Signed Distance Functions in Blender using Volume Cube Node

This repository provides a basic overview of Signed Distance Functions (SDFs) implemented using Blender's Volume Cube node (and Volume to Mesh node). SDFs represent objects mathematically by measuring the signed distance from any point in space to the closest point on a surface. This technique enables efficient visualization and manipulation of 3D objects.

Note: Majority of the functions work in Blender 3.6+, but the Mesh -> SDF node requires Blender 4.0. A fully 3.6-compatible version will be released in the future.

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Overview

Cover Example

Demonstrates smooth mixing between:

• A mesh converted to an SDF (Rock)
• A primitive SDF function (Sphere)

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Functions

1. Signed Distance Functions (SDFs)

Cylinder SDF

Represents a cylinder using the signed distance from the surface.

Sphere SDF

Defines a sphere as a signed distance function.

Box (Cube) SDF

Represents a cube using signed distance calculations.

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2. Mesh to Distance

Converts a mesh into an SDF.

• Functionality: Determines if a point is inside or outside the mesh.
• 4.0 Compatibility: Utilizes "samples" to evaluate multiple points for accurate results.
• 3.6 Compatibility: Lacks sample-based precision, leading to potential inaccuracies.

Limitations: Struggles with complex meshes; improvements are planned for future updates.

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3. Combine Operations

Allows combining or modifying SDFs using various mathematical operations:

• Intersection: Represents only the overlapping area by taking the maximum of the two SDFs.
• Difference: Subtracts one SDF from another.
• Union: Combines two SDFs into a single representation.
• Smooth Mix: Similar to Union, but blends the intersection smoothly.

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4. SDF to Density

Converts SDFs into a density function for processing within the Volume Cube Node.

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5. Bound Control

Defines the bounds for the Volume Cube Node to avoid infinite calculations.

• Combine Bounds: Expands bounds to include both SDFs when combining them.
• Expand Bounds: Manually increases the bounds for specific requirements.

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6. Density to Mesh

Processes density data into a mesh using the Volume Cube Node.

• Inputs density and bounds to create a mesh representation of the SDF.

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Notes on Blender Compatibility

• Blender 3.6+: Majority of the functions are supported.
• Blender 4.0+: Introduces sample-based evaluation in the Mesh to Distance function, enabling more accurate conversions.