Introduction to Game Design, Prototyping, and Development: From Concept to Playable Game with Unity and C# by Jeremy Gibson

Author:Jeremy Gibson [Gibson, Jeremy]
Language: eng
Format: azw3
Publisher: Pearson Education
Published: 2014-07-04T04:00:00+00:00

* * *

1 using UnityEngine;

2 using System.Collections;

3 using System.Collections.Generic; // Necessary to use generic Lists

4

5 public class Boid : MonoBehaviour {

6 // This static List holds all Boid instances & is shared amongst them

7 static public List<Boid> boids;

8

9 // Note:This code does NOT use a Rigidbody. It handles velocity directly

10 public Vector3 velocity; // The current velocity

11 public Vector3 newVelocity; // The velocity for next frame

12 public Vector3 newPosition; // The position for next frame

13

14 public List<Boid> neighbors; // All nearby Boids

15 public List<Boid> collisionRisks; // All Boids that are too close

16 public Boid closest; // The single closest Boid

17

18 // Initialize this Boid on Awake()

19 void Awake () { // 1

20 // Define the boids List if it is still null

21 if (boids == null) { // 2

22 boids = new List<Boid>();

23 }

24 // Add this Boid to boids

25 boids.Add(this);

26

27 // Give this Boid instance a random position and velocity

28 Vector3 randPos = Random.insideUnitSphere * BoidSpawner.S.spawnRadius;

29 randPos.y = 0; // Flatten the Boid to only move in the XZ plane

30 this.transform.position = randPos;

31 velocity = Random.onUnitSphere;

32 velocity *= BoidSpawner.S.spawnVelocity;

33

34 // Initialize the two Lists

35 neighbors = new List<Boid>(); // 3

36 collisionRisks = new List<Boid>();

37

38 // Make this.transform a child of the Boids GameObject

39 this.transform.parent = GameObject.Find("Boids").transform; // 4

40

41 // Give the Boid a random color, but make sure it's not too dark

42 Color randColor = Color.black;

43 while ( randColor.r + randColor.g + randColor.b < 1.0f ) {

44 randColor = new Color(Random.value, Random.value, Random.value);

45 }

46 Renderer[] rends = gameObject.GetComponentsInChildren<Renderer>();

47 foreach ( Renderer r in rends ) {

48 r.material.color = randColor;

49 }

50

51 }

52

53 // Update is called once per frame

54 void Update () { // 5

55

56 // Get the list of nearby Boids (this Boid's neighbors)

57 List<Boid> neighbors = GetNeighbors(this); // 6

58

59 // Initialize newVelocity and newPosition to the current values

60 newVelocity = velocity;

61 newPosition = this.transform.position;

62

63 // Velocity Matching: This sets the velocity of the boid to be

64 // similar to that of its neighbors

65 Vector3 neighborVel = GetAverageVelocity( neighbors );

66 // Utilizes the fields set on the BoidSpawner.S Singleton

67 newVelocity += neighborVel * BoidSpawner.S.velocityMatchingAmt;

68

69 // Flock Centering: Move toward middle of neighbors

70 Vector3 neighborCenterOffset = GetAveragePosition( neighbors ) - this.transform.position;

71 newVelocity += neighborCenterOffset*BoidSpawner.S.flockCenteringAmt;

72

73 // Collision Avoidance: Avoid running into Boids that are too close

74 Vector3 dist;

75 if (collisionRisks.Count > 0) {

76 Vector3 collisionAveragePos=GetAveragePosition(collisionRisks);

77 dist = collisionAveragePos - this.transform.position;

78 newVelocity += dist * BoidSpawner.S.collisionAvoidanceAmt;

79 }

80

81 // Mouse Attraction - Move toward the mouse no matter how far away

82 dist = BoidSpawner.S.mousePos - this.transform.position;

83 if (dist.magnitude > BoidSpawner.S.mouseAvoidanceDist) {

84 newVelocity += dist * BoidSpawner.S.mouseAttractionAmt;

85 } else {

86 // If the mouse is too close, move away quickly!

87 newVelocity -= dist.normalized*BoidSpawner.S.mouseAvoidanceDist*BoidSpawner.S.mouseAvoidanceAmt;

88 }

89

90 // newVelocity & newPosition are ready, but wait until LateUpdate()

91 // to set them so that this Boid doesn't move before others have

92 // had a chance to calculate their new values.

93 }

94

95 // By allowing all Boids to Update() themselves before any Boids

96 // move, we avoid race conditions that could be caused by some Boids

97 // moving before others have decided where to go.

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