1. Department of nskinfo i-education
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CS2401- Computer Graphics
Computer Animation
Department of nskinfo i-education

2. Learning Objectives Raster Methods for Computer Animation
Design of Animation Sequences
Traditional Animation Techniques
General Computer-Animation Functions
Key-Frame Systems
Morphing
Simulating Accelerations
Motion Specification
Articulated Figure Animation
Periodic Motions
Animation in OpenGL

3. Computer Animation
Any time sequence of visual changes in a picture

4. Computer Animation Real-time animation Frame-by-frame animation
Each stage of the sequence is viewed as it is created
Useful in simulators
Frame-by-frame animation
Each frame of the motion is separately generated and stored
Used for movies

5. Raster Methods for Computer Animation
Double buffering: while the screen is being refreshed from one buffer, we construct the scene in the other buffer
Raster operations
Block transfers of rectangular arrays of pixel values
Often used in games

6. Design of Animation Sequences
Storyboard layout
Rough sketches
A list of basic ideas for the action
Object definitions
Each participant in the action
Basic shapes
Movements to be performed by each character and object
Key-frame specifications
Detailed drawing of the scene at a certain time in the animation sequence
Generation of in-between frames
Intermediate frames between the key frames

7. Traditional Animation Techniques
Squash and stretch
To simulate acceleration

8. Traditional Animation Techniques
Timing
Slow objects are simulated with more frames, while faster moving objects are displayed with fewer frames

9. Traditional Animation Techniques
Emphasizing object movements
Anticipation of coming motion – a cartoon character can lean forward before running
Follow-through actions – a hat can fly off a character that is stopped abruptly
Staging – focusing on an important part of a scene

10. General Computer-Animation Functions
Managing object motions
Generating views of objects
Producing camera motions
Generating in-between frames

11. Key-Frame Systems
Generate in-between frames from the user-specified key frames (two or more)
Complex scenes separated into individual components called cels

12. Morphing
Transformation of object shapes from one to another

13. Morphing Transforming a line segment added point key frame k
halfway frame
key frame k+1

14. Morphing Transforming a triangle into a quadrilateral added point
key frame k
halfway frame
key frame k+1

15. Motion Specification
Direct specification of geometric transformation (transformation matrix)
Equation of the path
Bouncing ball:

16. Articulated Figure Animation
Articulated figure: hierarchical structure composed of a set of rigid links that are connected at rotary joints
Basic technique for animating people and animals

17. Periodic Motions
Have to be sampled frequently enough (Nyquist frequency)

18. Animation in OpenGL Double buffering:
glutInitDisplayMode(GLUT_DOUBLE);
Swapping buffers:
glutSwapBuffers();
Continuous animation:
glutIdleFunc(animationFcn);

19. Example
prog13OGLAnimation.cpp