Snap
Drop objects onto any surface, 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 clean 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 visible, mark them Live to re-measure, and export to CSV, JSON or an SVG blueprint.
Shape
Flatten and straighten, resize to an exact length, fit arcs, 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).New in v2.1.4 — Snap to Surface now shows a live preview: the object's own wireframe is drawn at the target position while you hover, with a marker on the contact point, and nothing moves until you click. A new Align Axis option lets you choose which local axis points out along the surface normal (+Z, −Z, +Y, −Y, +X, −X) — for anything that wasn't modelled Z-up. And exported SVG blueprints now carry the dimension values, printed beside each line.
Try GridSnap Free first
A free edition of the same add-on, so you can test the workflow before buying. It 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.
- 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, Saved & Live dimensions, CSV/JSON export, dimensioned SVG blueprints, the Correct suite (arcs, circles, corners), Shape Quality and parametric resize.
The Free edition installs the same way — Install from Disk — and can live alongside the Pro.
New in v2.1.3 — GridSnap Pro now follows your scene units everywhere: measurements, target radius and snap presets respect the scene's Length unit and Unit Scale (millimeter workflows read correctly out of the box). Arc, circle and corner corrections gain a Plane selector — Follow Shape (Best Fit) tracks tilted geometry automatically, or force a world axis. Plus Fit Circle to Radius, sharper shape analysis on tilted loops, and stability fixes.
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 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.03 · License
Activation.
A lightweight, privacy-friendly activation tied to your license key. Internet is required only once, during activation. After that, a small local license file unlocks the tools and no further connection is needed.
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 License removes the local 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. Marketplace editions without license keys unlock on install — you can skip this section.
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 supports Blender Undo and, where relevant, the F9 redo panel.
| Panel | What's inside |
|---|---|
| GridSnap Pro (main) | Header, status and Quick Actions. |
| Snap | Snap to Surface and Snap to Grid, plus an Align sub-panel (object alignment + transform). |
| Measure | Measure the selection, plus a Saved Dimensions sub-panel — persistent, Live re-measure and CSV/JSON export. |
| Shape | Vertex Cleanup, plus Correct (arcs & 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: m, cm, mm, in, ft.
- 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 → Snap to Grid box, Grid Step sets the real-world step used by the grid-snapping tools (default 10 cm). 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 step in scene units (range 0.0001–100). Space switches between World and Local.
06 · Feature reference
Every tool, by panel.
Snap · Snap to Surface
Drop the selected object(s) onto any surface in the scene. Click Snap to Surface and hover: the 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. 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 (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, so aligned objects sit flush instead of sinking in).
Snap · Snap to Grid
Set your Grid Step first, then quantize positions to it:
- Snap Selection — Object Mode rounds object origins; Edit Mode rounds selected vertices, onto the grid step.
- X / Y / Z — snap on a single axis only, leaving the other two unchanged.
- Snap Object Origin — rounds an object's origin to the grid.
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; 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 and arc.
- Connected vertices → polyline length.
- 2 objects → object-to-object distance.
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 Last Dimension for the clipboard.
Measure · Saved Dimensions
Turn a live measurement into a persistent, named dimension stored in the scene:
- Save Current / Update the selected dimension.
- 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.
- Select, Delete or Clear All; toggle each one visible individually.
- Export CSV / Export JSON (JSON 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 — corrects vertices into a clean circular arc. Smooth keeps the current angle; Target Angle 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 radius around its own center. The radius is read in the unit you choose — 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, 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 3–32, default 8) · Analysis 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, Line Width and optional Label Background.
Display & Setup · License & Help
License shows activation and status (marketplace editions unlock on install). Help offers quick in-app guidance and Open Documentation, which opens this page in your browser.
07 · In practice
Typical workflows.
Place a prop on a surface
- Select the prop(s).
- 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 quantize onto the grid.
- Use Parametric → Resize to Dimension to set an exact span.
- Measure Selection to confirm and Save the key ones.
- 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.
- Use a small custom Grid Step for detail work and a larger one 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 / "not activated" | 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. |
| Snap to Surface won't place | Make sure you're in Object Mode with object(s) selected, 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 (v2.1.4) to the local axis that should face out of the surface — e.g. +Y for props modelled facing forward. |
| 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. |
| 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 | Clear Local License 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. It installs as a Blender extension.
Is my data sent anywhere?
Only an anonymous Machine ID during one-time activation. No personal data and no scene data leave your computer. Marketplace editions don't contact the network at all.
Two computers?
Yes — each license includes 2 activations.
Is there a free version?
Yes — GridSnap Free 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, 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, parametric resize, cleanup, correct and shape tools work on vertex selections.
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 your Support Info from the License panel.
Contact
Support
support@contrast3d.com
Studio
contrast3d.com
Documentation
This page.
Precision, without the round-trip.
Drop onto surfaces, snap to exact increments, measure straight in the viewport, save 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.