Bouncy / Jitter Physics on world shapes after following platformer tutorial

[Nick Newman]

So I just got done following the platformer tutorial. This is pretty weird, watch: 

Basically, whenever I apply movement towards the sides of the shape my character bounces from them. This doesn't happen for top or bottom velocities though.

Player Entity:

game.Player = me.Entity.extend({

  init : function (x, y, data) {

//var image = me.loader.getImage("player");

//console.log(data);

  this.data = data;

  this.onBodyEntered = false;

       this._super(me.Entity, "init", [x, y, {

            image: "player",

            width: 72,

            height: 144

        }]);

this.velx = 450;

this.vely = 450;

// ensure the player is updated even when outside of the viewport

//this.alwaysUpdate = true;

//this.maxX = me.game.viewport.width - this.width;

//this.maxY = me.game.viewport.height - this.height;

this.chooseShipImage();

//this.renderable.alpha = 0.5;

this.body.setVelocity(0, 0);

//Collision Shape

this.body.shapes[0] = new me.Ellipse(this.width/2, this.height/2, this.width/1.3, this.height/1.3);

console.log(this.body)

//this.body.collisionType = me.collision.types.ALL_OBJECT;

  },

  chooseShipImage: function () {

        var frame = ~~(Math.random() * 3);

        this.renderable.addAnimation("walk", [0, 1, 2], 200);

        this.renderable.setCurrentAnimation("walk");

  },

  update : function (dt) {

this.body.update(dt);

if(!me.collision.check(this)){ // They are not colliding

this.onBodyEntered = false

}

//console.log(this.pos.z);

 

 

    //this.pos.x = this.pos.x.clamp(0, this.maxX);

    //this.pos.y = this.pos.y.clamp(0, this.maxY);

//return true;

    //return this.renderable.update(dt);

//return (this._super(me.Entity, 'update', [dt]) || this.body.vel.x !== 0 || this.body.vel.y !== 0);

return this._super(me.Entity, 'update', [dt]);

 

 

},

onBodyEnter: function(response, other){

if(response.b.name == "WarpEntity"){ // -- warp_to

var warp_to = WARPS[response.b.warp_to];

this.pos.x = warp_to.pos.x;

this.pos.y = warp_to.pos.y;

play("teleport", false, false, this);

}

},

onCollision : function (response, other) {

//Handle Map Entity Collision

if(this.onBodyEntered == false){

this.onBodyEnter(response, other);

this.onBodyEntered = true;

}

//Handle Collision types (maps mostly)

//console.log(response.b.body.collisionType)

//console.log(other.type)

 switch (response.b.body.collisionType) {

case me.collision.types.WORLD_SHAPE:

 // Simulate a platform object

 if (other.type === "platform") {

if (this.body.falling && !me.input.isKeyPressed('down') &&

 // Shortest overlap would move the player upward

 (response.overlapV.y > 0) &&

 // The velocity is reasonably fast enough to have penetrated to the overlap depth

 (~~this.body.vel.y >= ~~response.overlapV.y)) {

 // Disable collision on the x axis

 response.overlapV.x = 0;

 // Repond to the platform (it is solid)

 return true;

}

// Do not respond to the platform (pass through)

return false;

 }

 return true;

 break;

case me.collision.types.ENEMY_OBJECT:

 if ((response.overlapV.y>0) && !this.body.jumping) {

// bounce (force jump)

this.body.falling = false;

this.body.vel.y = -this.body.maxVel.y * me.timer.tick;

// set the jumping flag

this.body.jumping = true;

 }

 else {

// let's flicker in case we touched an enemy

this.renderable.flicker(750);

console.log("Flickering:" +response);

 }

 // Fall through

default:

 // Do not respond to other objects (e.g. coins)

 return false;

 }

 // Make the object solid

 //return true;

}

});

Haven't changed really anything else from the tutorial.. Thanks in advance!

[melonJS]

Huh? I cannot really see your code properly, but if you take the platformer example, it works properly when walking towards the crates.

Could this be a bug in the ellipse vs polygon collision handling/response ? i must admit i never use it, just using polygons all the time.

[Jay Oster]

Ellipse collision detection only works with perfect circles. The challenge with non-circular ellipses is that they can be rotated... So the current SAT shape tests just don't take multi-axis radii into account.

On Thu, Nov 17, 2016 at 5:36 PM, Nick Newman <dilly...@gmail.com> wrote:

On Thursday, November 17, 2016 at 4:39:17 PM UTC-8, melonJS wrote:

Huh? I cannot really see your code properly, but if you take the platformer example, it works properly when walking towards the crates.

Could this be a bug in the ellipse vs polygon collision handling/response ? i must admit i never use it, just using polygons all the time.

Wow, you're right!!

I removed 

this.body.shapes[0] = new me.Ellipse(this.width/2, this.height/2, this.width/1.3, this.height/1.3);

Which was overriding my default created shape. I think there is a bug with the Ellipse collision shape? Now it works fine!! Thank you!!
 

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[Nick Newman]

And.. it's my fault again and I keep blaming the engine. Sorry folks! Thanks for putting up with me =]  

[Jay Oster]

No worries, it is the engine's fault, actually! Known bug: https://github.com/melonjs/melonJS/issues/809

On Thu, Nov 17, 2016 at 6:30 PM, Nick Newman <dilly...@gmail.com> wrote:

And.. it's my fault again and I keep blaming the engine. Sorry folks! Thanks for putting up with me =]  

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