Chapter 13: Node System and Procedural Workflow

Haiyue9/1/25About 3 min

Chapter 13: Node System and Procedural Workflow

Learning Objectives

Gain a deep understanding of the shader node system
Master the use of geometry nodes
Learn procedural modeling and distribution
Understand the creation of composite nodes
Master the creation and management of node groups

13.1 Node System Basics

Node Programming Concepts

Node: A computational unit that performs a specific function
Socket: The connection point between nodes
Node Tree: The overall structure of the node network
Data Flow: The transfer of data from input to output

Blender Node Types

Shader Nodes: Materials and lighting
Geometry Nodes: Procedural modeling
Compositor Nodes: Post-production compositing
Texture Nodes: Procedural textures

Node Editor Interface

Node Editor Operations:
- Shift+A: Add node
- Ctrl+G: Create node group
- Tab: Enter/exit node group
- Ctrl+J: Join selected nodes
- Alt+D: Duplicate node (shared data)

13.2 In-depth Shader Nodes

Core Shader Nodes

Principled BSDF:

Main Inputs:
- Base Color
- Metallic
- Roughness
- IOR: Index of Refraction
- Alpha: Transparency
- Normal: Normal map

Mix Node:

Types:
- Mix: Mix colors
- Add
- Multiply
- Overlay
- Color Burn

ColorRamp Node:

Uses:
- Color gradient mapping
- Mask control
- Value remapping
- Custom falloff

Procedural Texture Nodes

Noise Texture:

Parameters:
- Scale
- Detail
- Roughness
- Distortion

Wave Texture:

Types:
- Bands
- Rings
Profile: Waveform profile

Voronoi Texture:

Distance Metric:
- Euclidean
- Manhattan
- Chebychev
Feature: Feature type

Advanced Material Techniques

# Python Node Tree Operation Example
import bpy

def create_procedural_material(name):
    # Create a new material
    mat = bpy.data.materials.new(name=name)
    mat.use_nodes = True
    nodes = mat.node_tree.nodes
    links = mat.node_tree.links
    
    # Clear default nodes
    nodes.clear()
    
    # Add nodes
    output = nodes.new('ShaderNodeOutputMaterial')
    principled = nodes.new('ShaderNodeBsdfPrincipled')
    noise = nodes.new('ShaderNodeTexNoise')
    colorramp = nodes.new('ShaderNodeValToRGB')
    
    # Set positions
    output.location = (300, 0)
    principled.location = (0, 0)
    noise.location = (-400, 200)
    colorramp.location = (-200, 200)
    
    # Connect nodes
    links.new(noise.outputs['Fac'], colorramp.inputs['Fac'])
    links.new(colorramp.outputs['Color'], principled.inputs['Base Color'])
    links.new(principled.outputs['BSDF'], output.inputs['Surface'])
    
    return mat

13.3 Geometry Nodes System

Geometry Nodes Concepts

Geometry Data: Geometric information like meshes, curves, point clouds, etc.
Attribute System: Data stored on the geometry (position, color, normal, etc.)
Instancing: Efficiently copying and distributing geometry
Procedural Modeling: Generating geometric shapes through algorithms

Basic Geometry Nodes

Mesh Primitive:
```
- Cube
- Cylinder
- Ico Sphere
- Plane
```

Transform:

- Transform: Transform geometry
- Rotate
- Scale
- Translate

Instance:

- Instance on Points
- Rotate Instances
- Scale Instances

Attribute System

Attribute Types:
- Float
- Integer
- Vector: Position, velocity, etc.
- Color
- Boolean

Common Attributes:
- Position
- Normal
- Index
- ID

Distribution and Scattering

Distribute Points on Faces:

Inputs:
- Mesh: Target mesh
- Density
- Seed: Random seed

Outputs:
- Points: Distributed points
- Normal: Normal direction

Random Value:

Types:
- Float
- Integer
- Vector
- Boolean

Example: Procedural Forest

Forest Generation Workflow:
1. Terrain Mesh → Distribute Points on Faces
2. Random Value → Generate random scale and rotation
3. Collection Info → Get tree models
4. Instance on Points → Instance trees on points
5. Rotate/Scale Instances → Apply random transformations

