Overview
This lecture introduces physics engines in video games, explaining their basic function, common calculations, and the ways in which games simulate real-world physical phenomena for gameplay.
Introduction to Physics Engines
- A physics engine is software used to simulate physical phenomena in video games.
- Physics engines approximate real-world physics to run calculations quickly and maintain player interest.
- The engine processes user input, updates object positions and interactions, and displays results (rendering).
Basic Physics Calculations in Games
- Early games like Pong use simple physics, such as calculating the angle of incidence and angle of reflection.
- The angle of incidence is the angle at which an object approaches a surface; the angle of reflection is equal to it.
- These principles also apply in games like pool/billiards and simple 2D games.
Acceleration and Gravity in Games
- Objects falling due to gravity accelerate at 9.8 m/s² (32 ft/s²) on Earth.
- Speed increases each second an object falls: after one second, 32 ft/s; after two seconds, 64 ft/s, etc.
- Calculations can determine distance fallen, velocity at a given moment, and average velocity.
Ballistic Trajectory and Jumping Mechanics
- Ballistic trajectory calculations apply to jumping in games (e.g., platformers).
- After jumping, gravity pulls a character back toward the ground; distance and height depend on angle and force.
- Jumping at a 45-degree angle usually yields maximum horizontal distance with equal initial force.
- Jumping at 30° or 60° produces similar, but shorter, distances due to angle effects on motion.
Simplifications in Game Physics
- Video games simplify physics by ignoring minor factors like friction, altitude effects on gravity, or Earth's spin.
- Simple, fast equations are used so gameplay remains smooth and responsive.
Physics Engines in Action: Example
- In games like Super Mario, physics engines determine jump height, airtime, and where/when the character lands.
- Collisions with objects add complexity, requiring the engine to detect and handle these events.
Key Terms & Definitions
- Physics Engine — Software for simulating physical interactions and movement in games.
- Angle of Incidence — The angle at which an object approaches a surface.
- Angle of Reflection — The angle at which an object bounces off a surface, equal to the angle of incidence.
- Acceleration — The rate of change of velocity; for gravity, 9.8 m/s² (32 ft/s²).
- Ballistic Trajectory — The curved path of an object under the influence of gravity.
- Render — The process of displaying updated positions and visuals on the screen.
Action Items / Next Steps
- No calculations or math required for this week.
- Review linked Wikipedia pages for further examples and explanations.
- Prepare for next lecture on advanced physics and applications in more complex games.