Unity 4.3 制作一个2D横版射击游戏(2)
在上一篇《Unity 4.3 制作一个2D横版射击游戏》时，已经完成一个基本的射击游戏了。在这一篇将继续完善。
1.视差卷轴效果
为了达到这种视差卷轴的效果，可以让背景层以不同的速度进行移动，越远的层，移动地越慢。如果操作得当，这可以造成深度的错觉，这将很酷，又是可以容易做到的效果。在这里存在两个滚动：
- 主角随着摄像机向前推进
- 背景元素除了摄像机的移动外，又以不同的速度移动
一个循环的背景将在水平滚动的时候，一遍又一遍的重复进行显示。现在添加一个新的层到场景中，来显示背景元素。现有的层如下：
如下图所示：
接下来，先实现下不带背景循环的滚动。创建一个脚本，命名为" ScrollingScript"，代码如下：
| Layer | Loop | Position |
| Background with the sky | Yes | (0, 0, 10) |
| Background (1st row of flying platforms) | No | (0, 0, 9) |
| Middleground (2nd row of flying platforms) | No | (0, 0, 5) |
| Foreground with players and enemies | No | (0, 0, 0) |
接下来，先实现下不带背景循环的滚动。创建一个脚本，命名为" ScrollingScript"，代码如下：
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using UnityEngine;
/// /// Parallax scrolling script that should be assigned to a layer /// public class ScrollingScript : MonoBehaviour { /// /// public Vector2 speed = new Vector2( 2, 2); /// /// public Vector2 direction = new Vector2(- 1, 0); /// /// public bool isLinkedToCamera = false; void Update() { // Movement Vector3 movement = new Vector3( speed.x * direction.x, speed.y * direction.y, 0); movement *= Time.deltaTime; transform.Translate(movement); // Move the camera if (isLinkedToCamera) { Camera.main.transform.Translate(movement); } } } |
将这个脚本附加到以下对象上，并且设置好其属性值，如下：
| Layer | Speed | Direction | Linked to Camera |
| 0 - Background | (1, 1) | (-1, 0, 0) | No |
| 1 - Background elements | (1.5, 1.5) | (-1, 0, 0) | No |
| 2 - Middleground | (2.5, 2.5) | (-1, 0, 0) | No |
| 3 - Foreground | (1, 1) | (1, 0, 0) | Yes |
现在添加更多的元素到场景上：
- 添加两个天空背景到0 - Background
- 添加一些小的平台到1 - Background elements
- 添加一些平台到2 - Middleground
- 添加更多的敌人到3 - Foreground，放置在摄像机的右边
接下来，实现无限背景。当左侧的背景对象远离了摄像机的左边缘，那么就将它移到右侧去，一直这样无限循环，如下图所示：
要做到检查的对象渲染器是否在摄像机的可见范围内，需要一个类扩展。创建一个C#文件，命名为"
RendererExtensions.cs"，代码如下：
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using UnityEngine;
public static class RendererExtensions { public static bool IsVisibleFrom( this Renderer renderer, Camera camera) { Plane[] planes = GeometryUtility.CalculateFrustumPlanes(camera); return GeometryUtility.TestPlanesAABB(planes, renderer.bounds); } } |
修改"
ScrollingScript"脚本文件，为如下：
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using System.Collections.Generic;
using System.Linq; using UnityEngine; /// /// Parallax scrolling script that should be assigned to a layer /// public class ScrollingScript : MonoBehaviour { /// /// public Vector2 speed = new Vector2( 10, 10); /// /// public Vector2 direction = new Vector2(- 1, 0); /// /// public bool isLinkedToCamera = false; /// /// public bool isLooping = false; /// /// private List // 3 - Get all the children void Start() { // For infinite background only if (isLooping) { // Get all the children of the layer with a renderer backgroundPart = new List for ( int i = 0; i < transform.childCount; i++) { Transform child = transform.GetChild(i); // Add only the visible children if (child.renderer != null) { backgroundPart.Add(child); } } // Sort by position. // Note: Get the children from left to right. // We would need to add a few conditions to handle // all the possible scrolling directions. backgroundPart = backgroundPart.OrderBy( t => t.position.x ).ToList(); } } void Update() { // Movement Vector3 movement = new Vector3( speed.x * direction.x, speed.y * direction.y, 0); movement *= Time.deltaTime; transform.Translate(movement); // Move