Snap
Drop objects onto any surface with a live preview, and snap objects, origins and vertices to exact real-world increments.
Documentation · GridSnap Pro
GridSnap Pro.
Drop objects onto surfaces, snap to exact measurements, measure as you model, resize by the numbers, export dimensioned SVG blueprints, and correct rough geometry into clean shapes — all inside Blender, without the CAD round-trip.
01 · Overview
CAD-like precision, inside Blender.
A Blender add-on that brings exact precision into your normal modeling workflow — built for hard-surface artists, product-visualization artists, prop and mechanical/sci-fi modelers, and anyone who needs more precision without switching to CAD.
Measure
Measure distances, angles, radii, arcs and polylines, keep them as Saved Dimensions, mark them Live to re-measure, lock the ones that must not change, and export to CSV, JSON or an SVG blueprint.
Shape
Flatten and straighten, resize to an exact length, fit arcs, resize circles to a radius, fit corners to any angle, and push selections toward an ideal technical shape.
Requires Blender 4.2.0 or newer. Ships as a Blender extension (with
blender_manifest.toml). Version 2.1.6 was verified on Blender 4.5 and 5.2.New in v2.1.6 — a maintenance release focused on Saved Dimensions. A dimension now stores the exact geometry, object, type and vertex order that was measured, so changing the selection or the scene before you press Save Current no longer links it to the wrong thing. Three-point arcs and polylines keep their value and drawing when refreshed Live; object-to-object distances store both objects, so they can be Live too. A deleted reference is never re-linked to another object that reuses its name; instead the dimension keeps its last value and shows a warning (Reference missing or Topology changed). Labels and exports follow the units of the dimension's own scene. Update keeps the name, custom label, colour, visibility, Live flag and list position, and respects the new Lock dimension option. Snap Object Origin restores the cursor and the selection even if Blender raises an error. GridSnap Free goes to 1.0.1 with the shared fixes.
New in v2.1.5 — reliability fixes for snapping: Snap Object Origin rounds every selected origin independently (before, all of them landed on the first object's position); Align Rotation to World now really aligns objects that have a rotated parent; Contact = Base rests the bounding box on the surface even when the origin sits outside the geometry; Snap Selection to Grid processes every mesh in multi-object Edit Mode; and the Free and Pro editions can be installed side by side. It also introduced persistent object references, the stale-reference flag and Lock for Saved Dimensions, completed in 2.1.6.
Try GridSnap Free first
A free edition of the same add-on (currently 1.0.1), so you can test the workflow before buying. It installs its own GridSnap Free sidebar tab and includes:
- Measure — distances, angles, radii, arcs and polylines, read in the viewport in your scene units, with copy to clipboard.
- Snap to Grid — real-world grid steps and custom increments, on all axes or one, in World or Local space, plus Snap Object Origin.
- Vertex Cleanup — Flatten X/Y/Z and Straighten Vertices.
- Align Rotation to World and Apply Scale.
- The full viewport overlay system with all four styles.
What stays in Pro
Snap to Surface with live preview, Objects/Group to Active, Saved & Live dimensions with Lock, CSV/JSON export, dimensioned SVG blueprints, the Correct suite (arcs, circles, corners), Shape Quality and parametric resize. In the Free edition those panels stay visible as locked boxes with a Get GridSnap Pro button.
The Free edition installs the same way — Install from Disk — and can live alongside the Pro.
Earlier releases — v2.1.4 gave Snap to Surface its live wireframe preview (nothing moves until you click), the Align Axis option (+Z, −Z, +Y, −Y, +X, −X) and dimension values printed on exported SVG blueprints. v2.1.3 made the add-on follow your scene units everywhere (Length unit and Unit Scale), added the Plane selector for arc, circle and corner corrections — Follow Shape (Best Fit) or a forced world plane — and Fit Circle to Radius.
Index
Documentation sections.
A quick reference while you work in Blender. Each section covers one part of the add-on.
02 · First use
Installation.
Install the add-on
- Download the GridSnap Pro
.zipfrom your purchase. - In Blender, open Edit → Preferences → Add-ons.
- Click the ▾ menu (top-right) → Install from Disk… and select the
.zip. - Enable the checkbox next to GridSnap Pro if it isn't already.
- Open the 3D Viewport, press N, and select the GridSnap Pro tab.
Keep the zip
Install the .zip as you received it. It's a Blender extension containing blender_manifest.toml, the add-on code, the license file and the assets/ folder used for the panel logo.
