Chapter 5: Material System and Shaders

Haiyue1/5/24About 6 min

Chapter 5: Material System and Shaders

Learning Objectives

Understand the material and shader node system
Master PBR (Physically Based Rendering) material creation
Learn texture mapping and UV unwrapping
Master procedural material creation
Understand lighting models and material interaction

Detailed Knowledge Points

5.1 Material System Basics

5.1.1 Material and Shader Concepts

Material = A collection of properties describing the surface of an object
Shader = An algorithm that calculates the interaction of light with a surface

Material properties include:

Color
Reflectance
Roughness
Metallic
Transparency
Emission

5.1.2 Blender Material Workflow

# Material creation process
1. Select the object
2. Switch to the Shading workspace
3. Click "New" to create a material
4. Edit the material using the node editor
5. View the effect in the 3D viewport (Material Preview/Rendered)

5.2 Shader Node System

5.2.1 Node Editor Interface

Node Editor Components:

┌─────────────────────────────────────┐
│ Toolbar    Header Bar    Menu Bar        │
├─────────────────────────────────────┤
│                                     │
│        Node Network Editing Area            │
│                                     │
├─────────────────────────────────────┤
│ Node Library               Properties Panel      │
└─────────────────────────────────────┘

Basic Node Operations:

# Add a node
Shift + A  # Add node menu

# Connect nodes
Left-click drag  # Connect output to input socket

# Node operations
X / Delete  # Delete node
Ctrl + C/V  # Copy/paste node
Tab        # Edit node group
Ctrl + J   # Join nodes

5.2.2 Core Shader Nodes

Principled BSDF:
This is the most important shader node, based on Disney's PBR standard:

Principled BSDF parameters:
├── Base Color
├── Metallic: (0=insulator, 1=metal)
├── Roughness: (0=mirror, 1=completely rough)
├── IOR: Index of Refraction
├── Alpha: Transparency
├── Subsurface: Subsurface scattering
├── Specular: Specular reflection intensity
├── Transmission: Transmission
├── Emission: Emission
└── Normal: Normal map input

Other Important Shaders:

Shader Type	Use	Features
Diffuse BSDF	Diffuse reflection	Ideal diffuse surface
Glossy BSDF	Specular reflection	Metal and smooth surfaces
Glass BSDF	Glass	Transparent refractive material
Emission	Emission	Self-illuminating material
Mix Shader	Mix shaders	Combine multiple materials

5.3 PBR Material Creation

5.3.1 PBR Workflow

Physically Based Rendering (PBR) Principles:

Energy conservation: Reflection + absorption + transmission = 1
Fresnel effect: Viewing angle affects reflection intensity
Microfacet theory: Surface roughness affects reflection

PBR Map Types:

PBR standard map set:
├── Albedo/Diffuse: Base color map
├── Normal: Normal map (surface details)
├── Roughness: Roughness map
├── Metallic: Metallic map
├── AO: Ambient Occlusion map
├── Height/Displacement: Height map
└── Emission: Emission map

5.3.2 Common Material Type Creation

Metal Material:

# Gold material settings
Principled BSDF:
├── Base Color: RGB(1.0, 0.766, 0.336)
├── Metallic: 1.0
├── Roughness: 0.1-0.3
├── IOR: 0.47 (refractive index of gold)
└── Specular: 1.0

# Stainless steel material
├── Base Color: RGB(0.672, 0.672, 0.672)
├── Metallic: 1.0
├── Roughness: 0.2-0.5
└── IOR: 2.9

Plastic Material:

# Smooth plastic
Principled BSDF:
├── Base Color: Any color
├── Metallic: 0.0
├── Roughness: 0.1-0.3
├── IOR: 1.45 (typical plastic refractive index)
└── Specular: 0.5

Glass Material:

# Transparent glass
Principled BSDF:
├── Base Color: RGB(1.0, 1.0, 1.0)
├── Metallic: 0.0
├── Roughness: 0.0
├── IOR: 1.52 (glass refractive index)
├── Transmission: 1.0
└── Alpha: 0.0 (fully transparent)

5.4 Texture Mapping Basics

5.4.1 UV Coordinate System

UV Coordinate Concept:

U-axis: Horizontal direction (0-1)
V-axis: Vertical direction (0-1)

3D mesh → UV unwrap → 2D texture space

5.4.2 Texture Coordinate Node

Texture Coordinate Node Outputs:

