Where are my vertex colors?

I want to use vertex colors in my shader. After spending a few minutes reading JSON Model format 3.0 I made this model manually:

{
    "metadata":
    {
    "sourceFile": "",
    "generatedBy": "3ds max ThreeJSExporter",
    "formatVersion": 3,
    "vertices": 4,
    "normals": 0,
    "colors": 4,
    "uvs": 0,
    "triangles": 2,
    "materials": 1
    },

    "materials": [
    {
    "DbgIndex" : 0,
    "DbgName"  : "dummy",
    "colorDiffuse"  : [0.5, 0.25, 0.25],
    "vertexColors" : true
    }

    ],

    "vertices": [-100,-100,0, 100,-100,0, -100,100,0, 100,100,0],

    "normals": [],

    "colors": [6808406,16777215,5197746,5197746],

    "uvs": [[]],

    "faces": [128, 0,1,2, 0,1,2, 128, 2,1,3, 2,1,3]

}

However it doesn’t work with my shader:

"varying vec4 vColor;",
"void main() {",
"   vColor = vec4(color, 1.0);",
"   gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);",
"}"

Strangely color is always solid white. I also tried a simple box exported by ThreeJSExported with “Export vertex colors” checked. Doesn’t work either. So what shall I do?

BTW is it possible to include an alpha component in vertex colors?

[dacre-denny]

@donmccurdy thanks for your prompt response! It was an error on our part - color was being multiplied by 255 in our vertex data

[donmccurdy]

@mooce for help and questions, could you post to the forum? It will also help to include details such as your code or source model (if any) for us to guess why your colors might have large values. 😃