Unity Game Development Concepts

Rigging and Animation

• Rigging a model means setting up an internal skeleton that can be manipulated by an animator to move the model.
• To have an animated object in Unity, you need:
  • A rigged model
  • Animation for the rigged model
  • An animator component on the Game Object
  • An Animator Controller assigned to the Animator
• The Animator Controller holds all the separate animations and acts as an interface for your code.

Lighting

• There are three basic light types in Unity:
  • Directional (e.g. sun)
  • Point (e.g. hanging light bulb)
  • Spot (e.g. spotlights)
• Directional lights cast light evenly across the scene and don't fade at a distance.
• Point lights cast light from a single point outward evenly in a sphere and fade out the further you get from the source.
• Spot lights cast light from a single point outward in a cone shape and fade out the further you get from the source.

GameObjects

• The DontDestroyOnLoad function can be used to move a GameObject between scenes without destroying it.
• Example: DontDestroyOnLoad(gameObject);
• A singleton is a code pattern that ensures only one instance of a GameObject exists.
• Example: public class ScriptName : MonoBehaviour { static scriptName instance; ... }

Physics

• 3D physics is similar to 2D physics, with the addition of the Z axis.
• 3D and 2D physics do not collide.
• By default, Unity uses Discrete collision detection, which checks for collisions once per frame.
• Continuous collision detection checks for collisions once per frame and also checks in between frames, but takes a big performance hit.

Physics Materials

• Dynamic Friction is the friction of a moving body.
• Static Friction is how much friction must be overcome to start an object moving.
• Bounciness determines how much an object should bounce.

First Person Controls and Materials

• To rotate a game object towards the mouse's current position, you must first convert it to the same coordinate space.
• PlayerPrefs is not safe for saving important data.
• Materials use shaders to set properties of how the object will be drawn.
• Shaders can use various images, such as textures, provided by an artist.
• A normal map is a flat image that can be applied and interpreted in the shader.

2D and 3D

• Unity was built for 3D, but 2D was supported in Unity 4.
• 2D uses Orthographic Camera, while 3D uses Perspective Camera.
• 2D uses sprites, while 3D uses models.
• 2D lighting is calculated on sprites, while 3D lighting is calculated on models.
• Every 3D model is made up of lots of smaller flat triangles, known as polygons.
• Polygons are used because they are the most efficient for graphics calculations, textures, lighting, and shadows.

3D Animation

• Skinned Mesh Animation is the practice of moving each vertex of a 3D model relative to an internal skeleton.
• Rigging is the process of setting up how each point should move relative to the skeleton inside.