Generated: Automatically generated coordinates
UV: UV map coordinates
Object: Object coordinates
Camera: Camera coordinates
Window: Window coordinates
Normal: Normal coordinates
Reflection: Reflection coordinates

Mapping Node:
Used to transform texture coordinates

Mapping parameters:
├── Location: Position offset
├── Rotation: Rotation angle
├── Scale: Scale factor
└── Vector Type:
   ├── Texture
   ├── Point
   ├── Vector
   └── Normal

5.5 Procedural Material Creation

5.5.1 Noise Texture Node

Noise Texture:

Parameter settings:
├── Scale: Noise scale
├── Detail: Detail levels
├── Roughness: Roughness
├── Lacunarity: Lacunarity
├── Distortion: Distortion
└── Dimension: Dimension

Outputs:
├── Fac: Grayscale value (0-1)
└── Color: Color noise

Other Procedural Textures:

Texture Type	Use	Features
Wave Texture	Wave texture	Regular wave patterns
Voronoi Texture	Voronoi polygons	Cell-like patterns
Musgrave Texture	Fractal noise	Complex terrain textures
Gradient Texture	Gradient texture	Linear/radial gradients
Magic Texture	Magic texture	Psychedelic patterns
Brick Texture	Brick texture	Brick wall patterns

5.5.2 ColorRamp Node

ColorRamp is used to remap color values:

# ColorRamp application
Noise Texture → ColorRamp → Material parameter

Common techniques:
1. Control contrast (adjust color stop positions)
2. Create masks (black and white output)
3. Color layering (multiple color stops)
4. Smooth transitions (interpolation type)

5.6 Advanced Shading Techniques

5.6.1 Layered Materials

Use Mix Shader to blend multiple materials:

# Layered material example: Rusted metal
Metal layer (Principled BSDF - metal parameters)
     ↓
Mix Shader
     ↓
Rust layer (Principled BSDF - insulator parameters)

# Mix factor controlled by texture
Noise Texture → ColorRamp → Mix Shader.Fac

5.6.2 Subsurface Scattering

Simulates light scattering inside a material:

# Skin material
Principled BSDF:
├── Subsurface: 0.1-0.5
├── Subsurface Radius: RGB(1.0, 0.2, 0.1)
├── Subsurface Color: Skin base color
└── Base Color: Skin surface color

# Candle material
├── Subsurface: 0.3
├── Subsurface Color: Warm yellow
└── Transmission: 0.9

5.6.3 Displacement Map

Use height information to change the geometry shape:

# Displacement setup process
1. Connect Displacement in the material output node
2. Image Texture → ColorRamp → Displacement
3. Add a Subdivision Surface modifier
4. Enable Adaptive Subdivision (experimental feature)

# Displacement strength control
Math node to adjust displacement strength:
Height Map → Math(Multiply) → Displacement

5.7 Material Optimization and Management

5.7.1 Material Library Management

# Save and reuse materials
1. After creating a material, click the "Fake User" button
2. File → Append/Link to import materials from other files
3. Use the Asset Browser to manage material libraries
4. Create material node groups for easy reuse

# Create node groups
1. Select the nodes to be grouped
2. Ctrl + G to create a node group
3. Tab to edit the node group
4. Add input/output nodes to define the interface

5.7.2 Render Optimization

# Material render optimization techniques
1. Use appropriate texture resolutions
   - Distant objects: 512x512 or lower
   - Close-up objects: 2048x2048 or higher

2. Avoid overly complex node networks
   - Simplify with node groups
   - Delete unused nodes

3. Enable GPU render acceleration
   - Cycles: CUDA/OpenCL/OptiX
   - Set sample counts reasonably

5.8 Practical Exercises

Exercise 1: Wood Material Creation

Exercise Goal

Master procedural material creation and node combination techniques

# Procedural wood material creation
# Step 1: Create base wood grain
1. Add a Wave Texture node
2. Type: Bands, Profile: Saw
3. Scale: 20, Distortion: 2

# Step 2: Add wood grain variation
4. Add a Noise Texture
5. Scale: 5, Detail: 10
6. Connect to the Wave Texture's Distortion

# Step 3: Color adjustment
7. Wave Texture → ColorRamp
8. Set two color stops: light wood and dark wood
9. ColorRamp → Principled BSDF Base Color

# Step 4: Surface details
10. Duplicate the noise texture for roughness
11. Adjust strength: Math node × 0.3
12. Connect to Roughness input

