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I've created a webgl animation using the scenejs framework. As it'll contain a lot of identical elements, I want to minimize the amount of code used and re-use the elements as much as possible.

Firstly, I've got diskJSON defined as following:

var diskJSON = [{
type: "disk",
radius: 3,
inner_radius: 2}];

When I run the following code with sceneJS, it works fine.

{
    type: "material",

    emit:           0,
    baseColor:      {
        r: 0.3, 
        g: 0.3, 
        b: 0.9
    },
    specularColor:  {
        r: 0.9, 
        g: 0.9, 
        b: 0.9
    },
    specular:       0.9,
    shine:          100.0,




    nodes: [ {
        type: "translate", 
        x:10,
        y:1,
        nodes: [
        {
            type: "translate", 
            z:speedMultiplier*0.8,
            nodes:[{
                type: "disk",
                radius: 3,
                inner_radius: 2
            }]
        },
        {
            type: "translate", 
            z:speedMultiplier*9.8,
            nodes:[{
                type: "disk",
                radius: 3,
                inner_radius: 2
            }]
        },
        {
            type: "translate", 
            z:speedMultiplier*11.64,
            nodes:[{
                type: "disk",
                radius: 3,
                inner_radius: 2
            }]
        },   
        {
            type: "translate", 
            z:speedMultiplier*13.32,
            nodes:[{
                type: "disk",
                radius: 3,
                inner_radius: 2
            }]
        }

        ]
    }
    ]




}

However, when I try to reuse the same diskJSON as defined previously, it only creates one node, instead of 4:

{
    type: "material",

    emit:           0,
    baseColor:      {
        r: 0.3, 
        g: 0.3, 
        b: 0.9
    },
    specularColor:  {
        r: 0.9, 
        g: 0.9, 
        b: 0.9
    },
    specular:       0.9,
    shine:          100.0,




    nodes: [ {
        type: "translate", 
        x:10,
        y:1,
        nodes: [
            {
            type: "translate", 
            z:speedMultiplier*0.8,
            nodes:diskJSON
        },
        {
            type: "translate", 
            z:speedMultiplier*9.8,
            nodes:diskJSON
        },
           {
            type: "translate", 
            z:speedMultiplier*11.64,
            nodes:diskJSON
        },   
        {
            type: "translate", 
            z:speedMultiplier*13.32,
            nodes:diskJSON
        }

        ]
    }
    ]




}

The application will have thousands of these nodes, so having to redefine it every single time seems quite a waste. Is this a problem with scenejs or is this working as intended in regards to Javascript/JSON functionality?

Niklas
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1 Answers1

1

Hey Niklas, you've found a bug in the way SceneJS is parsing the JSON - SceneJS is marking the node objects as visited in a map while it DFS traverses them. So in this case it's marking your "disk" node once as it parses it, then never parsing it again.

Raised an issue here: https://github.com/xeolabs/scenejs/issues/99

Fixing this one as priority.

In the meantime, you could use a factory function:

function newDiskJSON() { return [{ type: "disk", radius: 3, inner_radius: 2}]; };

//...

nodes: [
    {
        type: "translate", 
        z:speedMultiplier*0.8,
        nodes: newDiskJSON()

    // ...

Or use the "instance" node:

http://scenejs.wikispaces.com/instance

cheers, LK

user563124
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