About Spline Tools for Unity Splines
- Tools, Systems & Learning > Development Tools & Automation
- Tools, Systems & Learning > Level & World Building
Overview
Spline Tools adds a powerful Scene View toolbar overlay to Unity's built-in Spline system. Select any GameObject with a SplineContainer and the toolbar appears automatically, giving you instant access to a complete set of spline editing tools.
The toolbar is organized into three groups: Tool Buttons that each open a dedicated overlay panel, Toggle Buttons that stay active regardless of the selected tool, and Action Buttons for quick-access to common workflows.
Tool Buttons
* Flow - Click-drag on surfaces to paint splines freehand. Supports tension control, auto/manual point reduction, extend and replace modes, closed loops, and surface layer filtering. Mesh paint supports painting on a mesh without collider requirement, ideal for Spline Mas. A river scan mode traces downhill paths across Unity Terrain in real time while you drag spline knots. A lake scan mode can be used to create a spline of the terrain contour around a transform's position.
* Shape - Generate preset shapes including Line, Rectangle, Rounded Rectangle, Circle, Landscape (Perlin noise) and Race Track (procedural with self-intersection resolution). Pipette buttons pick dimensions from existing splines. Auto Apply for instant feedback.
* Create - Derive new splines from existing ones. Create parallel offset copies, spline segments as curbs using curvature criteria, generate bounding box splines around GameObjects, compute the 2D convex hull, create a spline path through a list of selected gameobjects. Optional Align to Surface snapping.
* Align - Snap knots to terrain or any surface via raycasting. Flatten along X, Y or Z using the selected knot's local axes. Configurable layer mask, ray distance, height offset and normal alignment.
* Smooth - Curvature-aware relaxation that targets sharp corners with configurable iterations, strength and angle threshold. Jitter mode adds controlled randomness to break up uniform paths.
* Scale - Expand or contract splines from their centroid. Uniform or per-axis scaling with an axis mask.
* Structure - Subdivide, unsubdivide, reduce knots (Ramer-Douglas-Peucker), distribute evenly, distribute at fixed intervals, reverse direction, unroll rotations, and mirror across any axis.
* Deform - The deform tool provides mechanisms to change the shape of a selected spline segment. Available are Banking, Looping, Wave, Twist, Hills, Spiral, Cobra Roll, Jump Ramp, Banked Turn, Noise
* Object - Copy and paste spline data between SplineContainers. Clear all splines from a container.
* Options - Configure the Gizmo visualiser (per-axis normals, spline length, segment distances) and Snap behaviour (ray distance, height offset, normal alignment) from a single panel.
Toggle Buttons
* Gizmo - Visualise spline normals, total length and segment distances in the Scene View. Each axis can be toggled independently with customizable colours. Stays active with any tool.
* Snap - Automatically snap knots to the closest surface while dragging them. Zero overhead when disabled.
Action Buttons
* Edit Mode - Enter spline edit mode instantly without navigating Unity's dropdown menus.
* Draw Spline - Activate Unity's spline creation tool with a single click.
* Knot Tool - Click on a curve to insert knots. Hold Ctrl to delete, Shift for free-placement.
* Select Tool - Brush-select knots by dragging. Shift-drag to add, Ctrl-drag to remove from the selection.
Additional Features
* Instant Edit Mode - Double-click gameobject to enter spline edit mode
* Pivot - Center the main handle at the spline centroid
* Popout - Show tool overlay content in editor window
* Pin - Show multiple tool panels as editor windows simultaneously for quick access
Preferences
Toolbar visibility modes, text label toggles, customisable gizmo colours, screen-relative or world-space normal length, and debug logging - all from Unity's Editor Preferences.
Spline Tools adds a powerful Scene View toolbar overlay to Unity's built-in Spline system. Select any GameObject with a SplineContainer and the toolbar appears automatically, giving you instant access to a complete set of spline editing tools.
The toolbar is organized into three groups: Tool Buttons that each open a dedicated overlay panel, Toggle Buttons that stay active regardless of the selected tool, and Action Buttons for quick-access to common workflows.
Tool Buttons
* Flow - Click-drag on surfaces to paint splines freehand. Supports tension control, auto/manual point reduction, extend and replace modes, closed loops, and surface layer filtering. Mesh paint supports painting on a mesh without collider requirement, ideal for Spline Mas. A river scan mode traces downhill paths across Unity Terrain in real time while you drag spline knots. A lake scan mode can be used to create a spline of the terrain contour around a transform's position.
* Shape - Generate preset shapes including Line, Rectangle, Rounded Rectangle, Circle, Landscape (Perlin noise) and Race Track (procedural with self-intersection resolution). Pipette buttons pick dimensions from existing splines. Auto Apply for instant feedback.
* Create - Derive new splines from existing ones. Create parallel offset copies, spline segments as curbs using curvature criteria, generate bounding box splines around GameObjects, compute the 2D convex hull, create a spline path through a list of selected gameobjects. Optional Align to Surface snapping.
* Align - Snap knots to terrain or any surface via raycasting. Flatten along X, Y or Z using the selected knot's local axes. Configurable layer mask, ray distance, height offset and normal alignment.
* Smooth - Curvature-aware relaxation that targets sharp corners with configurable iterations, strength and angle threshold. Jitter mode adds controlled randomness to break up uniform paths.
* Scale - Expand or contract splines from their centroid. Uniform or per-axis scaling with an axis mask.
* Structure - Subdivide, unsubdivide, reduce knots (Ramer-Douglas-Peucker), distribute evenly, distribute at fixed intervals, reverse direction, unroll rotations, and mirror across any axis.
* Deform - The deform tool provides mechanisms to change the shape of a selected spline segment. Available are Banking, Looping, Wave, Twist, Hills, Spiral, Cobra Roll, Jump Ramp, Banked Turn, Noise
* Object - Copy and paste spline data between SplineContainers. Clear all splines from a container.
* Options - Configure the Gizmo visualiser (per-axis normals, spline length, segment distances) and Snap behaviour (ray distance, height offset, normal alignment) from a single panel.
Toggle Buttons
* Gizmo - Visualise spline normals, total length and segment distances in the Scene View. Each axis can be toggled independently with customizable colours. Stays active with any tool.
* Snap - Automatically snap knots to the closest surface while dragging them. Zero overhead when disabled.
Action Buttons
* Edit Mode - Enter spline edit mode instantly without navigating Unity's dropdown menus.
* Draw Spline - Activate Unity's spline creation tool with a single click.
* Knot Tool - Click on a curve to insert knots. Hold Ctrl to delete, Shift for free-placement.
* Select Tool - Brush-select knots by dragging. Shift-drag to add, Ctrl-drag to remove from the selection.
Additional Features
* Instant Edit Mode - Double-click gameobject to enter spline edit mode
* Pivot - Center the main handle at the spline centroid
* Popout - Show tool overlay content in editor window
* Pin - Show multiple tool panels as editor windows simultaneously for quick access
Preferences
Toolbar visibility modes, text label toggles, customisable gizmo colours, screen-relative or world-space normal length, and debug logging - all from Unity's Editor Preferences.