Chapter 8: Animation Basics and Keyframes

Haiyue1/1/24About 7 min

Chapter 8: Animation Basics and Keyframes

Learning Objectives

Understand the basic principles and concepts of 3D animation
Master Blender's animation tools and interface
Learn to create and edit keyframe animations
Become proficient in using the timeline and animation editors
Master easing and animation curve adjustment
Learn to create various basic animation effects

Chapter Focus

Animation is the art of bringing 3D models to life. This chapter will guide you into the world of animation, mastering skills from basic keyframing to complex animation production.

8.1 Basic Animation Theory

8.1.1 Basic Animation Principles

The 12 Principles of Animation by Disney

Classic principles of traditional animation that are still important guides for 3D animation:

Squash and Stretch: Expresses the softness and weight of an object
Anticipation: Preparatory action before the main action
Staging: Clearly expressing ideas and emotions
Straight Ahead Action and Pose to Pose: Two methods of animation production
Follow Through and Overlapping Action: Time difference between different parts
Slow In and Slow Out: Natural acceleration and deceleration
Arcs: Natural motion paths
Secondary Action: Details that support the main action
Timing: Rhythm and speed control
Exaggeration: Enhancing expressiveness
Solid Drawing: Foundational drawing skills
Appeal: The quality that attracts the audience

8.1.2 Frame Rate and Time

# Common Frame Rate Standards
frame_rates = {
    'film': 24,           # Film standard
    'pal_tv': 25,         # PAL TV standard
    'ntsc_tv': 29.97,     # NTSC TV standard
    'web_video': 30,      # Web video
    'gaming': 60,         # Gaming standard
    'vr': 90,            # VR content
    'animation_2d': 12    # Common for 2D animation
}

8.1.3 Keyframe System

# Keyframe Types
keyframe_types = {
    'KEYFRAME': 'Normal Keyframe',
    'EXTREME': 'Extreme Keyframe',
    'JITTER': 'Jitter Keyframe', 
    'MOVING_HOLD': 'Moving Hold',
    'BREAKDOWN': 'Breakdown Keyframe'
}

8.2 Blender Animation Workspace

8.2.1 Animation Workspace Layout

Animation Workspace Components

3D Viewport: View animation effects
Timeline: Manage keyframes
Dope Sheet: Detailed frame editing
Graph Editor: Animation curve editing
Properties Panel: Animation property settings

8.2.3 Animation Playback Controls

Shortcut	Function	Description
`Spacebar`	Play/Pause	Toggle playback state
`←` `→`	Previous/Next Frame	Single frame browsing
`↑` `↓`	Fast Forward/Rewind	10-frame jump
`Shift + ←`	Jump to Previous Keyframe	Quick navigation
`Shift + →`	Jump to Next Keyframe	Quick navigation
`Alt + A`	Play Animation	Fullscreen playback

8.3 Keyframe Animation Production

8.3.1 Inserting Keyframes

Keyframe Insertion Methods

Keyframes are the foundation of animation, recording the state of an object at a specific time.

# Shortcut for Inserting Keyframes
keyframe_shortcuts = {
    'I': 'Insert Keyframe Menu',
    'Shift + I': 'Delete Keyframe Menu',
    'Alt + I': 'Clear Keyframe Menu'
}

# Animatable Properties
animatable_properties = [
    'Location',      # Position
    'Rotation',      # Rotation
    'Scale',         # Scale
    'LocRot',        # Location + Rotation
    'LocScale',      # Location + Scale
    'RotScale',      # Rotation + Scale
    'LocRotScale',   # All transforms
    'Custom'         # Custom properties
]

8.3.2 Keyframe Type Management

# Keyframe Color Coding
keyframe_colors = {
    'KEYFRAME': 'Yellow - Normal Keyframe',
    'EXTREME': 'Red - Extreme Keyframe',
    'JITTER': 'Green - Jitter Keyframe',
    'MOVING_HOLD': 'Dark Yellow - Moving Hold',
    'BREAKDOWN': 'Cyan - Breakdown Keyframe'
}

8.3.3 Auto Keyframe Settings

# Auto Keyframe Options
auto_keyframe_settings = {
    'auto_keying': True,           # Enable auto keying
    'auto_keying_mode': 'ADD_REPLACE_KEYS',  # Mode
    'use_keyframe_insert_needed': True,      # Insert only when needed
    'use_visual_keying': False,     # Visual keying
    'use_insertkey_xyz_to_rgb': False  # XYZ to RGB
}

8.4 Animation Curve Editing

8.4.1 Introduction to the Graph Editor

The Graph Editor displays the change of animation properties over time as curves, and is the core tool for precise animation control.

