Callback function from button cannot call node inside array Tweet

[diatom]

New lua scripter here. Forgive my naivete in advance.
I am making a script that will get all the render targets in the scene graph that contain panoramic cameras, and then collect data (position, etc), and save it to a json file.
The gui makes a set of buttons for each pano camera found. One will select the render target node and then update the render viewport.
I am looping through an array (of render target nodes) to create my gui elements. The problem arises when I want to pass index data into the button callback.
The callback function can see global variables, but is not able to retain the value of my index variable (c).
How can I get my callback function to reference an item in an array?
If this cannot work, is there a better way to approach this?

Thanks
Thomas

Code: Select all

-- Make an array of all cameras and their render node names
panoCams = {};
renderTarget = {}; -- render target that contains the pano camera
p=1;
-- Get all the render target nodes in the scene
nodes = octane.nodegraph.findNodes( octane.project.getSceneGraph(), octane.NT_RENDERTARGET, true );
-- Refine the render targets to only those with pano cameras
for i, entry in ipairs(nodes) do
   -- print(entry)
    cam = octane.node.getConnectedNodeIx( entry, 1 );
   -- print(cam, cam.nodeType, octane.node.getNodeInfo(cam))
    if cam.nodeType == 62 then -- CAM_PANORAMIC
        panoCams[p] = cam;
        renderTarget[p] = entry;
     
       -- print(p, panoCams[p], entry.name);
        p=p+1;
    end
end

-----------------------------------------------------------------------------------------

panoGroups = {};
panoCaptions = {};
panoOpen = {};
renButtonProps = {};
gTest = "test";
c = 1;
for index, value in ipairs(panoCams) do
    local i = (index-1) * 4
    print(index,  i, ':', panoCams[index], ':', renderTarget[index].name);
    local camlabel       = createLabel("Pano Camera ".. index);
    local renlabel       = createLabel("Render Target "..renderTarget[index].name);

    print('render target: ', c, renderTarget[c].name);

    -- create a button to show a file chooser
    local renderTargetButton = octane.gui.create
    {
        type     = octane.gui.componentType.BUTTON,
        text     = "Render View",
        width    = 80,
        height   = 20,
        callback =
        -- Select the render target
        function(component, event)   
            print('component: ', component);
            print('select render target: ', renderTarget[1].name);  --  *** HERE is where I'd like the index variable c to go, but it returns nil.
            octane.project.clearSelection();
            octane.project.select(renderTarget[1]);
            --octane.render.restart();
           -- octane.render.start {    renderTargetNode = renderTarget[1] };
        end
    }

   
     -- create a button to show a file chooser
    local loadImageButton = octane.gui.create
    {
        type     = octane.gui.componentType.BUTTON,
        text     = "Image Path",
        width    = 80,
        height   = 20,
    }
   
   -- panoGroups[index] = { camlabel, renlabel, fileChooseButton, loadImageButton };
    panoGroups[i+1] =  camlabel;
    panoGroups[i+2] =  renlabel;
    panoGroups[i+3] =  renderTargetButton;
    panoGroups[i+4] =  loadImageButton;

   
    c=c+1
end


[diatom]

I figured out a workaround. I can pass the index (c) into the callback function by assigning the text property of the button to the index as text, then convert it to a number inside the callback.
Not pretty, but it works.

Code: Select all

 -- create a button to render target to viewport
    local renderTargetButton = octane.gui.create
    {
        type     = octane.gui.componentType.BUTTON,
        text     = tostring(c),
       callback =
        function(component, event)   
            local id = tonumber(octane.gui.getProperties(component).text);
            print('select render target: ', renderTarget[id].name);
        end


I'll post a working version of this when it is finished.
Thomas

[jobigoud]

If you assign `c` or `renderTarget[c]` to a local variable inside the loop it should be captured by the callback closure.

[diatom]

Thank you jobigoud!
That worked.
Importantly, the variable has to be local AND
you must return a function that contains that variable to create the closure.

Code: Select all

local id = c; -- stored the global int c in the upvalue id
octane.project.select(renderTarget[id]); -- Access the global array renderTargetusing upvalue [id]

 return function()
           print('select render target: ', renderTarget[id].name);
 end


Thanks for the link to the explanation of closure. Now it all makes sense.

[diatom]

Here is my working version of the script.
It finds all the panoramic cameras in the scene and saves some data : camera positions, names of views, rendered image file paths,
to a json file. I'm using this in another web app, that works with panoramas.

Thomas