Install the
.zip directly — don't unzip it first. Dragging the .zip onto the Blender window also works.Updating from an earlier version? Replace the extension from Blender's Preferences and then restart Blender, so the previous classes and handlers are fully unloaded.
03 · License
Activation.
This section only applies to the Gumroad edition, which ships with a license key. Activation is lightweight and privacy-friendly: internet is required only once, and after that a small local license file unlocks the tools with no further connection. The Superhive edition has no key at all — its License panel just reads Licensed via Superhive and every tool is unlocked on install.
Activate
- Open the GridSnap Pro sidebar → Display & Setup → License.
- Paste the license key you received after purchase.
- Click Activate License.
Key details
- Each license includes 2 activations (e.g. desktop + laptop).
- Bound to the machine via an anonymous Machine ID — no personal data is sent.
- Copy Machine ID / Copy Support Info shares diagnostics without exposing your key.
- Clear Local removes the local license file (it does not reset the store-side counter).
Changed hardware or used all activations? Email support@contrast3d.com with your Support Info and we'll reset your activation.
04 · UI map
Interface overview.
Everything lives in the 3D Viewport → Sidebar (N) → GridSnap Pro tab, organised into collapsible panels and sub-panels. Most tools work in Edit Mode on selected vertices; several also work in Object Mode on objects/origins. Every operator that changes geometry supports Blender Undo and, where relevant, the F9 redo panel.
| Panel | What's inside |
|---|---|
| GridSnap Pro (main) | Header, the two quick actions (Measure Selection, Snap to Surface) and the Overlay On/Off and Clear buttons. |
| Snap | Snap to Surface (Contact, Align to Surface, Align Axis) and Snap to Grid (Grid Step, Space, Snap Selection to Grid, X/Y/Z, Snap Object Origin), plus an Align sub-panel. |
| Measure | Units, Precision, Measure Selection, Copy and Save, with the readouts underneath, plus a Saved Dimensions sub-panel — persistent, Live re-measure, Lock and CSV/JSON export. |
| Shape | Vertex Cleanup, plus Correct (arcs, radius & corners) and Shape Quality sub-panels. |
| Parametric | Resize a selection to an exact target length. |
| Blueprint | Export visible Saved Dimensions as an SVG, from a top, front or side projection. |
| Display & Setup | License, Overlay Toggle & Style and HELP sub-panels. |
05 · Configuration
Settings.
Global preferences
Edit → Preferences → Add-ons → GridSnap Pro → Preferences:
- Default Units — display unit applied to scenes where you haven't chosen one yet. Default is Scene Units (Auto): labels follow the scene's Length unit and Unit Scale, matching Blender's own readouts. Fixed options: Meters, Centimeters, Millimeters, Inches, Feet.
- Default Precision — decimal places for labels (default 3, range 1–8).
- Default Overlay Color — technical overlay color (default high-visibility magenta).
- Support Email — contact shown inside the add-on.
- Debug Mode — extra diagnostics for support. Keep off for normal use.
Grid step
In the Snap panel, Grid Step sets the real-world step used by the grid-snapping tools (default 10 cm; presets from 1 mm to 1 m). Presets are real lengths — "1 mm" means one real millimeter in any unit setup, honoring the scene's Unit Scale.
Choose Custom to type your own Custom Step in scene units (range 0.0001–100, default 0.025). Space switches between World Space and Local Space.
06 · Feature reference
Every tool, by panel.
Snap · Snap to Surface
Drop the selected object(s) onto any surface in the scene. In Object Mode, click Snap to Surface and hover: the active object's own wireframe is drawn at the target position, with a marker on the contact point, so you see exactly where it will land (very dense meshes and non-mesh objects preview as a bounding box). Left-click to place it — nothing moves until you do. Right-click or Esc cancels. It works in any view — it casts a real ray, not the view axis, and the preview stays responsive even on dense meshes.
- Align to Surface — also rotates the object to sit flush with the face you click.
- Align Axis — with Align on, choose which local axis points out along the surface normal: +Z (up) (default), −Z, +Y, −Y, +X or −X. For objects that weren't modelled Z-up.
- Contact — choose what touches the surface: Origin (the object origin lands on the point) or Base (the object rests on the surface using the bottom of its bounding box — rotation-aware, and since 2.1.5 correct even when the origin sits outside the geometry).
Snap · Snap to Grid
Set your Grid Step first, then quantize positions to it:
- Snap Selection to Grid — Object Mode rounds object origins; Edit Mode rounds selected vertices (in every mesh you are editing at once), onto the grid step.
