PolyPaint

A vertex colour painting tool for the Unity Editor.

PolyPaint is an Editor tool for painting vertex colours directly onto meshes in the Unity Scene viewport. It's built for artists and technical artists who want to store per-vertex data (masks, blend weights, tints, and more) without needing additional texture maps.

Key Features

• Brush-based vertex colour painting directly in the Scene view
• Paint per-channel (R, G, B, A) individually or in any combination
• Three brush targets: Vertex, Edge, and Face
• Three paint modes: Replace, Add, and Erase
• Fill, Erase All, Clamp, Randomise, and Colour Swap operations
• Vertex colour transfer between two meshes
• Snapshot system for saving and restoring paint data as project assets
• Object Sets for saving and reloading multi-mesh selections
• Undo / Redo history with configurable step limit
• Autosave to snapshot at a configurable interval

Setup

Installing PolyPaint and getting started with painting.

Installation

1. Purchase PolyPaint from the Unity Asset Store.
2. In the Unity Editor, open the Package Manager via Window → Package Manager.
3. Select My Assets from the dropdown, find PolyPaint, and click Import.
4. Once it's imported, open the tool from the menu bar: Tools → PolyPaint.

Requirements

Quick Start

1. Open PolyPaint via Tools → PolyPaint.
2. Select one or more GameObjects with Mesh Filters in your scene.
3. Click the Tool Enabled toggle at the top of the window to activate painting.
4. Choose a colour, brush size, and mode in the Paint section.
5. Click and drag on your mesh in the Scene viewport to paint.

When the tool is enabled, a brush disc and vertex cloud appear in the Scene viewport over your selected mesh. The status bar at the top of the window tells you when painting is ready.

Opening the Tool

You can open PolyPaint two ways:

• From the menu bar: Tools → PolyPaint
• From the Unity Overlay Menu in the Scene view: enable overlays, then find PolyPaint under Custom → PolyPaint

The Scene view overlay is a dockable panel that gives you quick access to the tool toggle, visual options, and undo / redo buttons without needing the main window open.

Targets

Selecting and managing which meshes to paint.

The Targets section shows how many meshes and vertices are currently selected for painting. PolyPaint paints on any selected GameObject with a Mesh Filter component.

The first time you paint on a mesh, PolyPaint creates a unique instanced copy so only that object is affected. Other objects sharing the same source mesh stay unchanged. This instance is saved to your scene and is what all painting, snapshots, and mesh operations work against.

Options

Object Sets

If you regularly paint across the same group of objects, save your current selection as an Object Set asset using Save Selection. You can then restore that exact selection at any time with Select Objects.

Show

Viewport visualisation options.

The Show section controls what's visible in the Scene viewport while you're painting. These options help you see your vertex colour data clearly as you work.

Viewport Options

Vertex Cloud

The Vertex Cloud shows coloured dots in the Scene viewport representing vertex positions and their current colour values. It gives you a live preview of your painted data without switching materials.

Paint

Brush settings, paint modes, and colour channels.

The Paint section contains all your brush controls.

Mode

The brush works in one of two modes. Vertex Paint authors per-vertex RGBA colour data, which your shaders can use for tinting, masking, baked AO, wind, and more. Normals authors per-vertex normals and edge topology, so you can harden or smooth shading directly in Unity without returning to your 3D application.

Shared Vertices

When a mesh is exported from a 3D application, smooth edges share a single vertex between all adjacent faces. Hard edges work differently. The vertex is split into multiple copies stacked at the same world position, one per adjacent face, so each face can carry its own outward-facing normal. In the scene view this looks like a single vertex, but there can be several hidden beneath it.

PolyPaint's Normals brush can do this splitting and merging for you. Hardening an edge separates those stacked vertices and increases vertex count. Smoothing an edge merges them back into one and lowers it. How this affects Vertex Paint is covered in the panes below.

Actions

Mesh-wide colour operations.

The Actions section gives you operations that apply across all vertices on your selected mesh(es) at once, rather than painting by hand. The available actions depend on the current Paint Mode. The Mesh Management buttons at the bottom of the panel are always shown.

