CHANGE vertex paint rgb values?

Good catch thank you I missed that. Usually the case for normal maps as well. Yeah I have a list of things I’d like to do including an actual UI.

It seems like the moment I put a math node into the equation to try to convert to linear, it all goes grey whether in Blender or puzzles.

I expounded on your formula a bit.

Hi GlifTek,

GLiFTeK wrote:

however, the code changes the ENTIRE object. not just the one polygon i have painted with a certain Vertex Paint.
is there a way to further specify which faces/vertices get written over (seems they all are).

Yes, in that snippet the vertex color is changed for all vertices at once. You can see that in vertex_colors.js in the prepareExternalInterface function:

...
for (var i = 0; i < vertColor.count; i++) {
    vertColor.setXYZ(i, rgb[0], rgb[1], rgb[2]);
}
...

– this loop iterates through all vertices and the first parameter i in vertColor.setXYZ() is the vertex index. There’s no convenient way to determine which exactly vertices you need to process in order to change colors for a specific face.

So, if your object is low-poly, then you can use a brut-force method – you can just change the color for a single vertex and see if it’s what you want, e.g:

...
vertColor.setXYZ(0, rgb[0], rgb[1], rgb[2]);
vertColor.setXYZ(1, rgb[0], rgb[1], rgb[2]);
vertColor.setXYZ(2, rgb[0], rgb[1], rgb[2]);
vertColor.setXYZ(3, rgb[0], rgb[1], rgb[2]);
...

– and then remember which indices belong to the object area you want to change colors for. After that you can just replace the loop in the snippet with several lines calling vertColor.setXYZ() explicitly for each of those indices.

There’s another approach in case if you need to change a particular distinct vertex color. You can get the current color assigned to a vertex via vertColor.getX(), vertColor.getY() and vertColor.getZ() methods and check if it’s the color that you want to change, for example:

...
var myColor = [1, 0.5, 0.2];
for (var i = 0; i < vertColor.count; i++) {
    var r = vertColor.getX(i);
    var g = vertColor.getY(i);
    var b = vertColor.getZ(i);

    if (r === myColor[0] && g === myColor[1] && b === myColor[2]) {
        vertColor.setXYZ(i, rgb[0], rgb[1], rgb[2]);
    }
}
...

All these solutions are a bit hacky, though. I think it would be more convenient if we could utilize vertex groups for that.

GLiFTeK wrote:

blender’s also doing something unwanted i don’t know how to change where each col map i make with the plus button is a copy of the last, not a new one.

I don’t know how to prevent Blender from doing that either, but there’s a way to fill a whole color layer with the current paint color, it’s some kind of reset:

Hi GlifTek,

GLiFTeK wrote:

could i find the vertex order (which vertex’s are from each square) then use the Face3 to make arrays (face) of each, then do the changes from there?

Yes, but it’s not necessary to use Face3 as a mere container for your data. Face3 holds vertex indices that belong to the face, but you can just store those indices in a simple array and use them to make changes.

Face3 is actually convenient if it’s automatically generated with all relevant data when you convert a mesh from BufferGeometry (which is a default representation, more efficient but not very easy to use) to just Geometry (less optimized, more user-friendly and contains Face3 data). Since you have a very low-poly object there’s no significant drawbacks to prefer Geometry over BufferGeometry.

Unfortunately, there is currently a bug related to vertex colors and the Geometry class in the latest verge3d version. We’ve fixed it but the fix will be available only in the next verge3d update. With that fix you’ll be able to do something like this:

// make the object use Geometry instead of BufferGeometry
var new_geom = new v3d.Geometry().fromBufferGeometry(myObj.geometry);
myObj.geometry.dispose();
myObj.geometry = new_geom;

var RED = new v3d.Color(1, 0, 0);
var GREEN = new v3d.Color(0, 1, 0);

// iterate over all faces and make the 0th face red and the 1st face green
var faces = myObj.geometry.faces;
for (var faceIdx = 0; faceIdx < myObj.geometry.faces.length; faceIdx++) {

    var newColor;
    switch (faceIdx) {
        case 0:
            newColor = RED;
            break;
        case 1:
            newColor = GREEN;
            break;
        default:
            continue;
    }

    faces[faceIdx].vertexColors.forEach(function(vcol) {
        vcol.set(newColor);
    });
}

myObj.geometry.colorsNeedUpdate = true;