex "player" or "death" <- object that instantly kills player. I don't assign one to solid ground, because there's currently no need for me to do anything when my player touches solid ground 'cause box2d takes care of what I need.


var listener = new b2d.b2ContactListener;//console.log(world);    listener.BeginContact = function(contact) {	var a = contact.GetFixtureA().GetBody().GetUserData()    	var b = contact.GetFixtureB().GetBody().GetUserData();    	//if we have assigned userData to both bodies, it's important enough to check into    	if (a &&  {    		console.log("Collision between: " + a + " & " + ;    	}	             }    listener.EndContact = function(contact) {        //console.log(contact.GetFixtureA().GetBody().GetUserData());    }    listener.PostSolve = function(contact, impulse) {            }    listener.PreSolve = function(contact, oldManifold) {    }

Also, there's a b2Body.isAwake() function that will return false if the b2Body is "resting", but I haven't gotten into that yet.  Much like yourself, I have just started playing with box2d.


Sorry if this reply seems too vague for your answer, I'm currently on my lunch break :)


edit: If you want to see if the player touched anything at all, put this in listener.BeginContact.

if (a == 'player' || b == 'player') {    //do what ever you need there}

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.