VRC Texture Painter

Paint textures directly on your avatar in the Unity Scene view, the way Blender’s Texture Paint mode works. It has hard and soft brushes, a blur brush, a colour blend brush, an eraser, a gradient line tool, and a Photoshop style layer stack. Painting works in 3D, so strokes stay continuous across UV seams and land correctly on mirrored or overlapping UVs and on any UV channel.

Built for VRChat avatar creators on Unity 2022.3.22f1 (DX11, Built-in render pipeline, Linear colour space). The tool is editor only. It adds no components to your avatar and never touches your material assets while you paint, so uploads are unaffected.

Install

With the VRChat Creator Companion: open the package listing and click Add to VCC, or add https://toffelskater.github.io/VRC-Texture-Painter/index.json under Settings > Packages > Add Repository. Then add VRC Texture Painter to your project under Manage Project.

Manually: download the .unitypackage or .zip from the latest release. Import the .unitypackage, or unzip the .zip into your project’s Packages/com.vrctexturepainter.tool folder.

Then open Tools > VRC Texture Painter.

Quick start

1. Select the avatar’s body mesh (or right click the Skinned Mesh Renderer component and choose Paint Texture). To paint masks instead, use the Mask Painter tab (see Mask painter).
2. In the window, click Use Selection, then check the material slots, the texture property (usually _MainTex) and the UV channel (usually UV0).
3. Click Start Painting. The current texture becomes the Base layer, and an empty Layer 1 is added above it for painting.
4. Paint in the Scene view with the left mouse button. Alt + drag still orbits.
5. Use Export PNG… to write the flattened texture and assign it to the material, or Overwrite Source to replace the PNG the material uses. When the slot has no texture yet, Create Texture… takes the place of Overwrite Source: it saves a new PNG and assigns it, and from then on Overwrite Source updates that file. To skip the save dialog, drag a folder from the Project window into Output Folder: Export PNG and Create Texture then save straight into it, named after the material and texture property (for example Body_EmissionMask.png), and add a number instead of replacing an existing file. The folder is remembered per project.
6. Save writes a .mtpaint project with every layer, so you can keep editing later.

Brushes

Tool	Key	What it does
Hard	3 / Num 1	Solid, antialiased disc
Soft	4 / Num 2	Smooth falloff; Hardness sets the size of the solid core
Blur	5 / Num 3	Moves each texel towards the average of its neighbourhood. Blur Size sets the kernel width
Blend	6 / Num 4	Blends the colours under the brush into a smooth, seamless transition. Blend Width sets how long the gradient is; Flatten mode pulls the area towards one average colour instead
Eraser	7 / Num 5	Removes paint from the layer (makes it transparent)
Gradient	8 / Num 6	Drag from one point to another to paint a straight line of the set Width, coloured from the first colour at the start to the second colour at the end
Custom	9 / Num 7	A brush whose dabs take the shape of a black and white texture (the Brush Tip), for splatter, chalk, fur strands or patterns. Rotation keeps every dab at the Angle, turns the dabs with the stroke, or turns each dab randomly. Erase erases in the shape of the tip
Stamp	0 / Num 8	Places one black and white texture where you click, for symbols, logos and patterns. Keep the button down to move it; it is placed when you release

Hard, soft, eraser and custom strokes use Opacity the way Photoshop does: a stroke never builds up past its opacity, however often you go over the same spot. Blur and blend use Strength per dab.

The Gradient works like the line tool in Krita, but fills the line with a gradient instead of one colour. Press where the line starts and drag to where it ends. The line updates on the model while you drag and is painted when you release. Hold Shift to snap its angle to 15° steps, and press Esc to cancel it. The gradient only covers the line, not the whole texture, and the line has flat ends. Hardness softens its long edges, and Mix Colors In sets how the two colours blend. The line is always measured on screen, so Falloff Shape and pen pressure do not apply to it.

Six stamps come with the painter: star, heart, sparkle, moon, paw and flower. Click one under Defaults to use it; the Stamp starts with the star. They work as brush tips for the Custom brush too, for example sparkles with random rotation.

Custom and Stamp use any texture in the project as their shape: white paints, black leaves the surface as it is, grey paints partly, and transparent parts never paint. Turn on Invert for black symbols on a white or transparent background. Size is the longer side of the texture on screen, Angle turns it counterclockwise, and the texture is always laid flat on the screen, so Falloff Shape does not apply. Occlusion, backface culling, normal falloff and mirror work as usual (the mirrored copy is a mirror image).

The Blend brush reads the colours as they were when the stroke started. Dragging it across a border blends that border into a gradient without carrying colour along the stroke (no smearing), and going over the same spot again only brings it closer to the finished gradient.