Mesh Management

Snapshot

Saving and restoring vertex colour data as project assets.

The Snapshot system lets you persist vertex colour data to a Snapshot asset in your project. You can then apply that data back to any matching mesh at any time, even across different scenes, using a configurable world-space distance threshold to match vertices.

Source

Save and Apply

Autosave

History

Undo and redo vertex colour changes.

The History section gives you undo and redo for paint operations. PolyPaint manages its own undo stack independently from Unity's built-in undo system.

Limitations

Object Sets

Save and restore multi-mesh selections as reusable assets.

An Object Set is a ScriptableObject asset that stores a list of scene objects by their hierarchy path. Save your current selection to an Object Set and restore it at any time, even across sessions.

Creating an Object Set

1. Select the objects you want to save in the scene.
2. In the Targets section, click Save Selection.
3. Choose a save location in your project. The asset is created and automatically loaded into the Targets section.

Using an Object Set

Assign an Object Set to the Object Set field in the Targets section, then click Select Objects to restore the selection. Any objects that no longer exist in the scene are skipped with a console warning.

Creating via Menu

You can also create Object Set assets directly from the Project window via Create → PolyPaint → Object Set.

Snapshots

The Snapshot ScriptableObject asset.

A Snapshot is a ScriptableObject asset that stores a list of vertex world positions and their associated colours. It's a portable, persistent record of your vertex colour data that lives right in your project.

What Gets Stored

Each entry in a Snapshot stores:

• World Position - The position of the vertex in world space at the time of saving.
• Colour - The vertex colour as a Color32 value (RGBA, 0–255 per channel).

Creating a Snapshot Asset

You can create Snapshot assets two ways:

• From the Snapshot section in the PolyPaint window using the New button.
• From the Project window via Create → PolyPaint → Vertex Colour Snapshot.

Frequently Asked Questions

Common questions about PolyPaint.

General

Does PolyPaint work with URP, HDRP, and the Built-in Render Pipeline?

Yes. PolyPaint is an Editor-only tool that modifies vertex colour data directly on meshes. It's render pipeline agnostic. That said, your shader needs to read and use vertex colours for the painted data to be visible at runtime.

Does PolyPaint add anything to my build?

No. PolyPaint is entirely Editor-only. No scripts, components, or assets are included in your build unless you explicitly place them there yourself.

Will it work on any mesh?

PolyPaint works on any GameObject with a Mesh Filter component. It doesn't support Skinned Mesh Renderers, terrain, or procedurally generated meshes that don't have a persistent Mesh asset. See the Targets page for more on what qualifies as a valid target.

Painting

The tool is enabled but nothing is happening when I click in the Scene view.

Check the status bar at the top of the PolyPaint window. It'll tell you exactly what's wrong. The most common causes are:

• No GameObject is selected, or the selected object has no Mesh Filter. See Targets.
• The selected mesh uses a transparent material and Include Transparent is disabled. Also on the Targets page.
• You're clicking outside the Scene viewport, or another tool (e.g. the Transform tool) is intercepting input.

My brush is painting but I can't see the colours in the viewport.

Enable Debug Material in the Show section to apply a temporary debug material that displays raw vertex colour values. If your shader doesn't sample vertex colours, the data is still there. It just won't be visible with your regular material.

My redo history disappeared when I painted something after undoing.

That's expected. As soon as you perform a new action after undoing, the redo stack is discarded. If you want a restore point you can always return to, save a Snapshot before starting a paint session. Snapshots aren't affected by the undo stack.

Painting seems slow or the Scene view is lagging.

Try the following:

• Disable Realtime in the Show section. Overlays will only update when the camera is still.
• Reduce the Draw Distance of the Vertex Cloud, or disable it entirely if you don't need it.
• Reduce Max Steps in the History section to keep less undo data in memory.

Normals

Hardening edges increased my vertex count. Is that expected?

