[docs] scene look: the post-processing stack

A new page for layer 1 of the look model, written for someone building a look
rather than reading the architecture:

- adding and ORDERING effects, and what the "Effects: N, passes: M" line is for
  (most effects merge into one fullscreen shader; ambient occlusion needs its own
  pass and splits the run wherever it sits, so it belongs at one end).
- ambient occlusion's parameters, which had no controls at all before this
  release, including why Quality and Half resolution default to Auto.
- LUT grading, and that the file travels to peers and inside a .tpscene by itself.
- tone mapping taking over from the renderer's curve, so nothing is graded twice.
- the visibility split, stated plainly: the look renders for EVERYONE because it
  is part of the scene; what is local is your right to switch it off. Turning an
  effect off in the stack changes it for everybody, and the page says which
  control does which.
- the limits, unvarnished: no post in VR, the camera PiP shows the plain image,
  depth-less sprites and particles are unaffected, GLTF cannot carry it, and the
  mobile-driver failure with the one switch that fixes it.
- what happens to an effect from a NEWER version (kept, shared, marked
  unsupported, never quietly deleted).

camera.md's view-mode table now says these are SHADING modes and links across —
that page previously implied Shaded + AO was the whole story, and it is the place
someone looks when the scene's look is not what they expected. index.md gains the
feature line; mkdocs.yml the nav entry after Shader Nodes.

Author: AlexZ005

docs/camera.md

@@ -28,6 +28,12 @@ Three per-device render modes under **Viewport — this device**:
 
 Ambient occlusion and wireframe are **desktop-only** and never shown to peers. AO detail follows your shadow-quality setting (below), so lowering shadow quality also lightens the AO cost.
 
+These are SHADING modes — they are not how you see the scene's own look. A
+[scene look](post-processing.md) renders for everyone in every mode except Wireframe, and
+you switch it off for yourself under **Overrides — this device**. If the scene sets its own
+ambient occlusion, **Shaded + AO** switches off and says so: the scene's setting is used
+instead of yours.
+
 The **Show light helpers** toggle here draws icons for lights so you can see where they are.
 
 ## Camera lens

docs/index.md

@@ -29,6 +29,7 @@ You build scenes from primitives, imported models and packs, wire behavior with
 - [Mesh Editing](mesh-editing.md) — vertices, edges and faces: extrude, bevel, knife, loops and mirroring.
 - [Snapping](snapping.md) — line things up: grid steps, surfaces, and snapping onto real geometry.
 - [UV & Textures](uv-editor.md) — unwrap a model, paint on it, and give parts of it their own materials.
+- [Scene Look (Post-processing)](post-processing.md) — grade the finished frame: ambient occlusion, colour, bloom, grain. Saved with the scene and shared with everyone.
 - [Animation](animation.md) — keyframe clips with a timeline, curves, markers and onion skin.
 - [Physics & Simulation](physics.md) — mass, joints, dropping and throwing objects.
 - [Terrain & Sculpting](terrain.md) — add ground and shape it with a brush.