# F-Curve (Function Curve) Properties
fcurve_properties = {
    'data_path': 'location',    # Data path
    'array_index': 0,           # Array index (X=0, Y=1, Z=2)
    'keyframe_points': [],      # Collection of keyframe points
    'interpolation': 'BEZIER',  # Interpolation type
    'extrapolation': 'CONSTANT' # Extrapolation type
}

8.4.2 Interpolation Modes Explained

Interpolation Type	Characteristics	Application	Visual Effect
Constant	Constant, no transition	On/off animation	Stepped
Linear	Linear interpolation	Constant speed motion	Straight line
Bezier	Bezier curve	Natural motion	Smooth curve
Sine	Sine interpolation	Periodic motion	Sine wave
Quad	Quadratic interpolation	Accelerated motion	Parabola
Cubic	Cubic interpolation	Smooth transition	S-shaped curve

8.4.3 Easing Settings

Importance of Easing

Easing makes animations more natural and conforms to the laws of motion in the physical world.

# Easing Types
easing_types = {
    'ease_in': 'Ease In - Slow start',
    'ease_out': 'Ease Out - Slow end', 
    'ease_in_out': 'Ease In/Out - Slow start and end',
    'back': 'Back - Overshoots and returns',
    'bounce': 'Bounce - Multiple bounces',
    'elastic': 'Elastic - Elastic oscillation',
    'expo': 'Exponential - Exponential change',
    'circ': 'Circular - Circular arc trajectory',
    'quart': 'Quartic - Strong acceleration/deceleration'
}

8.4.4 Curve Modifiers

# F-Curve Modifiers
fcurve_modifiers = {
    'GENERATOR': {
        'type': 'Generator',
        'use': 'Generate animation with a mathematical function',
        'example': 'y = a*x + b'
    },
    'NOISE': {
        'type': 'Noise',
        'use': 'Add random variation',
        'params': ['scale', 'strength', 'phase', 'offset']
    },
    'CYCLES': {
        'type': 'Cycles',
        'use': 'Repeat animation segment',
        'modes': ['repeat', 'repeat_with_offset', 'reflected']
    },
    'LIMITS': {
        'type': 'Limits',
        'use': 'Limit the value range',
        'params': ['min_x', 'max_x', 'min_y', 'max_y']
    }
}

8.5 Advanced Animation Techniques

8.5.1 Motion Path Animation

# Follow Path Settings
follow_path_settings = {
    'target': 'curve_object',     # Target curve
    'use_curve_follow': True,     # Follow curve direction
    'use_fixed_location': False,  # Fixed location
    'forward_axis': 'FORWARD_Y',  # Forward axis
    'up_axis': 'UP_Z',           # Up axis
    'offset_factor': 0.0         # Offset factor
}

Creating Motion Path Animation Steps

Create a Bezier curve as the path
Select the object to be animated
Add a "Follow Path" constraint
Set keyframes for the curve's "Evaluation Time"

8.5.2 Shape Key Animation

# Shape Keys
shape_keys = {
    'basis': 'Basis',           # Base shape
    'key_1': 'Smile',           # Smile
    'key_2': 'Frown',           # Frown
    'key_3': 'Surprise',        # Surprise
    'value_range': (0.0, 1.0),  # Value range
    'relative': True            # Relative deformation
}

8.5.3 Driver Animation

Driver Concept

Drivers allow the change of one property to drive the change of another, creating procedural animation effects.

# Driver Setup Example
driver_setup = {
    'type': 'SCRIPTED',          # Scripted driver
    'expression': 'var * 2.0',   # Expression
    'variables': [
        {
            'name': 'var',
            'type': 'TRANSFORMS',
            'target': 'controller_object',
            'transform_type': 'LOC_X'
        }
    ]
}

8.6 Dope Sheet Explained

8.6.1 Dope Sheet Interface

The Dope Sheet provides a familiar workflow from traditional animation, displaying keyframes in a timeline format.