- X / Y / Z — snap on a single axis only, leaving the other two unchanged.
- Snap Object Origin — rounds each selected object's origin to the grid without moving its geometry (Object Mode). Your selection, active object and 3D cursor are restored afterwards.
Snap · Align
- Objects to Active — snaps selected object origins onto the active object's origin.
- Group to Active — moves the selected objects together onto the active, keeping their relative offset.
- Align Rotation to World — resets object rotation to world axes, also for objects with a rotated parent; location and scale preserved.
- Apply Scale — applies scale to 1,1,1 while keeping the visible size (keeps measurements accurate).
Measure · Measure Selection
Measure Selection reads the current selection into the overlay:
- 2 vertices → distance.
- 3 vertices → angle, radius, diameter and arc.
- Connected vertices → polyline or arc length.
- 2 objects (Object Mode) → distance between origins.
Readouts follow the Units dropdown in the Measure panel — Scene Units (Auto) by default, so a millimeter scene reads in millimeters — plus your Precision setting. For 3-vertex angles, the corner vertex is detected automatically; select side–corner–side. Use Copy for the clipboard and Save to keep the result as a Saved Dimension.
Measure · Saved Dimensions
Turn a measurement into a persistent, named dimension stored in the scene:
- Save Current — stores the last measurement with the exact object, mesh and vertices it was taken from. If you haven't measured yet, it measures the current selection first.
- Update — re-links the selected dimension to the current selection, keeping its name, custom label, colour, visibility, Live flag and position in the list.
- Live — flag a dimension as Live (the link icon) and it re-measures when the geometry changes. Use Refresh on demand, or turn on Auto-update to refresh continuously.
- Name, Label, Color and Lock dimension for the selected entry. A locked dimension is skipped by Update and by Live refresh. Automatic labels follow your current units; a label you typed yourself is kept as is.
- If a reference stops being valid the value is kept and a warning appears: Reference missing — value not updated (object or second object gone) or Topology changed — update this dimension (mesh replaced or vertex count changed). Select the geometry again and press Update.
- Toggle each one visible individually; Delete or Clear All.
- Export CSV / Export JSON — both refresh Live dimensions and labels first, in the current units (JSON also includes the overlay geometry).
Saved dimensions persist with the .blend and feed the SVG Blueprint export.
Blueprint · Export (SVG)
Export your visible Saved Dimensions as a clean, dimensioned vector blueprint, ready for documentation or client hand-off.
- Plane — choose the projection: Top (XY), Front (XZ) or Side (YZ).
- Export Blueprint (SVG) — writes an
.svgfrom the visible dimension lines and arcs, with each dimension's value printed beside its line, pushed clear of the drawing so it stays readable.
Only dimensions marked visible are exported — hide the ones you don't need first.
Parametric · Resize to Dimension
Resize geometry by the numbers instead of by eye.
- Target Length — type the exact size you want the selection's longest span to be.
- Resize to Dimension — scales the selected vertices so their longest span matches that length (Edit Mode, 2+ vertices; supports Undo).
Shape · Vertex Cleanup
- Flatten X / Y / Z — flattens selected vertices to their average position on one axis, for perfectly flat faces.
- Straighten Vertices — projects a row of selected vertices onto a straight line between its two ends.
Shape · Correct
- Plane — where the correction is rebuilt. Follow Shape (Best Fit) (default) fits the plane to the selected geometry itself, so tilted or rotated arcs stay true to their own plane; XY / XZ / YZ force a world plane.
- Fit Arc Smooth / Fit Arc to Target Angle — correct vertices into a clean circular arc. Smooth keeps the current angle; Target Angle (default 30°, 0.1–360°) fits to a set angle, with Even Spacing and Keep Endpoints options.
- Fit Circle to Radius — resizes a selected circle or arc to an exact Target Radius around its own center. The radius is read in the Unit you choose (Millimeters by default) — including Scene Units.
- Fit Corner to Angle — rebuilds a 3-point corner (side, corner, side) to a chosen Corner Angle (1–179°; 90° = a clean right angle), keeping the two endpoints fixed.
Shape · Shape Quality
Check how close a selection is to an ideal technical shape, then push it toward that shape.
- Check Shape Quality — reports a quality score (0–100), average and max deviation, symmetry and the fitted radius or major/minor axes, and draws an ideal-shape overlay.
- Select Problem Vertices — selects vertices outside the current tolerance.