docs/post-processing.md

@@ -0,0 +1,115 @@
+# Scene Look (Post-processing)
+
+Grade the finished frame. A **scene look** is a stack of screen-space effects — ambient
+occlusion, colour grading, bloom, vignette, film grain, pixelation — applied over the
+whole viewport after the scene is drawn.
+
+The look is **part of the scene**. It replicates to everyone in the session the moment you
+change it, it is saved with the file, and it undoes like any other edit. Nobody has to
+switch anything on to see what you made.
+
+## Opening it
+
+**Configure Scene ▸ Post-processing** — or right-click the viewport and choose
+**View ▸ Post-processing…**, which opens the panel straight at that section.
+
+## Building a look
+
+Press **+ Add effect** and pick one from its family:
+
+| Family | Effects |
+|---|---|
+| Ambient occlusion | Ambient occlusion |
+| Colour grading | Tone mapping, Hue / saturation, Brightness / contrast, LUT |
+| Stylize | Dot screen |
+| Camera FX | Bloom, Vignette, Film grain, Chromatic aberration, Pixelation, Scanlines |
+| Anti-aliasing | SMAA |
+
+Each row has a grip to **drag it up or down**, a checkbox to switch it off without losing
+its settings, and a **✕** to remove it. Click a row's name to open its parameters.
+
+**The order matters.** The stack runs top to bottom over the frame, so grading placed
+before a vignette darkens differently than grading placed after it. Drag to rearrange, or
+use the ↑ ↓ buttons.
+
+### What the "passes" line means
+
+Under the enable checkbox you will see something like:
+
+> Effects: 4, passes: 2 (2 merged into a shared pass)
+
+Most effects are combined into a **single fullscreen shader**, so eight of them usually
+cost far less than eight times one. Ambient occlusion is the exception — it needs a pass of
+its own, and it splits the run wherever you place it. That line is there so you can see the
+cost of what you are building; if you care about performance, keep the AO entry at one end
+of the stack rather than the middle.
+
+## Ambient occlusion
+
+Soft contact shadows where surfaces meet. Its parameters had no controls at all before this
+release:
+
+- **Radius** — how far a surface looks for things that occlude it, in world units.
+- **Intensity** — how dark the occlusion gets.
+- **Falloff** — how quickly the effect fades with distance.
+- **Quality** and **Half resolution** — both default to **Auto**, which follows each
+  viewer's own shadow-quality setting, so everyone keeps their own performance trade-off.
+  Pin them when the look matters more than the frame rate.
+
+If your scene sets its own ambient occlusion, the personal **Shaded + AO** button in
+**View** switches off and says so — the scene's setting is used instead. Two AO passes would
+double every contact shadow and cost twice as much.
+
+## Colour grading with a LUT
+
+A **LUT** (lookup table) is the standard way to move a grade between tools. Put a `.cube`
+file — or a LUT strip image — in the [Explorer](explorer.md), then pick it in the LUT
+effect's **LUT file** row.
+
+The file is shared with your peers automatically. Anyone who does not have it asks for it,
+so people who join later get the grade too, and it travels inside a saved
+[`.tpscene`](saving.md).
+
+**Smooth interpolation** (tetrahedral sampling) is slower but avoids banding on small LUTs.
+
+## Tone mapping
+
+Tone mapping decides how bright values are compressed into what your screen can show.
+While a **Tone mapping** effect is in the stack it takes over from the renderer's own
+curve, so the image is never mapped twice — pick the curve you want (AgX, ACES Filmic,
+Neutral, Reinhard, Cineon, Uncharted 2) and set its white point and middle grey.
+
+## Seeing it, or not
+
+The look renders for everybody. What is local is your right to switch it off:
+
+- **View ▸ Overrides — this device** has a **Scene look (post-processing)** checkbox. Turn
+  it off if your machine struggles, or if an effect is uncomfortable to look at. Your peers
+  still see the scene as its author made it.
+- **Wireframe** skips post-processing entirely — it is a diagnostic view.
+- Turning an effect off in the stack, or unticking **Scene look enabled**, changes it *for
+  everyone* — that is scene data, not a personal setting.
+
+## Limits worth knowing
+
+- **Post-processing does not run in VR.** The effects are skipped in a headset; objects
+  still look the same, and materials made with the [Shader Graph](shader-graph.md) are
+  unaffected.
+- **The camera preview inset (PiP) shows the plain image**, without the look.
+- **Sprites, billboarded avatar photo cards and particles** do not write depth, so effects
+  that read depth do not affect them. A strong stylize effect makes that more visible than
+  ambient occlusion ever did.
+- **A GLTF export does not carry the look** — glTF has nowhere to put screen-space effects.
+  The app tells you when you export. Save a **Scene (`.tpscene`)** to keep it.
+- On some mobile GPUs fullscreen effects are mis-rendered by the driver: the viewport can
+  freeze on a stale frame while you move. If that happens, switch the scene look off in
+  **View ▸ Overrides**.
+- Very old browser builds have a shader bug with fullscreen effects; the app detects them,
+  skips the look and explains once.
+
+## Effects that come from a newer version
+
+If someone using a newer build adds an effect this one does not know, it is shown in the
+list as **unsupported** and left completely alone — it is still saved, still shared, and
+still there for people whose version does understand it. Nothing you do to the rest of the
+stack deletes it.

mkdocs.yml

@@ -14,6 +14,7 @@ nav:
     - UV & Textures: uv-editor.md
     - Shader Graph: shader-graph.md
     - Shader Nodes: shader-nodes.md
+    - Scene Look (Post-processing): post-processing.md
     - Animation: animation.md
     - Physics & Simulation: physics.md
     - Particle Effects: particles.md