the camera if (isLinkedToCamera) { Camera.main.transform.Translate(movement); } // 4 - Loop if (isLooping) { // Get the first object. // The list is ordered from left (x position) to right. Transform firstChild = backgroundPart.FirstOrDefault(); if (firstChild != null) { // Check if the child is already (partly) before the camera. // We test the position first because the IsVisibleFrom // method is a bit heavier to execute. if (firstChild.position.x < Camera.main.transform.position.x) { // If the child is already on the left of the camera, // we test if it's completely outside and needs to be // recycled. if (firstChild.renderer.IsVisibleFrom(Camera.main) == false) { // Get the last child position. Transform lastChild = backgroundPart.LastOrDefault(); Vector3 lastPosition = lastChild.transform.position; Vector3 lastSize = (lastChild.renderer.bounds.max - lastChild.renderer.bounds.min); // Set the position of the recyled one to be AFTER // the last child. // Note: Only work for horizontal scrolling currently. firstChild.position = new Vector3(lastPosition.x + lastSize.x, firstChild.position.y, firstChild.position.z); // Set the recycled child to the last position // of the backgroundPart list. backgroundPart.Remove(firstChild); backgroundPart.Add(firstChild); } } } } } } |
在
Start方法里，使用了LINQ将它们按X轴进行排序。将"
0 - Background"对象里的"
ScrollingScript"组件的"
Is Looping"属性勾选，现在运行，就可以看到视差卷轴的效果，如下图所示：
接下来，修改敌人脚本，让敌人静止不动，且无敌，直到摄像机看到它们。另外，当它们移出屏幕时，则立刻移除它们。修改"
EnemyScript"脚本，代码为如下：
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using UnityEngine;
/// /// Enemy generic behavior /// public class EnemyScript : MonoBehaviour { private bool hasSpawn; private MoveScript moveScript; private WeaponScript[] weapons; void Awake() { // Retrieve the weapon only once weapons = GetComponentsInChildren // Retrieve scripts to disable when not spawn moveScript = GetComponent } // 1 - Disable everything void Start() { hasSpawn = false; // Disable everything // -- collider collider2D.enabled = false; // -- Moving moveScript.enabled = false; // -- Shooting foreach (WeaponScript weapon in weapons) { weapon.enabled = false; } } void Update() { // 2 - Check if the enemy has spawned. if (hasSpawn == false) { if (renderer.IsVisibleFrom(Camera.main)) { Spawn(); } } else { // Auto-fire foreach (WeaponScript weapon in weapons) { if (weapon != null && weapon.enabled && weapon.CanAttack) { weapon.Attack( true); } } // 4 - Out of the camera ? Destroy the game object. if (renderer.IsVisibleFrom(Camera.main) == false) { Destroy(gameObject); } } } // 3 - Activate itself. private void Spawn() { hasSpawn = true; // Enable everything // -- Collider collider2D.enabled = true; // -- Moving moveScript.enabled = true; // -- Shooting foreach (WeaponScript weapon in weapons) { weapon.enabled = true; } } } |
现在运行的话，会发现主角永远看不到敌人，因为敌人也跟随者层移动了。解决方法，只需将"
3 - Foreground"层上的"
ScrollingScript"脚本移除掉即可。在游戏过程中，可以发现主角并不是限制在摄像机区域内的，可以随意离开摄像机，现在来修复这个问题。打开"
PlayerScript"脚本，在
Update方法里面添加如下代码：
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void Update()