Mix Colors In (Blur, Blend and Gradient) decides how colours are averaged:

• Perceptual (default, OKLab) gives even transitions without dark, muddy midpoints.
• Linear mixes like light and gives brighter midpoints.
• Srgb uses the stored texture values, like Photoshop.

Stroke options

• Falloff Shape. Projected is a circle on screen that paints everything visible inside it. Sphere paints only surfaces within a 3D ball around the point under the cursor, which is handy for fingers, ears and hair cards that sit close together.
• Occlusion only paints surfaces visible from the camera.
• Backface Culling skips faces that point away from the camera.
• Normal Falloff fades paint on surfaces seen at a grazing angle, which prevents stretched streaks.
• Mirror also paints the mirror image across the avatar root’s X, Y or Z axis.
• Pen pressure can control size and/or strength (Windows Ink tablets).

Layers

• Blend modes: Normal, Darken, Multiply, Color Burn, Lighten, Screen, Color Dodge, Add, Overlay, Soft Light, Hard Light, Difference, Subtract.
• Per layer: opacity, visibility, and lock transparency. With lock transparency on, painting changes colour only where the layer already has pixels.
• Buttons: New, Duplicate, Delete, Merge Down, Fill (with the brush colour), Clear, and Import Image (PNG/JPG/TGA from anywhere, or any texture inside the project).
• Drag rows to reorder. Double click a name to rename the active layer.

Every paint stroke and layer operation is on Ctrl+Z / Ctrl+Y through Unity’s normal undo. History is kept on the GPU, 30 steps by default.

Mask painter

The window has two tabs. Texture Painter is the colour painter described above. Mask Painter paints the mask textures of a shader.

1. Pick the renderer and material slots as usual.
2. Under Mask Texture, pick one of the shader’s texture slots and its UV channel. The Texture Painter only lists the main texture (_MainTex, or the slot the shader marks as [MainTexture]), lilToon’s _Main2ndTex and _Main3rdTex, and Poiyomi decal textures. Every other slot, such as Poiyomi’s _EmissionMask, Standard’s _DetailMask or a normal map, is listed here. A slot without a texture starts black.
3. Click Start Painting Mask and choose what to paint: R, G, B, White or Black.

Masks mix instead of replacing each other. R, G and B each change only their own channel, so painting red and then green over the same spot gives red + green (yellow), and both masks are kept. White raises every colour channel, Black clears every colour channel. Alpha is never painted and stays as it is.

Tool	Key	On a mask
Hard / Soft	3 / 4	Move the selected channel(s) towards 1 (Black: towards 0), up to the opacity
Blur	5	Softens only the selected channel(s)
Eraser	7	Takes the selected channel(s) back to 0
Gradient	8	A line from the mixed R / G / B colour at its start to black at its end
Stamp	0	Stamps a black and white texture into the selected channel(s)

• The Gradient has its own R, G and B toggles, which mix its start colour. Turn on R and G for a yellow to black gradient, for example. Only the mixed channels change, so masks in the other channels stay.
• Fill, Clear and Invert change the selected channel(s) on the whole mask.
• Show Mask On Model also puts the mask in place of the material’s main texture, so you can see where it is painted even when the effect it drives is off.
• Masks have no layer stack. Strokes go straight into the mask texture, with undo.
• Export, Overwrite Source and projects work like in the texture painter.
• Each tab keeps its own brush settings and its own session. Both can be open at the same time, but only the visible tab paints and shows its preview on the model. A dot on a tab means it has a session open.

Controls

Input	Action
Left drag	Paint
[ / ]	Smaller / larger radius
Shift + [ / ]	Less / more strength
Ctrl + scroll	Radius
Ctrl + Shift + scroll	Strength
3 – 9, 0 or Num 1 – 8	Hard, Soft, Blur, Blend, Eraser, Gradient, Custom, Stamp
Shift while dragging a gradient	Snap the line to 15° steps
C or Num 0	Pick the colour under the cursor
Right mouse + WASD / QE	Fly through the scene as usual; painting keys are ignored meanwhile
Esc	Cancel the current stroke
Ctrl + Z / Ctrl + Y	Undo / redo

The painting keys avoid everything Unity 2022.3 binds in the Scene view by default (Q–Y tools, WASD/QE fly mode, 2 for 2D mode, F, V, X, Z, H, L, P). Numpad keys need Num Lock on. With it off, Windows sends arrow keys and Delete instead, and those move the camera or delete the selection. While painting, Unity’s transform tools stay switched off, so an accidental Q (View tool) can’t turn left drag into panning.

