draw text "on screen"

[farfromrefug]

Today i have this working with a deck.gl

Now i would like to achieve something more like this. By like that i mean drawing texts "onscreen" (fixed font size not depending on "distance" to camera). And maybe even draw them at a "z" position depending on the camera view. That way i could draw them let s say at 3000m. But if the camera view dont "see" 3000m i could draw them at a lower z position.

As anyone any idea on how to achieve that in deck.gl?

[Pessimistress]

You can calculate the on-screen positions using viewport.project and then render the texts in an OrthographicView on top of the MapView.

See using multiple views

[farfromrefug]

@Pessimistress i am really sorry to bother you but i am not really managing to get this to work. I have update my codepen quite a bit as i understood a lot more things. Still i cant get my "texts" to be "projected" on screen (the main point being to have the same font size whatever the depth position).
I have read somewhere about modelMatrix and that it could be changed at render time? Maybe this could help to "project" lat/lon positions to screen, not sure...

[farfromrefug]

I actually discovered there was a slack community. Better to ask it there.
Thansk

[Pessimistress]

• you need to call project from the viewport of the mainView (input lng/lat output screen coordinates), not the OrthographicView (input screen coordinates output screen coordinates).
• getPositions are only called once unless you invalidate the positions with updateTriggers
• you should listen to Deck's onViewStateChange in which you update currentViewport and call setLayers to update the update triggers. layerFilter is called during the render stage, after layer updates are already finished. See https://deck.gl/docs/developer-guide/custom-layers/layer-lifecycle#layer-lifecycle-stages

[Pessimistress]

Alternatively you can subclass the MultiIconLayer and overwrite the projected y and z in the vertex shader. This would be the most performant approach but requires some knowledge about writing shaders.

[farfromrefug]

@Pessimistress actually yes this is what i thought too and tried. I looked here and tried to change the method in the IconLayer here But i could not get the method to work with the arguments.