Parametric Fading Pattern for Apple Watch | Webinar 8.0

Download Files: cademy.xyz/webinar8

In this session, we explored how to design an Apple Watch strap in Rhino 3D and build a complex fading surface pattern using Grasshopper. This workflow demonstrates how to transition from a flat design to a final curved wrist position, making it highly applicable for wearables, footwear, and flexible product design.

• High-quality surface modeling in Rhino using NURBS.
• Automating textures with the Patch command and Grasshopper.
• Parametric fading effects using Tween Curves.
• Dramatic lighting techniques in KeyShot using custom geometry.

Tools & Plugins

Software:

• Rhino 3D – For base strap modeling and spatial deformation.
• Grasshopper – For automating the fading pattern and point displacement.
• KeyShot – For cinematic product visualization and lighting.

Essential Techniques:

• Patch & Point Displacement – To create non-4-sided dimple textures.
• Flow Along Curve – To deform the final strap into a realistic wrist position.
• Spotlight Geometry – Creating custom laser-beam lighting effects.

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Step 1: Manual Patch Pattern in Rhino

Before automating, we establish the logic of the "Patch" technique on a single cell.

• Creating the Boundary: Start with a rectangular surface and trim a circular cutout to create a non-4-sided boundary.
• Defining Depth: Extract the centroid of the circle and move it along the Z-axis to set the desired depth or height of the dimple.
• Executing the Patch: Run the Patch command using both the circular boundary and the moved point as inputs.
• Precision Settings: Ensure the U & V span count is high enough (e.g., 20x20) to match the trimmed boundary within file tolerance (typically 0.001mm). If the patch fails to join the flat surface, increase the span count for more flexibility.

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Step 2: Linear Fading Logic

We apply the same logic to a more complex layout using curve interpolation.

• Tweening: Create two primary curves on a surface and use the TweenCurves command to generate an intermediate set.
• Subdividing: Use these tweened curves to split the underlying surface into multiple segments.
• Individual Patching: Extract the centroid for each segment, move them in the Z-axis, and patch them individually to create a repetitive fading effect.

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Step 3: Automating with Grasshopper

To handle dozens of cells at once, we transition the workflow into Grasshopper.

• The Patch Component: Use the Grasshopper Patch component with the boundary curves as the primary input.
• Data Management: Graft the list of curves and the list of points; this ensures the component loops correctly, assigning exactly one point to its corresponding boundary.
• Consolidation: Flatten the output and use the BRep Join component to merge the individual patches into a single polysurface.

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Step 4: Watch Strap Pattern 1 – Tween Fading

Now we apply the automated logic to the specific Apple Watch strap geometry.

• Surface Isolation: Isolate the top surface of the strap as the base for the pattern.
• Parametric Tweens: Generate two input curves and a range of numbers to control the number of tween steps dynamically.
• Normal Displacement: Instead of just the Z-axis, move the centroids in the Normal direction of the strap surface to ensure the depth remains consistent regardless of the strap's orientation.
• Result: Graft the inputs, execute the patch, and join the resulting BReps into a seamless textured surface.

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Step 5: Details & Deformation

Finalizing the strap involves transitioning from a flat design to a functional 3D form.

• Refining Details: Bake the Grasshopper result into Rhino and join it with the rest of the strap. Use curves to add functional details like buckle holes and strap loops.
• Flow Along Curve: Use the FlowAlongSrf or Flow command to map the flat, textured strap onto a target curve representing the wrist, bending the geometry into its final wearable position.

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Step 6: Watch Strap Pattern 2 – Polka Dot

For a different aesthetic, we use a grid-based distribution.

• Staggered Grid: Create a staggered (hexagonal) grid of points in Grasshopper and generate circles at each point.
• Projecting & Splitting: Project these circles onto the strap surface and use them to split "holes" into the geometry.
• Circular Patches: Use the projected circular edges and their centroids to generate the recessed "dimple" patch pattern.
• Final Wrap: Bake, join, and use Flow Along Curve to deform the polka dot pattern around the wrist.

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Step 7: KeyShot Rendering & Dramatic Lighting

We moved beyond standard HDRI lighting to create a more cinematic "reveal" style for the product.

13. Material Application: Applied realistic silicone and metal materials from the KeyShot library.
14. The "Laser" Light: Instead of a standard light, we created a sphere in KeyShot, converted it to a Spotlight, and squeezed it along one axis using the Gumball.
15. Atmospheric Effect: This created a laser-beam lighting effect, perfect for dramatic product shots.
16. Animation: Applied a subtle animation to the spotlight to create a "product reveal" sequence, moving the light across the textures to highlight the parametric depth.

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Step 8: 3D Printing the Strap

To bring the digital design into the physical world, the model must be converted into a high-fidelity mesh.

• Exporting STL: Export the final solid polysurface as an .stl file.
• Mesh Quality: In the mesh export tab, ensure a high-quality mesh by selecting a lower maximum edge length or a 1 to 2-degree angle setting to maintain the smoothness of the patches.
• Fabrication: For this project, we used a mix of flexible resin materials and printed the parts on an Elegoo Saturn to ensure the strap remains pliable and wearable.

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Conclusion

This workflow streamlines the creation of complex textures on flexible products. By combining the "Patch" logic in Rhino with the automation of Grasshopper, designers can iterate on patterns in seconds rather than hours. Whether you are designing wearables or industrial components, these parametric fading techniques offer a high level of control over aesthetics and function.

Thanks for reading ❤️