- Correct Outline to Shape — projects vertices toward the ideal shape (destructive; supports Undo and F9).
Options: Expected Shape (Circle, Ellipse, Square, Rectangle, Diamond / Rhombus, Triangle, Hexagon, or Regular N-Gon with 3–32 sides, default 8) · Plane (Follow Shape (Best Fit) — tracks tilted loops, XY, XZ, YZ) · Tolerance % (default 5%, range 0.1–50) · Correction Strength (1.0 = exact, lower = softer, range 0.05–1.0).
Display & Setup · Overlay
- Viewport Overlay: On / Off — shows or hides the viewport overlay.
- Clear — clears the drawing without disabling overlay mode.
- Element toggles — Lines, Arc, Text, Points / Markers and Guides.
- Style — four technical presets: Pink Tech, Cyan Draft, White Blueprint and High Contrast; plus Custom Color, Text Size (8–32), Line Width (1–8) and optional Label Background with its Label Padding.
Display & Setup · License & HELP
License shows activation and status (the Superhive edition reads Licensed via Superhive and needs nothing). HELP offers Open Online Documentation, which opens this page in your browser, and the support address.
07 · In practice
Typical workflows.
Place a prop on a surface
- Select the prop(s) in Object Mode.
- Click Snap to Surface; move over the target surface and click to drop.
- Turn on Align to Surface to sit it flush on angled faces, and set Contact = Base so it rests on top.
Build to exact dimensions
- Set Grid Step to your step (e.g. 5 cm).
- Model roughly, then Snap Selection to Grid to quantize onto the grid.
- Use Parametric → Resize to Dimension to set an exact span.
- Measure Selection to confirm and Save Current the key ones; Lock the ones that must not change.
- Export CSV as a spec sheet, or an SVG blueprint for hand-off.
Clean a curved cut
- Select the vertex loop of the cut.
- Check Shape Quality as Circle to see the deviation.
- Select Problem Vertices, or Correct Outline to Shape / Fit Arc to fix it.
08 · Best practices
Tips that pay off.
- Work in whatever units your project needs — GridSnap Pro follows the scene's Length unit and Unit Scale for readouts, radii and snap steps. Millimeter workflows (Unit Scale 0.001) read correctly out of the box.
- Apply Scale before measuring or snapping objects with non-uniform scale — it avoids surprising results.
- Mark key dimensions Live so they track changes; turn on Auto-update while iterating and Lock the ones that are final.
- After operations that rebuild topology (a remesh, a boolean), re-measure and Update the dimensions on that mesh: a rebuild that keeps the same vertex count can't be detected automatically.
- Use a small Custom Step for detail work and a larger preset for blockouts.
- Keep the overlay on while measuring; toggle it off for clean screenshots.
- Hide the dimensions you don't want before an SVG blueprint export — only visible ones are written.
- The shape tools are destructive but Undo-friendly — check quality first, then correct.
09 · Fix common issues
Troubleshooting.
| Issue | Fix |
|---|---|
| Tools greyed out / "Tools locked" | Gumroad edition: open Display & Setup → License and activate your key (internet required once). |
| "Activation limit reached" | Both activations used. Email support with your Support Info for a reset. |
| Old version still showing after an update | Replace the extension in Preferences and restart Blender: the previous classes and handlers stay loaded until you do. |
| Snap to Surface won't place | Make sure you're in Object Mode with object(s) selected, run it from the 3D Viewport, and click on actual mesh geometry — the grid floor isn't a surface. |
| Snap to Surface flickers while hovering | Fixed in v2.1.4 — update the add-on. The object no longer moves during hover; you see a wireframe preview and it is placed on click. |
| Aligned object points the wrong way | Set Align Axis to the local axis that should face out of the surface — e.g. +Y for props modelled facing forward. |
| Contact = Base sinks in or floats | Fixed in v2.1.5 for objects whose origin sits outside their geometry. Also Apply Scale first on scaled objects. |
| Snap Object Origin puts every origin in the same place | Fixed in v2.1.5 — each selected origin is now rounded on its own, and your selection and cursor are restored. |
| Snap Selection only snaps one mesh in multi-object Edit Mode | Fixed in v2.1.5 — every mesh being edited is processed. |
| Align Rotation to World doesn't align a parented object | Fixed in v2.1.5 — the world matrix is rebuilt, so the object ends up on the world axes whatever its parent does. |
| Snapping moves objects too far/short | Check the Grid Step — presets are real-world lengths in any unit setup. On objects with unapplied scale, Apply Scale first. |
