DocumentationSubstance 3DSubstance 3D Painter

Polygon Fill

Last update: October 21, 2026

The Polygon Fill tool fills polygons with material channel values or grayscale mask values. It can be used on paint layers, effects and masks to quickly fill regions of the mesh.

This tool is more of a painting tool than a selection tool: this is why after it has been used, it can only be erased via the eraser tool or by filling over it.

The tool can be accessed from the tool toolbar:

Settings

Below is the list of settings available with the Polygon Fill tool via the Properties window.

Selection mode

The selection mode controls how triangles and quads of the mesh geometry are selected.

Mode
Description
Rectangular marquee fill
Draw a rectangular selection by clicking and dragging. Fill mode defines what geometry is filled, while Hit-test defines which polygons are included.
Polygon loop fill
Fill a complete loop of quads with a single click. Dragging selects multiple loops.
Partial polygon loop fill
Fill a portion of a loop by clicking and dragging. The selection can extend along secondary loops to form a patch of polygons.

Fill mode

The fill mode, which can only be used with the Rectangular marquee fill mode, controls which parts of the geometry are selected.

Mode
Description
Triangle fill
Fill individual mesh triangles.
Polygon fill
Fill entire polygons. On a mesh triangulated before import, the result is the same as Triangle fill.
Mesh fill
Fill every polygon connected to the one clicked.
UV chunk fill
Fill polygons connected in UV space. The fill stops at UV borders.

Hit-test

The hit-test settings control how triangles and quads get selected by the Rectangular marquee fill mode.

Mode
Description
Intersection
(default) A polygon is filled if any part of its geometry is inside or intersects the selection area.
Contained center
A polygon is filled only if its center point lies inside the selection area.
Visible polygons only
If enabled, filling only affect polygons visible from the current camera view. Occluded and back-facing polygons are ignored. If disabled, polygons can be filled through the mesh.

Blending

These settings control how the fill result is mixed with the underlying pixels.

Parameter
Description
Blending Mode
Control how the fill is blended with existing pixel values. In Material mode, the blending mode applies to all channels enabled in the Material section.
Opacity
Control the opacity of the fill.
NOTE
The tool supports the same blending modes available in the layer stack. For more information, see the blending modes documentation page.

Material

The material section controls which channels can be enabled to be painted on by the tool.

Shortcuts

The Polygon fill tool can be used effectively with the help of specific keyboard shortcuts:

Shortcut
Description
Alt
With the Polygon loop fill and Partial polygon loop fill, this shortcut extends the selection on the other side of the initial click while dragging.
Shift
With the Partial polygon loop fill, this shortcut fills only the primary loop, ignoring the secondary loops. Example of toggling Shift:
Shift + A
This shortcut temporarily switches to Polygon loop fill from any other selection mode. If the shortcut is released before the mouse button, the selection continues until the mouse button is released.
A
If this shortcut is pressed while dragging, the current result is combined with the previous result. This works across blending modes and opacities:

Limitations

Some limitations apply to the tool:

  • Polygon loop fill and Partial polygon loop fill work on quads only, so triangles and n-gons can’t be filled with these modes.
  • Radial symmetry support is also limited and may be unreliable. To use symmetry prefer to use the mirror mode instead. See the symmetry documentation page for more information.
  • The tool fills geometry from the active Texture Set only. The wireframe is displayed for that Texture Set and updates when the active Texture Set changes.
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