Several textures and UV channels on one material

Some avatars show different textures through different UV channels on the same material. A common setup is a Poiyomi body material whose main texture covers the body on UV0 while a decal draws the face texture through UV2. In Blender the head’s UV0 and the body’s UV2 are then left empty (collapsed).

Add one entry per texture under Textures before you start painting. Poiyomi decals on the material are offered as + Decal buttons, with their UV channel already filled in. An info box also tells you when triangles would not receive paint and which UV channel they use instead.

While painting:

• Each triangle is painted into the first texture in the list whose UV channel has a layout for it, so body strokes go into the body texture and face strokes into the face texture.
• A stroke over the neck paints both textures. Blur and Blend mix colours across the border.
• The layer stack is shared. New, duplicate, delete, merge, fill, opacity, blend mode and undo apply to every texture. The layer list shows one thumbnail per texture.
• Import Image asks which texture the image belongs to. Export and Overwrite Source work per texture.

Decals must sit at their default placement (position 0.5 / 0.5, scale 1, rotation 0, no tiling). Otherwise the setup shows a warning, because strokes would land offset from where the decal is drawn.

How UV-aware painting works

Most in-editor painters ray cast the cursor to a single UV coordinate and stamp a circle into the texture. That approach breaks at UV seams, distorts on stretched islands, and misses the other copies of mirrored or stacked UVs. This tool works in reverse:

1. The posed mesh is baked in world space (skinning and blend shapes included).
2. Each dab rasterizes the mesh into texture space on the GPU. Every texel it covers knows the 3D surface point it belongs to.
3. That 3D point is tested against the brush, projected on screen or as a sphere, with occlusion and facing checks.

So a stroke crossing a seam paints both islands, since both sides are near the brush in 3D. A texel shared by several faces (mirrored or overlapping UVs) takes paint from whichever face is under the brush, and brush size stays constant however the UVs are scaled.

The blur and blend brushes read colours from a small capture of the model around the brush. That capture is continuous across seams, so blurring over a seam smooths it instead of leaving a line.

Seam padding extends painted colour a few texels past island borders in the preview and the exported file, so mip maps and bilinear filtering don’t show thin lines along seams. The default is 16 texels, and you can change it under Output.

Notes and limits

• Pose. The mesh is re-baked automatically when you pose the avatar, move it or change blend shapes, but not during a stroke. Re-bake Pose forces a refresh.
• Base layer quality. When the source texture is a PNG, JPG or TGA, the base layer is read from the original file at full quality. Other formats (PSD, TIFF, EXR) are read from the imported texture, which may be compressed or downscaled by its import settings.
• Occluders. Only the painted renderer counts for occlusion. Other meshes, such as clothing on a separate renderer, do not block paint.
• UVs outside 0–1 are painted wherever the texture’s wrap mode samples them. Repeat wraps them back into the texture, so islands moved to other tiles (Poiyomi UV Tile Discard, tiling) and islands crossing a tile edge work. Mirror and Mirror Once reflect them. Clamp only paints inside 0–1, since outside it the texture just shows its edge. The wrap mode comes from the texture’s import settings, and you can override it with UV Wrap before starting. A triangle spanning more than 16 tiles is only painted in its first 16. UDIM (a separate texture per tile) is not supported.
• Double application. Where overlapping UV copies are both under the brush at the same time, blur and blend apply twice to those texels.
• Precision. Layers are 8 bits per channel. Very light blur passes use dithering, so they still converge.
• Embedded materials. Materials inside an FBX cannot be assigned automatically. Extract them first (Materials > Extract Materials).
• Autosave. Scripts reloading or entering Play mode discards GPU data, so the session is auto-saved to Library/MeshTexturePainter/ and restored when you return to Edit mode.
• VRAM. Each layer at 4096×4096 uses about 64 MB, and each undo step the same. The history drops old steps when it passes 2 GB.

Self test

The GitHub repository has a GPU test suite in Assets/MeshTexturePainterTests, which is not part of the installed package. It covers brush placement, seams, padding, blur and blend, occlusion, blend modes, gradients, masks, multiple textures, undo, save/load, export and skinned meshes. Run it headless in the repository’s Unity project. It quits Unity when done and returns exit code 0 on success:

Unity.exe -batchmode -projectPath <repository> -executeMethod MeshTexturePainter.Tests.MTPTests.Run -logFile test.log

Search the log for MTPTEST. The suite creates and deletes temporary assets, so don’t run it in an avatar project.

Project files

.mtpaint files hold a JSON header (target renderer, UV channel, slots, texture property, padding, texture or mask project) and one PNG per layer. A mask project always opens in the Mask Painter tab. You can store them inside or outside Assets. When you open a project, it finds its renderer again by object id or hierarchy path. If that fails, select the renderer first.