Yes, and it's intentional. Hardening an edge splits the shared vertices at that position. Each adjacent triangle gets its own copy carrying a unique outward-facing normal. That's how hard-edge shading works at the mesh data level. Smoothing does the reverse: copies are merged back into one and the count drops. Keep this in mind if vertex budget or draw cost matters for your target platform.

Some vertices are missing from the vertex cloud when I switch to the Normals brush.

Positions where every surrounding triangle is already coplanar (within about 5°) are hidden from the Normals brush cloud. Hard and smooth shading produce indistinguishable results at those positions, so the tool omits them to reduce noise. The brush, Fill Hard, and Fill Smooth on the Actions page also skip them automatically.

Fill Hard / Fill Smooth didn't affect some areas of my mesh.

Those areas are likely flat. Positions where all surrounding triangles lie within about 5° of one another have no meaningful shading difference between hard and smooth, so they're intentionally skipped. See Set Shading on the Actions page.

UV seams didn't re-weld when I used the Smooth brush.

That's by design. Vertices that lie on a UV seam carry different texture coordinates and can't share a single vertex even if their normals fully align. The Smooth brush will align the normals at those positions but won't merge the vertices. The UV seam, and any split it implies, is always preserved. This is covered in the Shared Vertices section on the Paint page.

I painted a hard edge - now how do I paint different colours on each side of it?

Switch to Vertex Paint mode on the Paint page and set Shared Verts to Split. With the vertices at that edge now separated, each triangle face has its own copy and the colour brush addresses them independently. You can paint one side, then the other, without either bleeding across.

Meshes

What is an "instanced mesh" and why does PolyPaint create one?

Unity shares mesh data between objects by default. Modifying a shared mesh would affect every object using it. When you first paint on a mesh, PolyPaint automatically creates a unique copy of it (an instanced mesh) so only that specific object is affected. The instanced mesh is saved as part of your scene.

Will my vertex colour data survive if I reimport the source mesh?

Reimporting directly will replace the mesh asset and could overwrite your painted data. Use Re-Import Mesh(es) in the Actions section instead. It pulls in the updated source file while preserving your transform, material, and vertex paint data by matching vertices by world position. Paint on vertices that have moved significantly may be distorted.

Are Re-Import Mesh(es) and Reset Mesh(es) undoable?

No. Both operations clear the undo and redo history entirely, then save the scene immediately. Re-Import Mesh(es) transfers your current vertex paint to the reimported geometry using spatial matching. Paint on vertices that have moved significantly may not transfer accurately. Reset Mesh(es) discards the instanced mesh and restores the original asset with no paint data. Save a Snapshot before using either if you want a rollback option. Both actions are documented on the Actions page.

How do I remove PolyPaint's changes from a mesh entirely?

Use Reset Mesh on the Actions page. This removes the instanced mesh and restores the original mesh asset. It can't be undone.

Object Sets

Autosave stops triggering when I deselect everything in the scene.

Autosave requires an active target. When you're using Current Selection as the source, autosave pauses when nothing is selected. Load an Object Set in the Snapshot section and set it as the source. Autosave will then continue running on that fixed set of objects regardless of your scene selection.

The Snapshot source switched to my Object Set automatically - I didn't change it.

That's intentional. When you deselect everything in the scene while an Object Set is loaded in the Snapshot section, PolyPaint automatically uses the Object Set as the source rather than leaving the tool idle. Selecting objects in the scene switches it back to Current Selection.

Snapshots

Can I apply a Snapshot to a different mesh than the one it was saved from?

Yes. Snapshots match by world position, not by mesh identity. As long as the target mesh has vertices in similar world positions to where the snapshot was recorded, the colours will transfer correctly. Use the Distance threshold to control how strict the matching is. See the Snapshots page for detail on loading and applying.

My Snapshot has fewer points than my mesh has vertices. Is that a problem?

Not necessarily. If a vertex in the target mesh has no nearby point in the Snapshot within the distance threshold, it simply won't be updated. This can be intentional, for example if you only saved a partial paint. Adjust the Distance setting on the Snapshots page if you need wider coverage.

