Texture Filtering and Seam Padding

A canvas is Closest by default: every texel a sharp square, the pixel art look. Want the texture smooth, or the N64 look? Texture Filtering switches it to Linear or N64 (3 Point), and Seam Padding keeps the UV seams from showing a step at every face, in Blender and in the game engines.

Left to right: Closest, Linear before Seam Padding (a step at every seam) and Linear with Seam Padding.

Texture Filtering

The Filtering row under Paint On, in Setup (3D Viewport and Image Editor), for the texture Paint On names (a greyed out Closest when the model has no texture):

  • Closest (default): every texel a sharp square, the pixel art look.

  • Linear: texels blended into each other. Nothing else to set up, in Blender or in the game engines.

  • N64 (3 Point) (optional): the N64’s own filter, three texels blended a sample, through a node group in the material. In Blender only: the exports carry it as Linear (see In the game engines and the exports).

_images/texture-filtering-row.png

How it works:

  • Every material that samples the texture follows, in this .blend (a material linked from another .blend is that file’s).

  • It reads the Image Texture nodes, so a node you set to Linear by hand in the Shader Editor shows Linear here too (Cubic and Smart too).

  • One undo step.

  • Picking Linear or N64 (3 Point) raises Margin (px) to 4 (Unwrap Options) when it’s lower, for the next unwrap (see The margin for a filtered texture). Closest leaves it as it is.

  • A painted texture whose UV islands sit too close asks first, see UV islands too close for filtering.

  • It stays: the first stroke on a texture that isn’t a canvas yet sets it to Closest (every import comes in on Blender’s Linear, see Painting a texture the model already has), unless you picked its filtering here. Pick it before or after the first stroke and it’s kept.

Seam Padding

Why did Linear show the seams? Quick Unwrap Model gives every face an island of its own, and a filtered texture blends each texel with its neighbours. At the edge of an island the neighbour is a margin texel, and it holds the background, transparent texels or the face’s own colors, never what the model shows across the seam. That’s the step at every seam in the middle picture above.

Seam Padding fills the margin with what the model shows across the seam, so the blend at the edge of an island reads the right color:

  • Automatic, while the texture is filtered (Linear, N64 (3 Point) or a node set by hand). Nothing to click.

  • A Closest texture is never touched: back on Closest, the texture is exactly what your layers make.

  • It’s in the texture: the Image Editor shows it (copies of the island colors around every island), and so do the saved PNG, Export Texture, Image > Save As and every export.

  • It never becomes paint: it isn’t in your layers, the eyedropper on a padded texel picks the color it was copied from, and the texture brought back in as a layer (Import PNG, Paste Image as Layer) leaves it out.

  • The Layers panel says so while it’s on: Seam padding fills the margin / while the texture is filtered.

  • It follows the UVs: after an unwrap or UVs moved by hand it’s laid again (on a big texture it takes a moment, the seams show until it’s there). UVs edited in Edit Mode get it when you leave Edit Mode.

  • Hard Edges (under the Filtering row, off by default): for a texture with the light painted in, where a lit face meets a dark one at a hard edge. On, the padding stops at the edges marked sharp and at the edges sharper than the angle beside it (60° by default, 180° for the sharp edges only), so each face’s margin keeps its own color there and the edge stays crisp.

_images/seam-padding-image-editor.png

Above: the crate after Lay Out Again, on Linear. Every island is ringed with the colors from across its seams, and Layers ends with the note.

Note

Painted in the margin while the texture is filtered? Your layers keep it, but the texture shows the padding there. Back on Closest, your painting shows again.

Note

Texture Dilation grows each island’s own colors into the empty texels around it (see Texture Dilation). While the texture is filtered, the margin next to the islands is Seam Padding’s, and the dilation fills what’s farther out.

What it can’t do:

  • A seam on a texel line is hidden exactly. A diagonal seam (a face edge that cuts through texels) can keep a faint step, much less than without the padding.

