# Attribute Tour > The model-viewer attributes with no named prop — loading, reveal, scale, skybox, pan and tap locks, and the AR-only ones — each shown or honestly marked as unshowable. **Site index:** [https://modelviewer.2plot.dev/llms.txt](https://modelviewer.2plot.dev/llms.txt) — every page on this site, as Markdown. **Network index:** [https://2plot.dev/llms.txt](https://2plot.dev/llms.txt) — The 2plot network; start here to discover sibling sites. **Sibling sites:** 13 more in The 2plot network — listed in the site index above. **Sitemap:** https://modelviewer.2plot.dev/sitemap.xml --- ### Why this page exists [Attributes and parity](/attributes-and-parity) argues that the `attributes` dict and `mv_*` wildcards reach every attribute `` has. This page is the evidence: it drives eleven attributes that have **no named prop on `ModelViewer`**, and says plainly which of them you cannot see from a desktop browser. It was written from an audit against `modelviewer.dev`'s own example pages. Those eleven were reachable from this package on the day it shipped and demonstrated nowhere — which is a documentation gap rather than a capability one, and the kind the 1.0.0 review kept finding. ```python # File: docs/attribute-tour/attribute_tour.py from dash import Input, Output, State, callback, html import dash_mantine_components as dmc import dash_model_viewer as dmv from lib.demo_models import ASTRONAUT, MOON_HDR #: Always on, so the model is lit and the ground reads as ground. BASE = {"environment-image": "neutral", "shadow-softness": "0.6"} SCALES = {"1 1 1": "actual size", "0.5 0.5 0.5": "half", "2 2 2": "double"} def build_attrs(no_pan, no_tap, no_prompt, scale, skybox, skybox_height, loading, reveal): """The attribute dict, from the controls. Pure, so it can be tested.""" attrs = dict(BASE) attrs["scale"] = scale attrs["loading"] = loading attrs["reveal"] = reveal # Boolean attributes: present means on. OMITTED when off, never "false" — # "false" is a present value and would leave them on. See the page. if no_pan: attrs["disable-pan"] = "" if no_tap: attrs["disable-tap"] = "" if no_prompt: attrs["interaction-prompt"] = "none" if skybox: attrs["skybox-image"] = MOON_HDR # Only meaningful with a skybox; sending it alone does nothing, which # is why it is nested rather than listed beside the others. if skybox_height: attrs["skybox-height"] = f"{skybox_height}m" return attrs def viewer(attrs): return dmv.ModelViewer( id="at-viewer", src=ASTRONAUT, alt="An astronaut used to demonstrate model-viewer attributes that have no named prop", camera_controls=True, shadow_intensity=1, attributes=attrs, style={"width": "100%", "height": "460px"}, ) CONTROLS = dmc.Stack( gap="sm", children=[ dmc.Text("What the user may do", size="xs", fw=700), dmc.Switch(id="at-pan", label="disable-pan", checked=False), dmc.Switch(id="at-tap", label="disable-tap", checked=False), dmc.Switch(id="at-prompt", label="interaction-prompt: none", checked=False), dmc.Divider(), dmc.Text("The scene", size="xs", fw=700), dmc.Select( id="at-scale", label="scale", data=[{"value": k, "label": f"{k} — {v}"} for k, v in SCALES.items()], value="1 1 1", allowDeselect=False, ), dmc.Switch(id="at-skybox", label="skybox-image", checked=False), dmc.NumberInput( id="at-skybox-height", label="skybox-height (m)", value=0, min=0, max=10, step=1, ), dmc.Divider(), dmc.Text("When it loads", size="xs", fw=700), dmc.Select( id="at-loading", label="loading", data=["auto", "lazy", "eager"], value="auto", allowDeselect=False, ), dmc.Select( id="at-reveal", label="reveal", data=["auto", "interaction"], value="auto", allowDeselect=False, ), dmc.Button( "Reload the model", id="at-reload", variant="light", mt="xs", ), dmc.Text( "loading and reveal only act while a model is loading. " "Press this to see them.", size="xs", c="dimmed", ), ], ) component = html.Div( [ dmc.Grid( gutter="md", children=[ dmc.GridCol(CONTROLS, span={"base": 12, "md": 4}), dmc.GridCol( # The viewer is HERE, in the initial layout, and updates in # place. An earlier version rebuilt it from a callback on # every control, which reloaded the model and reset the # camera each time — so `disable-pan` and `disable-tap` did # work and were impossible to SEE, and the remount reset the # idle timer so `interaction-prompt: none` made the prompt # reappear. The reload is now an explicit button. html.Div(id="at-mount", children=viewer(build_attrs( False, False, False, "1 1 1", False, 0, "auto", "auto" ))), span={"base": 12, "md": 8}, ), ], ), dmc.Code(id="at-readout", block=True, mt="sm"), ] ) _CONTROL_STATE = ( Input("at-pan", "checked"), Input("at-tap", "checked"), Input("at-prompt", "checked"), Input("at-scale", "value"), Input("at-skybox", "checked"), Input("at-skybox-height", "value"), Input("at-loading", "value"), Input("at-reveal", "value"), ) @callback( Output("at-viewer", "attributes"), Output("at-readout", "children"), *_CONTROL_STATE, ) def apply_attributes(*values): """Update the live element IN PLACE — no reload, no camera reset. That is what makes `disable-pan`, `disable-tap` and `interaction-prompt` observable: you can toggle one and immediately try the gesture