# Dope Sheet Modes
dopesheet_modes = {
    'DOPESHEET': 'Main Dope Sheet',
    'ACTION': 'Action Editor',
    'SHAPEKEY': 'Shape Key Editor',
    'GPENCIL': 'Grease Pencil Animation Editor',
    'MASK': 'Mask Editor',
    'CACHEFILE': 'Cache File Editor'
}

8.6.2 Keyframe Operations

Operation	Shortcut	Function Description
Select	Left-click	Select keyframe
Multi-select	Shift + Left-click	Add to selection
Box Select	B	Box selection
Move	G	Move keyframe
Duplicate	Shift + D	Duplicate keyframe
Delete	X or Delete	Delete keyframe
Scale	S	Time scaling

8.6.3 Batch Editing Techniques

# Batch Keyframe Operations
batch_keyframe_ops = {
    'select_all': 'A',           # Select all
    'select_none': 'Alt + A',    # Deselect all
    'select_inverse': 'Ctrl + I', # Invert selection
    'select_linked': 'L',        # Select linked
    'duplicate': 'Shift + D',    # Duplicate
    'mirror': 'Ctrl + M',        # Mirror
    'snap': 'Shift + S'          # Snap
}

8.7 Animation Layers and Blending

8.7.1 Introduction to the NLA Editor

The Non-Linear Animation (NLA) editor allows you to combine and blend multiple animation sequences.

# NLA Track Settings
nla_track_settings = {
    'name': 'Walk_Cycle',        # Track name
    'active': True,              # Active state
    'lock': False,               # Lock state
    'mute': False,               # Mute state
    'solo': False,               # Solo state
    'influence': 1.0             # Influence strength
}

8.7.2 Animation Strip Operations

# NLA Strip Properties
nla_strip_properties = {
    'action': 'walk_action',     # Associated action
    'frame_start': 1,            # Start frame
    'frame_end': 30,             # End frame
    'blend_type': 'REPLACE',     # Blend type
    'influence': 1.0,            # Influence factor
    'use_auto_blend': True,      # Auto blend
    'blend_in': 5,               # Fade-in frames
    'blend_out': 5               # Fade-out frames
}

8.7.3 Animation Blending Modes

Blend Mode	Effect Description	Application
Replace	Replaces the original animation	Main action
Add	Adds to the animation	Additive effects
Subtract	Subtracts from the animation	Reverse action
Multiply	Multiplies the animation	Scaling effects

8.8 Animation Constraint System

8.8.1 Common Animation Constraints

Role of Constraints

Constraints can automate complex animation relationships, reducing the workload of manual keyframing.

# Transform Constraints
transform_constraints = {
    'COPY_LOCATION': {
        'name': 'Copy Location',
        'use': 'Make an object follow another object's location',
        'axes': ['X', 'Y', 'Z'],
        'influence': 1.0
    },
    'COPY_ROTATION': {
        'name': 'Copy Rotation',
        'use': 'Make an object follow another object's rotation',
        'order': 'XYZ'
    },
    'COPY_SCALE': {
        'name': 'Copy Scale',
        'use': 'Make an object follow another object's scale'
    },
    'COPY_TRANSFORMS': {
        'name': 'Copy Transforms',
        'use': 'Copy complete transform information'
    }
}

8.8.2 Tracking Constraints

# Tracking Constraint Settings
tracking_constraints = {
    'TRACK_TO': {
        'target': 'target_object',
        'track_axis': 'TRACK_Y',      # Tracking axis
        'up_axis': 'UP_Z',            # Up axis
        'use_target_z': False         # Use target Z-axis
    },
    'LOCKED_TRACK': {
        'target': 'target_object',
        'track_axis': 'TRACK_Y',
        'lock_axis': 'LOCK_Z'         # Lock axis
    }
}

8.8.3 Relationship Constraints

# Relationship Constraint Example
relationship_constraints = {
    'CHILD_OF': {
        'name': 'Child Of Constraint',
        'target': 'parent_object',
        'use_location': True,
        'use_rotation': True,
        'use_scale': False
    },
    'FLOOR': {
        'name': 'Floor Constraint',
        'target': 'floor_object',
        'floor_location': 'FLOOR_Y',
        'use_rotation': False
    }
}

8.9 Practical Animation Projects

8.9.1 Bouncing Ball Animation

Goal: Create a realistic bouncing ball animation

Animation Principles Applied:

Squash and Stretch: The ball deforms on contact with the ground
Slow In and Slow Out: Acceleration and deceleration under gravity
Arcs: Parabolic trajectory

# Bouncing Ball Keyframe Settings
bouncing_ball_keyframes = {
    'frame_1': {
        'location': (0, 0, 5),
        'scale': (1, 1, 1)
    },
    'frame_12': {  # Contact with ground
        'location': (0, 0, 0.5),
        'scale': (1.3, 1.3, 0.7)  # Squash deformation
    },
    'frame_15': {  # Leaving the ground
        'location': (0, 0, 0.5),
        'scale': (0.8, 0.8, 1.2)  # Stretch deformation
    },
    'frame_24': {  # Highest point
        'location': (0, 0, 3),
        'scale': (1, 1, 1)
    }
}