# Step 5: Normal details
13. Add another Noise Texture (smaller scale)
14. Connect to a Normal Map node
15. Normal Map → Principled BSDF Normal

Exercise 2: Car Paint Material

# Car metallic paint material
# Step 1: Base car paint
1. Principled BSDF settings:
   - Base Color: Choose car color
   - Metallic: 0.0 (car paint is an insulator)
   - Roughness: 0.1 (smooth)
   - IOR: 1.5

# Step 2: Metallic flake effect
2. Add a Noise Texture (Scale: 1000)
3. ColorRamp to adjust contrast
4. Math node to adjust strength × 0.1
5. Connect to Metallic input

# Step 3: Clear coat effect
6. Add a Mix Shader
7. First input: The car paint material above
8. Second input: Glossy BSDF (Roughness: 0.05)
9. Factor: 0.1 (10% clear coat)

# Step 4: Enhance environment reflection
10. Add a Layer Weight node
11. Fresnel output → Mix Shader Factor
12. Enhance edge reflection effect

Exercise 3: Complex Fabric Material

Important Notes

Fabric materials require proper UV unwrapping
Pay attention to the anisotropic reflection of fibers
Use subsurface scattering to simulate light transmission

# Sweater fabric material
# Step 1: Base fabric color
1. Choose a suitable fabric base color
2. Principled BSDF Base Color

# Step 2: Fabric texture
3. Use a Brick Texture to simulate woven texture
4. Scale: 50, Mortar: 0.02
5. Set different light/dark shades for Color1/Color2

# Step 3: Surface fuzz effect
6. Add a Hair BSDF
7. Mix Shader to blend Principled and Hair
8. Factor controlled by texture (around 0.3)

# Step 4: Subsurface scattering
9. Enable Subsurface: 0.1
10. Subsurface Color: Slightly warmer than Base Color

# Step 5: Normal details
11. Use a Noise Texture to create subtle bumps
12. Normal Map strength: 0.5
13. Simulate fiber surface texture

5.9 Node Shortcuts and Tips

5.9.1 Node Editing Shortcuts

Operation	Shortcut	Description
Add Node	Shift + A	Open add menu
Delete Node	X / Delete	Delete selected node
Duplicate Node	Shift + D	Duplicate and move
Cut Links	Ctrl + Right-click drag	Cut node connections
Preview Node	Ctrl + Shift + Left-click	Preview node output
Mute Node	M	Disable node
Hide Node	H	Hide selected node
Node Group	Ctrl + G	Create node group
Enter Node Group	Tab	Edit node group
Search Node	Ctrl + A	Smart add node

5.9.2 Efficient Node Editing Tips

# Quick node connection
1. Node Wrangler add-on (built-in)
   - Ctrl + Shift + T: Add texture setup nodes
   - Ctrl + T: Add Mapping + Texture Coordinate

# Align nodes
2. After selecting multiple nodes:
   - Shift + = : Align nodes

# Quick preview
3. Ctrl + Shift + Left-click: Temporarily output to material output
   Convenient for quickly viewing intermediate node effects

# Search and add nodes
4. Shift + A then type the node name
   e.g., "noise" to quickly find Noise Texture

5.10 Render Engine Differences

5.10.1 Cycles vs Eevee Material Differences

Cycles (Offline Renderer):

Full support for all node types
Physically accurate ray tracing
Supports complex volume rendering
High render quality but slower speed

Eevee (Real-time Renderer):

Limited support for some nodes
Real-time rendering based on rasterization
Requires pre-processing (baking) for some effects
Fast speed but compromised quality

Material Compatibility:

Feature	Cycles	Eevee	Notes
Principled BSDF	✓	✓	Fully supported
Volume Scattering	✓	Partial	Eevee requires enabling volume
Displacement Map	✓	✗	Not supported in Eevee
Subsurface Scattering	✓	✓	Both support
IOR Refraction	✓	Approximate	Eevee uses screen space

Learning Suggestions

Start with the Basics: First master the various parameters of the Principled BSDF
Observe Reality: Observe the light and shadow changes of real materials
Be Experimental: Try different node combinations
Reference Learning: Study the material creation of excellent works
Stay Organized: Use Frame and Reroute nodes to organize complex networks

By completing this chapter, you should be able to:

Use the shader node system proficiently
Create various types of PBR materials
Understand procedural material creation methods
Master material optimization and management techniques

Material creation is an important part of 3D art, requiring a combination of technical knowledge and artistic sense.