attach callback to whenever a sprite is rendered

[NessEngine]

Well title pretty much summarize it..

 

I want to attach a callback that will be called every time a certain sprite is rendered. What's the best (pixi-friendly) way to do it?

Looking at the code looks like I could override _renderWebGL and _renderCanvas to first do what I want and then call the original function, but that's kinda ugly.

Any ideas?

Thanks. 

[ivan.popelyshev]

PIXI friendly way is to make your own PIXI.Container and put Sprite inside.

 

Are you sure that you want to intercept the rendering process? There's updateTransform() thing that executed before renderer starts it work, to calculate matrices based on parent matrix, position, rotation and scale. That's how pixi-spine handles it autoUpdate:

function MySprite() {    this.autoUpdate = true;    PIXI.Sprite.apply(this, arguments);}MySprite.prototype = Object.create(PIXI.Container);MySprite.prototype.constructor = MySprite;MySprite.prototype.updateTransform = function() {   PIXI.Container.prototype.apply(this, arguments);   if (this.autoUpdate) { /* DO STUFF WITH this.children[0] */ }}//and that's how you create itvar spr = new MySprite();spr.addChild(new PIXI.Sprite(texture));

Dont forget that updateTransform() is called only for object which has ".visible == true". Render methods are called for objects which have both ".visible==true" and ".renderable==true".

[NessEngine]

sounds good, but will it always be called? or are there conditions where matrices are stored in cache and it will no longer be calls as long as the sprite remains static?

 

thanks!

[ivan.popelyshev]

Always. Unless:

1) you set visible=false there or in one of the parents.
2) Its inside other smartass container which overrides updating or rendering process. ParticleContainer does that for performance.

[NessEngine]

Well looks like its working.

 

Thanks a lot!

EDIT: PS it appears to be working even if I do visible = false, but that's OK for me. (as a test I override this function on a single sprite and not in the prototype, and I see that its keep getting called even after setting its visible to false)

[ivan.popelyshev]

Current pixi philosophy is "Container is the man". Some facts from container's life:

 

1) All containers has a transform that will be applied to all children using updateTransform()

 

2) If there are filters, PIXI.Container can render all its children to separate buffer, and then apply filters.

 

3) PIXI.Container bounds are determined by children bounds, it combines all rects inside.

 

4) PIXI.Sprite is a container, but its bounds are determined by its texture. It actually treats itself as a background for its children.

 

5) PIXI.ParticleContainer is smartass thing that handles 100k sprites. But they must have the same texture and container decides the rendering process.

 

6) container.cacheAsBitmap = true; will create temporary texture, render children to it and stop all rendering and updating process for them. Everything will be static unless you specify =false; in that property.

 

Summary: PIXI.Container is very powerful thing. Its worse than Entity/Component architecture but give it some time, it will evolve.