8.9.2 Pendulum Animation

Goal: Create a physically accurate pendulum motion

Key Techniques:

Use a sine function to drive rotation
Adjust swing amplitude and period
Add damping effect to simulate real physics

# Pendulum Driver Settings
pendulum_driver = {
    'expression': 'sin(frame * 0.1) * 30',  # Sine swing
    'amplitude': 30,      # Swing amplitude (degrees)
    'frequency': 0.1,     # Swing frequency
    'damping': 0.98      # Damping coefficient
}

8.9.3 Gear Transmission Animation

Goal: Create an interconnected gear transmission system

Key Techniques:

Use drivers to establish gear ratio relationships
Precisely calculate speed ratios
Synchronize the motion of multiple gears

# Gear Transmission Settings
gear_system = {
    'main_gear': {
        'teeth': 20,
        'rotation_speed': 1.0  # Main gear speed
    },
    'secondary_gear': {
        'teeth': 10,
        'rotation_speed': 2.0,  # Speed = 20/10 = 2x
        'driver_expression': 'main_gear_rotation * (20/10)'
    }
}

8.10 Animation Optimization and Output

8.10.1 Animation Performance Optimization

Performance Considerations

Complex animations can affect playback performance and need proper optimization.

# Performance Optimization Strategies
performance_optimization = {
    'keyframe_reduction': 'Reduce unnecessary keyframes',
    'simplify_curves': 'Simplify animation curves',
    'use_proxy_objects': 'Use proxy objects for preview',
    'disable_modifiers': 'Disable modifiers during preview',
    'reduce_subdivision': 'Lower subdivision levels',
    'viewport_shading': 'Use simple shading modes'
}

8.10.2 Animation Caching

# Point Cache Settings
point_cache_settings = {
    'frame_start': 1,
    'frame_end': 250,
    'step': 1,
    'use_disk_cache': True,
    'use_library_path': False,
    'filepath': '//cache/'
}

8.10.3 Animation Export

# FBX Animation Export Settings
fbx_animation_export = {
    'use_selection': False,          # Export all
    'use_active_collection': False,  # Use active collection
    'global_scale': 1.0,            # Global scale
    'apply_unit_scale': True,       # Apply unit scale
    'bake_space_transform': False,  # Bake space transform
    'object_types': {'ARMATURE', 'MESH'},  # Object types
    'use_mesh_modifiers': True,     # Use mesh modifiers
    'bake_anim': True,              # Bake animation
    'bake_anim_use_all_bones': True, # Bake all bones
    'bake_anim_use_nla_strips': True, # Bake NLA strips
    'bake_anim_step': 1.0,          # Bake step
    'bake_anim_simplify_factor': 1.0 # Simplify factor
}

8.11 Shortcut Summary

8.11.1 Animation Playback Controls

Shortcut	Function	Notes
`Spacebar`	Play/Pause	Most common
`←` `→`	Previous/Next Frame	Precise browsing
`Shift + ←` `→`	Jump to Keyframe	Quick navigation
`Home`	Go to Frame 1	Reset playback
`End`	Go to Last Frame	End position

8.11.2 Keyframe Operations

Shortcut	Function	Frequency of Use
`I`	Insert Keyframe	Very High
`Shift + I`	Delete Keyframe	High
`Alt + I`	Clear Keyframe	Medium
`Ctrl + D`	Duplicate Keyframe	Medium
`T`	Set Interpolation Type	High

8.11.3 Graph Editor

Shortcut	Function	Description
`G`	Move Control Point	Adjust time/value
`S`	Scale Control Point	Adjust slope
`R`	Rotate Control Point	Adjust angle
`H`	Set Handle Type	Auto/Vector/Aligned
`V`	Set Handle Type	Quick set

Chapter Summary

This chapter systematically covered the basics of 3D animation production:

Animation Principles: Mastered the basic principles of traditional animation and the characteristics of 3D animation
Keyframe System: Learned to create, edit, and manage keyframes
Animation Curves: Mastered using the Graph Editor for precise animation control
Advanced Techniques: Learned about path animation, shape keys, drivers, etc.
Constraint System: Learned to use constraints to automate complex animation relationships
Practical Projects: Improved animation production skills through practical cases

Animation production is a skill area that requires a lot of practice. It is recommended to observe the laws of motion in the real world and try to express them through animation. In the next chapter, we will learn about character rigging and armature systems to prepare for character animation.

Continuous Improvement

The essence of animation is to express emotions and stories; technology is just a means. Study the action design of excellent animated works to understand the emotional expression behind the animation.