| Measurements show meters in a millimeter scene | Fixed in v2.1.3 — update the add-on. Units default to Scene Units (Auto); you can also pick a fixed unit in the Measure panel. |
| Saved dimension ended up linked to the wrong object | Fixed in v2.1.6 — Save Current keeps the exact object, mesh and vertex order that were measured, even if you changed the selection or the scene in between. |
| Live arc or polyline value jumps on Refresh | Fixed in v2.1.6 — three-point arcs and polylines keep their metric and drawing when refreshed. |
| Object-to-object distance can't go Live | Fixed in v2.1.6 — both objects are now stored. A distance saved with an older version never stored the second object: re-measure it and press Update. |
| "Reference missing — value not updated" | The object (or the second object) of that dimension was deleted or can't be resolved. The last value is kept. Select the geometry again and press Update. A deleted reference is never re-linked to a new object that reuses the name. |
| "Topology changed — update this dimension" | The mesh was replaced or its vertex count changed. Re-select the vertices and press Update. |
| Update does nothing / "Unlock this dimension before updating it" | The dimension is locked. Turn off Lock dimension, then Update. |
| Update lost my label, colour or list position | Fixed in v2.1.6 — Update now edits the dimension in place instead of deleting it and adding a new one. |
| Dimension reads in the wrong scale when another scene is active | Fixed in v2.1.6 — labels and exports use the units and Unit Scale of the scene the dimension belongs to. |
| CSV/JSON export keeps the old unit text | Fixed in v2.1.6 — exports refresh every label in the current units before writing. |
| Fit Arc bends out of my geometry's plane | Fixed in v2.1.3 — set Plane to Follow Shape (Best Fit) (default) or force an axis plane in the Correct panel. |
| Measurement looks wrong | Confirm the right vertex count (2 = distance, 3 = angle/arc) and Apply Scale on scaled objects. |
| Blueprint export is empty | Save at least one dimension and make sure it's set visible — only visible Saved Dimensions are exported. |
| Overlay not visible | Make sure Viewport Overlay is ON and the overlay color contrasts with the scene. |
| Moving to a new computer (Gumroad edition) | Clear Local on the old machine, then activate on the new one (uses one activation). |
Enable Debug Mode in Preferences only when asked by support — it adds extra diagnostic messages.
10 · FAQ
Frequently asked.
Does it replace CAD?
No. It brings practical precision tooling inside Blender — exact snapping, surface placement, measurement, parametric resize, SVG blueprints and shape correction — without the CAD round-trip.
Which Blender versions?
Blender 4.2.0 and newer, as a Blender extension. Version 2.1.6 was verified on Blender 4.5 and 5.2.
Is my data sent anywhere?
Only an anonymous Machine ID during the one-time activation of the Gumroad edition. No personal data and no scene data leave your computer. The Superhive editions (Pro and Free) don't contact the network at all.
Two computers?
Yes — each Gumroad license includes 2 activations.
Is there a free version?
Yes — GridSnap Free 1.0.1 includes Measure, Snap to Grid, Vertex Cleanup, the alignment tools and the full overlay, with no license key needed. It installs the same way and can live alongside the Pro. The Pro adds Snap to Surface, Objects/Group to Active, Saved & Live dimensions, exports and blueprints, the Correct suite, Shape Quality and parametric resize.
Object and Edit Mode?
Yes. Snap to Surface and the alignment tools work on objects in Object Mode; grid snapping works on origins (Object Mode) and vertices (Edit Mode); measurement works on vertex selections and on two objects; parametric resize, cleanup, correct and shape tools work on vertex selections.
What happens to dimensions saved with an older version?
They are migrated the first time they are resolved, as long as their object still exists under the name that was saved. An object renamed before that migration, or the second object of an old object-to-object distance, can't be reconstructed: re-measure it and press Update.
11 · Support & links
Get help.
Before you write in
- GridSnap Pro version & Blender version.
- Operating system.
- Screenshot of the issue.
- Full console traceback if there is an error.
- Exact steps to reproduce — and, on the Gumroad edition, your Support Info from the License panel.
Contact
Support
support@contrast3d.com
Studio
contrast3d.com
Precision, without the round-trip.
Drop onto surfaces, snap to exact increments, measure straight in the viewport, save, lock and re-measure Live dimensions, resize by the numbers, fit arcs and corners, verify shapes, and export SVG blueprints — all inside Blender. Check quality first, then correct.