  • The islands need 2 texels between them. Closer, a margin texel sits between two islands and both read it, so no fill is right for both (see below).

  • UVs that run past the texture (a texture repeated over the model) get no padding, and the report says so: No seam padding on T_Cube: the UVs run past the canvas.

The margin for a filtered texture

  • At least 2 texels between the islands for a filtered texture: each island needs a ring of its own. 1 (the default) is plenty for Closest.

  • Picking Linear or N64 (3 Point) raises Margin (px) to 4, so the seams stay hidden from far away too (a filtered texture is mipmapped, in Blender and in the game engines). It never lowers it, and you can still type your own.

  • Under 2, the unwrap lays out at 2 anyway while the texture is filtered, and Unwrap Options says so under Margin (px): Filtered: laid out at 2. The report too (Cube: 16 px/m on the 64x64 texture T_Cube (margin 2 for Linear filtering)).

    _images/unwrap-options-filtered-margin.png

  • A bigger margin takes texture space: a model that just fit may need the next texture size (Grow Texture to Fit, see Grow Texture to Fit).

UV islands too close for filtering

The new margin is for the next unwrap. UVs laid out before (at 1, or your own layout) stay where they are, so Pixel Art Studio tells you when they’re too close:

  • The question: picking Linear or N64 (3 Point) on a texture with painting on it, with the islands closer than 2 texels, asks The UV islands are 1 texel apart: seams show under Linear filtering / Lay the UVs out again 4 texels apart? Your painting is kept.

    • Lay Out Again: new UVs at the margin (Quick Unwrap Model’s layout, at the model’s own pixel size), and every layer is carried onto them. One undo step.

    • Not Now (or Esc): the texture stays filtered and the UVs stay as they are.

    _images/texture-filtering-question.png

  • The note in Setup, under the Filtering row, for as long as the texture is filtered and the islands are too close: UV islands 1 texel apart: / seams show while filtered (UV islands touch: when there’s no margin at all), with Lay Out Again under it, the same as the question’s.

    _images/texture-filtering-setup-note.png

  • Object Mode only: from Edit Mode it says Leave Edit Mode first: the UVs are laid out again in Object Mode.

  • A texture with nothing painted yet asks nothing: click Quick Unwrap Model and it’s laid out at the new margin.

Note

Lay Out Again works like Apply New Density in Try Pixel Densities (see Try Pixel Densities): the scene’s pixel density goes to the model’s own too, and a texture that isn’t a canvas yet becomes one first (its own undo step).

In the game engines and the exports

A filtered texture leaves filtered, with mipmaps and with the padding in it. Nothing to set up in the engine, the integrations write it for you:

  • glTF and GLB (Unlit Pixel Art in glTF, your own File > Export > glTF 2.0 included): linear filtering with mipmaps.

  • Godot: linear filtering with mipmaps.

  • Unity: trilinear filtering with mipmaps.

  • Unreal Engine: the Default filter, with mipmaps.

  • Generic Exporter: GLB and glTF as above. FBX writes the same two files as always: FBX has no word for filtering, so the PNG carries the padding and the tool you import into does the filtering.

  • A Closest texture exports exactly as before: nearest filtering, no mipmaps. Back on Closest, the next save puts the engine’s texture back to nearest.

Warning

N64 (3 Point) exports as Linear through glTF, the game engine integrations and the Generic Exporter. Blender’s own FBX and OBJ export find no texture while it’s on (the node group hides it from them): switch to Linear before a File > Export > FBX or OBJ.

Troubleshooting

  • Seams still show under Linear: the Setup note says when the islands are too close, click Lay Out Again. A faint step on a diagonal seam is expected.

  • Seams show from far away with a margin of 2 or 3: type 4 in Margin (px) and lay the UVs out again.

  • The Image Editor shows color around every island: that’s the padding, it goes away on Closest.

  • The FBX or OBJ came out with no texture: the texture is on N64 (3 Point), see the warning above.