1. Interactive Animation
Game Development
Interactive Animation
Yingcai Xiao

2. Video Game
Interactive Animation: user-> interface (look) -> action (feel) -> feedback (A/V, haptic)

3. Video Game
Display
User
Controller
Game (Software)

4. Video Game Display Device Driver (GDI) Input Device Driver
Game (Software)

5. Game Programming Components
The Gang of Four (G4) for Interactive Animation
Controller (Input)
Game Objects (Geometry and Attributes)
Dynamics (Key Frame Animation)
Event-driven Programming (EDP: connects inputs to animation scripts)

6. Game controllers: input devices
The evolution of input devices:
CLI (Commend Line Input)
GUI (Graphical User Interface)
NUI (Natural Interface)

7. Animation Animation: any change that has a visual effect.
Motion Dynamics: movements (geometry change)
Update Dynamics: attribute change (color, texture, …)
Others: camera position, lighting, rendering techniques, …

8. Key-frame Animation Defining key-frames
Inbetweening with interpolations:
Lerping (linear interpolation)
parabola interpolation

9. Key-frame Animation

10. Neighborhood skeletons: define interpolated shapes

11. Graphical languages P-curves (parametric representation of motion)

12. Animation Control
Explicit: animator provides a description of everything that occurs in the animation.
Tracking live action.
Procedural: movement computed by a procedure.
Actors (Object-oriented high-level procedural control)
Kinematics: positions and velocities of points.
Dynamics: physical laws that govern kinematics.
Physically based: cloth draping, plastics bending, …
Constraint-based: constraint movements.

13. Double Buffering Why? To reduce flickering How?
Draw to the invisible back buffer
Copy to the visible front buffer. (Btblt)==>very fast with HW assistance

14. Double Buffering – Pseudo Code
void Draw() {
useCanvas(bbfr);
DrawObjects();
useCanvas(SCREEN_CANVAS);
copyPixel(bbfr, viewing-rectagle); }

15. Separation of Development Tasks
The Gang of Four (G4) for Interactive Animation
Controller (Input)
Game Objects (Geometry and Attributes)
Dynamics (Key Frame Animation)
Event-driven Programming (EDP: connects inputs to animation scripts)

16. Two Aspects of Game Development
Look + Feel
Look: Appearance
Game Objects (Geometry and Attributes)
can be created by artists
though a visual interface like Blender and Maya
or download prebuilt ones online (e.g.

17. Two Aspects of Game Development
Feel: Controlled Animation
animation scripts
connected to input events via EDP
implemented by programmers
though a programming language
or a visual interface like Unity3D

18. Graphics HW and SW Layers
Application
Game
Graphics SW
Initialization
Utility
Game IDE
Application Library
OS GUI API
Event Loop
Game Engine
OS EQ Interface
Graphics Library
Graphics Engine
Event Queue
GDI OS
GPU
Graphics HW
Graphics Card