Techniques For Non-Uniform Bevel Scaling On Blender Bezier Curves

Understanding Non-Uniform Scaling

Non-uniform scaling refers to scaling an object or parts of an object by different amounts along different axes. For Bezier curves in Blender, this means scaling the bevel or extrusion along the curve non-uniformly to create uneven geometry.

Use cases for non-uniform bevel scaling include:

• Creating tapered tubes or irregular organic shapes
• Simulating effects like twisting or deformation
• Adding variation to geometry extruded along a path

However, achieving consistent and predictable non-uniform scaling presents certain challenges, such as:

• Controlling the rate of scale change along the curve
• Avoiding unintended distortions and pinching
• Ensuring smooth transitions between areas with different scaling

The techniques covered in this article will help artists address these issues for clean, production-ready results.

Achieving Non-Uniform Scaling with Curve Tilts

The easiest way to create a non-uniformly scaled bevel on a Blender Bezier curve is to use the curve’s tilt property. Tilt provides direct control over how the bevel scales around each control point.

Using Tilts for Uneven Bevel Scaling

To demonstrate basic usage we can create a curved tapered tube mesh as follows:

1. Add a Bezier Circle curve and increase Resolution to add control points
2. With the curve selected also add a Bevel Object, in this case a simple plane
3. In edit mode, set the tilt value of each control point to scale the extruded bevel non-uniformly

As an example, setting tilts to 1 on the right side of the circle and 0 on the left blends between the original bevel dimensions on the right and a scaled down version on the left.

Step-by-Step Tilted Tube Tutorial

Follow these steps to create a tapered tube using tilt-based non-uniform bevel scaling:

1. Add a Bezier Circle curve with Resolution 32
2. In Object Data Properties add a Bevel Object as the extruded shape
3. Enter Edit Mode and select all control points on the right half of the circle
4. Set Tilt to 1 for this selection, leaving the other side with default tilt 0
5. Adjust bevel Start/End caps as needed to close off the mesh

This will make the tube taper in thickness from right to left. Further control variations can be achieved by setting intermediate tilt values per control point.

Advanced Control with Driver Functions

While tilt provides direct control, procedural effects can be achieved using driver functions to control the bevel factor.

Driver Function Basics

Driver functions provide a way to control properties programmatically based on variables and logic. To set up a driven bevel factor on a curve:

1. Add Driver to the Bevel Factor field
2. In Graph Editor, edit Driver variables and function to output scaled factor values

For example a sinusoidal driver function can create an oscillating thickness along the curve.

Tutorial for Driver-Controlled Bevels

Here is one approach to setting up a driver function for animated non-uniform bevel scaling:

1. Add input Float variable for the evaluation time
2. Use math nodes like Sine and Scale to control factor between 0-1 over time
3. Animate by keyframing the input time to see variations over the animation

More complex effects can be achieved with multiple inputs and combining math, vector, and logic nodes. This grants extensive control for procedurally scaling the beveled extrusion.

Troubleshooting Uneven and Inconsistent Results

When attempting controlled non-uniform scaling, issues like uneven geometry, pinching, and inconsistent output are common. Here are some potential solutions:

Identifying Bevel Geometry Issues

Look for:

• Twisting or deformation along the affected curve span
• Pinching visible where bevel dimensions transition
• Flat or irregular areas interrupting the bevel shape

These indicate problems with the curve calculation, tilt values, or bevel settings.

Techniques for Correcting Result Distortions

Try these fixes:

• Increase curve resolution for smoother handling of non-uniform scaling
• Adjust control point tilts gradually to prevent extreme transitions
• Double check bevel object scale, and Start/End caps settings
• Consider adding supporting edge loops or geometry

Taking time to refine and smooth out variations can improve stability significantly.

Example Assets for Experimentation

Having quality sample Blend files enables quickly iterating on non-uniform bevel techniques without needing to rebuild curves and test assets from scratch.

Files for Practicing Scaling Techniques

Basic curves set up to experiment with include:

• Tapered and twisted tubes
• Curved pipes with driver-controlled thickness
• Organically bulging ropes and hoses
• Custom extruded shapes like blades and arrows

These samples have different curve settings, bevel objects, and tilts or drivers ready to evaluate and extend.

Tips for Modifying and Adapting Assets

When working with the provided files note that:

• Making extreme changes to tilt may distort geometry
• Support loops around large bevels prevents deformation
• The bevel object may need scaling adjustments to smooth transitions

Take an incremental approach when altering existing non-uniform scaling setups for optimal quality.

Expanding On Non-Uniform Effects

Non-uniform scaling serves as a foundation for taking bevel distortion even further to create more organic and dramatic results.

Possibilities for Advanced Techniques

To build on the methods covered, explore options like:

• Animating curves and tilts for morphing organic effects
• Combining non-uniform scaling with Lattice and Mesh deformers
• Rigging mesh parts and control curves for easier animation
• Converting curves to mesh for finer adjustments

Blending techniques expands the range of possible deformations greatly.

Integration with Modeling Tools

These and other Blender features complement non-uniform curve extrusion:

• Sculpting for detailed organic deformations
• Proportional editing to smoothly adjust areas
• Shape keys for animating morph targets
• Mesh deform cage for precise control

Used creatively in combination, all modeling, curve, and animation tools can help enhance non-uniform bevel effects.