13.4 Advanced Geometry Node Techniques

Geometry Operations

Mesh Operations:

- Join Geometry
- Separate Geometry
- Mesh to Points
- Points to Volume

Curve Operations:

- Curve to Mesh
- Curve Length
- Sample Curve
- Trim Curve

Field System

Field Concept:
- A value calculated at each point/element
- Can be a position-dependent function
- Supports mathematical operations and conditional judgments

Common Field Nodes:
- Position
- Index
- Random Value
- Noise Texture

Selection and Masking

Selection System:
- Compare: Comparison operations
- Boolean Math: Boolean operations
- Switch: Conditional switching

Application Example:
Select points with Z > 0 → Instance only in the upper half

13.5 Compositor Node System

Compositing Concepts

Pass: Different layers of rendered information
Multi-pass Rendering: Outputting color, depth, normal, etc., separately
Post-production Compositing: Combining multiple render passes

Basic Compositor Nodes

Input Nodes:

- Render Layers
- Image
- Movie Clip
- Mask

Output Nodes:

- Composite: Final output
- Viewer: Preview node
- File Output
- Split Viewer

Color Correction

Color Nodes:
- Bright/Contrast
- Hue Saturation Value
- Color Balance
- Curves
- Gamma

Filter Effects

Blur:

Types:
- Gaussian
- Bokeh
- Motion
- Bilateral

Filter:

- Sharpen
- Laplacian
- Sobel: Sobel edge detection
- Prewitt: Prewitt operator

13.6 Node Group Management

Creating Node Groups

Creation Steps:
1. Select the nodes to be grouped
2. Ctrl+G to create a node group
3. Set input/output interfaces
4. Name and save the node group

Node Group Interface

Group Input/Output:
- Add input parameters
- Set default values
- Name parameters
- Set data types

Node Group Library

Node Group Management:
- Save to .blend file
- Asset Browser integration
- Reuse across projects
- Version control

13.7 Practical Node Templates

Metal Material Node Group

Metal Material Composition:
- Base Color: Metal color
- Metallic: 1.0
- Roughness: Low value (0.1-0.3)
- Normal: Detail normal
- Add scratches and dirt effects

Fabric Material Node Group

Fabric Features:
- Subsurface: Subsurface scattering
- Roughness: High value (0.7-1.0)
- Sheen: Fabric sheen
- Normal: Fabric texture

Procedural Building

Building Generation Workflow:
1. Base geometry (cube)
2. Randomly divide into floors
3. Generate windows on the surface
4. Add detail decorations
5. Apply materials and textures

13.8 Performance Optimization

Node Tree Optimization

Optimization Strategies:
- Avoid unnecessary calculations
- Merge similar operations
- Use simplified versions for preview
- Cache complex calculation results

Geometry Node Optimization

Performance Considerations:
- Instancing is better than copying
- Point clouds are better than dense meshes
- LOD (Level of Detail) system
- View frustum culling

13.9 Practical Projects

Project 1: Procedural City

Key Techniques:
- Road network generation
- Building distribution
- Detail instancing
- Material variation

Project 2: Procedural Terrain

Implementation Steps:
1. Generate height map with Noise texture
2. Apply terrain with Displace modifier
3. Distribute vegetation based on height/slope
4. Add roads and buildings

Project 3: Procedural Material Library

Material Types:
- Wood texture series
- Metal surface series
- Stone texture series
- Fabric material series

Practical Exercises

Create a procedural grass system
Animate dynamic materials
Build a modular building system
Design a post-production compositing workflow
Develop a node tool library

Key Takeaways

The node system is one of Blender's core technologies
Shader nodes control the appearance of materials
Geometry nodes enable procedural modeling and distribution
Compositor nodes handle post-production compositing
Node groups improve work efficiency and code reuse
Attribute and field systems provide powerful data processing capabilities
Procedural workflows are suitable for large-scale scene creation

Next Chapter Preview

The next chapter will cover compositing and post-processing, delving into multi-pass rendering, color correction, and visual effects creation techniques.