Autosave keeps overwriting data I want to keep.

Make sure you have the correct Snapshot asset loaded before enabling Autosave. If you want to preserve a specific state, save it to a separate Snapshot asset first, then re-enable Autosave pointing at a different one. The full Autosave workflow is on the Snapshot page.

Still not solving your problem?

If your question isn't answered here, head over to the Bugs / Feedback page to report a bug, request a feature, or share your thoughts.

Instruction Booklet

In true old-school fashion, the best way to learn PolyPaint is with its included paper instruction booklet. Try not to crumple the pages.

Bugs / Feedback

Report a bug, request a feature, or share a thought about any of the tools.

Snap Verts to Grid

A MEL script that snaps selected geometry to the nearest grid position in Maya.

Maya allows you to select and snap verts to the grid, but only one at a time or as groups relative to one pivot point. This script snaps all selected verts of a mesh (or multiple) to your grid in 3D space at once. You can select entire objects, as well as individual faces, edges, or groups of verts, and snap them to the nearest grid position - on all axes at once, or just along a specific axis.

This can be useful if you're using the grid for pixel-perfect UVing, or need to precisely align many verts to a grid all at once.

Key Features

• Snaps all selected verts to the nearest grid position in world space, independently
• Works on entire objects, faces, edges, or individual vertex selections
• Snap on all axes at once, or just X, Y, or Z individually
• Grid size derived from Maya's Grid Lines Every and Subdivisions settings
• Settings persist between sessions via Maya optionVars

Download & Setup

Installing the script and adding it to your shelf.

Installation

1. Drag snapVertsToGrid.mel into your Maya scripts folder, e.g. Documents/Maya/2023/scripts/.
2. Open the Script Editor in Maya via Windows > General Editors > Script Editor.
3. In the MEL tab of the Script Editor, type source snapVertsToGrid.mel; and hit the run button (the > icon) to load the script.
4. Still in the MEL tab, type openSnapVertsToGridWindow;, highlight it, then middle-mouse drag it onto your shelf to create a shelf button. Alternatively, just run it from the Script Editor each session.
5. Right-click the shelf button, select Edit, and assign SnapVertsToGrid_ShelfIcon.png as the icon image.
6. In the shelf button's Command field, include both source snapVertsToGrid.mel; and openSnapVertsToGridWindow; so the script is always sourced when you click it.

Requirements

Usage

Snapping verts to the grid.

Input your current grid settings (found in Display > Grid), select the object(s), individual face(s), vert(s), or edge(s), then hit the corresponding button to snap your verts to the nearest grid position along the specified axis.

Grid Settings

The snap interval is calculated from two values that match Maya's display grid.

Snap Buttons

FAQ

Common questions about Snap Verts to Grid.

The verts aren't snapping to the right positions.

Make sure the Grid Lines Every and Subdivisions values in the tool window exactly match what's set in Display > Grid. If those values are off, the calculated snap interval will be wrong. Settings persist between sessions via Maya optionVars, so you only need to update them when you change your grid configuration.

Does it work with my version of Maya?

The script was made and tested on Maya 2023.1. Because it is written in MEL rather than Python, it should work broadly across Maya versions, including Maya LT. Older or newer versions are untested but are unlikely to have issues.

Does the snap operation support undo?

Yes. Each snap is a single undoable action in Maya's undo queue. Press Ctrl+Z to reverse it.

Why do I have to re-source the script every Maya session?

MEL scripts are not loaded automatically on startup. The simplest fix is to include source snapVertsToGrid.mel; in your shelf button's Command field alongside openSnapVertsToGridWindow;. The script is then sourced automatically whenever you click the button. See Download & Setup for the full shelf setup steps.

Does it work on skinned meshes?

Not reliably. The script reads vertex positions in world space using pointPosition -w, which on a bound skinned mesh returns the deformed position rather than the base mesh position. Results on bound geometry may be unpredictable.

Still not solving your problem?

If your question isn't answered here, head to the Bugs / Feedback page to report a bug, request a feature, or share your thoughts.