against the same view. The shim diffs the dict and removes whatever disappeared. """ attrs = build_attrs(*values) rendered = "\n".join(f'{k}="{v}"' if v else k for k, v in sorted(attrs.items())) return attrs, rendered @callback( Output("at-mount", "children"), Input("at-reload", "n_clicks"), *[State(dep.component_id, dep.component_property) for dep in _CONTROL_STATE], prevent_initial_call=True, ) def reload_model(_clicks, *values): """Remount, and ONLY on request. `loading` and `reveal` do nothing to a model that has already loaded, so they need a fresh mount to be observable at all. Doing that on every control change — as this page first did — obscured every other attribute on it. A button makes the reload deliberate and leaves the rest alone. """ return viewer(build_attrs(*values)) ``` The block under the viewer is the attribute dict as it reaches the element, so you can read what each control actually sent. --- ### Reload is a button, not a side effect Most controls here update the live element **in place** — toggle `disable-pan` and you can immediately try a two-finger drag against the same view, with the same camera, and see the difference. `loading` and `reveal` are the exception: they only act **while a model is loading**, so they do nothing to a viewer that has already loaded. That is what the *Reload the model* button is for. The first version rebuilt the viewer on *every* control change, so that `loading` and `reveal` would always be observable. It made everything else worse: toggling `disable-pan` reloaded the model and reset the camera, so the attribute worked and there was no way to *see* that it had — and the remount reset the idle timer, so `interaction-prompt: none` caused the prompt to **reappear** rather than stop. Reported from testing, and the fix is the split above. It is a good example of a demo page being wrong in a way the code is not: every attribute reached the element correctly the whole time. --- ### What you can see from a laptop | Attribute | Values | What to look for | | :-- | :-- | :-- | | `scale` | `"1 1 1"`, `"2 2 2"` | The model gets bigger. Note the shadow scales with it. | | `disable-pan` | present | Two-finger drag (or right-drag) no longer slides the model sideways. | | `disable-tap` | present | A single tap no longer recentres the camera on the tapped point. | | `interaction-prompt` | `none` | The animated hand stops appearing after a few idle seconds. | | `skybox-image` | an `.hdr` URL | The grey background becomes the environment, and the model is lit by it. | | `skybox-height` | e.g. `2m` | Only with a skybox: lifts the horizon so the model sits *in* the scene rather than floating in a sphere. Alone it does nothing, which is why the control is nested under the skybox toggle. | | `loading` | `auto`, `lazy`, `eager` | `lazy` defers until the viewer is near the viewport; `eager` fetches immediately. Watch the network panel, not the picture. | | `reveal` | `auto`, `interaction` | `interaction` holds the poster until you click. | `reveal="manual"` is deliberately absent from the control. It holds the model until `dismissPoster()` is called — an **imperative method**, and 1.0.0 ships no imperative surface, so there is no way to dismiss it from Python. Offering the value would produce a viewer that never reveals, which is a trap rather than a demonstration. --- ### What you cannot see from a laptop These three are real, reachable and **not demonstrable here**. Listing them with their values beats pretending the page covers them: | Attribute | Values | Needs | | :-- | :-- | :-- | | `ar-placement` | `floor`, `wall` | A phone in AR. `wall` anchors the model to a vertical surface — the right choice for a picture frame or a television. | | `xr-environment` | present | A WebXR session on Android. Lights the model with the room's estimated lighting instead of the `environment-image`. | | `ios-src` | a `.usdz` URL | iOS Safari. Quick Look cannot read `.glb`, so an iOS AR path needs a second file. There is no named prop; use `mv_ios_src` or `attributes`. | ```python dmv.ModelViewer( id="viewer", src="/assets/chair.glb", alt="A chair", mv_ios_src="/assets/chair.usdz", attributes={"ar-placement": "floor", "xr-environment": ""}, ) ``` Walk those on [Augmented reality](/augmented-reality) with a real device. A desktop browser will report AR as unavailable and tell you nothing about whether the attributes landed. --- ### Boolean attributes, once more `disable-pan`, `disable-tap` and `xr-environment` are true **by presence**. So: ```python attributes={"disable-pan": ""} # panning is off attributes={} # panning is on attributes={"disable-pan": "false"} # STILL OFF — "false" is a present value ``` The shim removes any attribute that disappears between renders, so building a fresh dict each time — as the callback on this page does — is the pattern that works. `False` and `None` also remove, if you would rather be explicit than rely on absence. The same trap as `paused` on [Animation](/animation), and it is worth meeting twice: it is the single most common way an `attributes` dict does the opposite of what it reads like. --- *Source: /attribute-tour*