How to update polyline colors dynamically (Cesium 1.4/Master)?

CesiumJS
1

Hi!

I have a polyline and I need to gradually fade it (or do some other color/alpha manipulations over time)

So for example I have this polyline (can be run in SandCastle)

2

Nik, the only way to do this is currently is to recreate the primitive for each update. It’s never been possible to do what you describe with per-vertex colors. If the line were a solid color, it would be possible using instance attributes.

3

It was definitely possible in versions like b10 that we were using before. Based on multiple colours of a line we were able to control opacity of different parts of it in realtime without recreating a line.

Please, refer to this video as an example of the case http://vimeo.com/51892033

Slightly shortened piece of old code that did the thing above (applied for each existing line)

AttacksRendererService.prototype._updateLineAlpha = function (line) {

 var i;

 var len = line._actualLength;

 var ttl = line._death - Date.now();

 var age = ttl / this.settings.atkLifetime / 1000;

 var percentage = 1 - age;

 for (i = 0; i < len; i = i + 1) {

   line._colors[i].alpha = 0;

   if (i === parseInt(percentage * len, 10)) {

     line._colors[i].alpha = this.settings.atkMaxAlpha;

   }

 }

 // This is just a hack to call makeDirty since it's a hidden method

 // It doesn't actually update the color

 var c = line.getColor().clone();

 line.setColor({red: 1, green: 1, blue: 1, alpha: Math.random()});

 line.setColor(c);

};

4

can i see live demo ?thanks?