{ // ... // 6 - Make sure we are not outside the camera bounds var dist = (transform.position - Camera.main.transform.position).z; var leftBorder = Camera.main.ViewportToWorldPoint( new Vector3( 0, 0, dist) ).x; var rightBorder = Camera.main.ViewportToWorldPoint( new Vector3( 1, 0, dist) ).x; var topBorder = Camera.main.ViewportToWorldPoint( new Vector3( 0, 0, dist) ).y; var bottomBorder = Camera.main.ViewportToWorldPoint( new Vector3( 0, 1, dist) ).y; transform.position = new Vector3( Mathf.Clamp(transform.position.x, leftBorder, rightBorder), Mathf.Clamp(transform.position.y, topBorder, bottomBorder), transform.position.z ); // End of the update method } |
2.粒子效果
制作一个爆炸的粒子，用于敌人或者主角被摧毁时进行显示。创建一个"
Particle System"，导入烟图片到
"
Textures
"文件夹，改变其"
Texture Type"为"
Texture"，并且勾选"
Alpha Is Transparent"属性，附加这个纹理到粒子上，将其拖动到粒子对象上，更改其Shader为"
Particles
"→"
Alpha Blended"，接着更改一些属性，如下所示：
| Category | Parameter name | Value |
| General | Duration | 1 |
| General | Max Particles | 15 |
| General | Start Lifetime | 1 |
| General | Start Color | Gray |
| General | Start Speed | 3 |
| General | Start Size | 2 |
| Emission | Bursts | 0 : 15 |
| Shape | Shape | Sphere |
| Color Over Lifetime | Color | See below (N°1) |
| Size Over Lifetime | Size | See below (N°2) |
其中
Color Over Lifetime要设置成在结束时，有个淡出的效果，如下图所示：
Size Over Lifetime选择一个递减曲线，如下图所示：
当调整完成后，取消勾选"
Looping"，现在粒子效果为如下：
保存成预制，命名为"
SmokeEffect"，放在"
Prefabs/Particles"文件夹下。现在创建另一个粒子，火焰效果，使用默认材质即可。其他设置如下：
| Category | Parameter name | Value |
| General | Looping | false |
| General | Duration | 1 |
| General | Max Particles | 10 |
| General | Start Lifetime | 1 |
| General | Start Speed | 0.5 |
| General | Start Size | 2 |
| Emission | Bursts | 0 : 10 |
| Shape | Shape | Box |
| Color Over Lifetime | Color | See below (N°1) |
其中
Color Over Lifetime要设置成有一个黄色到橙色的渐变，最后淡出，如下图所示：
粒子效果为：
这里创建了一个单例，可以让任何地方都可以产生烟和火焰的粒子。将这个脚本附加到"
Scripts"对象，设置其属性"Smoke Effect"和"Fire Effect"为对应的预制体。现在是时候调用这个脚本了，打开"
HealthScript"脚本文件，在
OnTriggerEnter方法里面，更新成如下代码：
保存成预制，命名为"
FireEffect"。创建一个脚本，命名为"
SpecialEffectsHelper"，代码如下：
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using UnityEngine;
/// /// Creating instance of particles from code with no effort /// public class SpecialEffectsHelper : MonoBehaviour { /// /// public static SpecialEffectsHelper Instance; public ParticleSystem smokeEffect; public ParticleSystem fireEffect; void Awake() { // Register the singleton if (Instance != null) { Debug.LogError( "Multiple instances of SpecialEffectsHelper!"); } Instance = this; } /// /// /// { // Smoke on the water instantiate(smokeEffect, position); // Tu tu tu, tu tu tudu // Fire in the sky instantiate(fireEffect, position); } /// /// /// private ParticleSystem instantiate(ParticleSystem prefab, Vector3 position) { ParticleSystem newParticleSystem = Instantiate( prefab, position, Quaternion.identity ) as ParticleSystem; // Make sure it will be destroyed Destroy( newParticleSystem.gameObject, newParticleSystem.startLifetime ); return newParticleSystem; } } |
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public Damage(
int damageCount)
{ // ... if (hp <= 0) { // 'Splosion! SpecialEffectsHelper.Instance.Explosion(transform.position); // Dead! Destroy(gameObject); } // ... } |
现在运行，射击敌人，可以看到如下效果：
3.音乐和音效
现在来添加一些声音。将声音资源放入"
Sounds"文件夹，取消勾选每一个声音的"
3D sound"属性，因为这是2D游戏。准备播放背景音乐，创建一个游戏对象，命名为"
Music"，其
Position为(0, 0, 0)，将背景音乐拖到这个对象上，然后勾选"
Mute"属性。因为音效总是在一定的时机进行播放，所以创建一个脚本文件，命名为"
SoundEffectsHelper"，代码如下：
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using UnityEngine;
using System.Collections; /// /// Creating instance of sounds from code with no effort /// public class SoundEffectsHelper : MonoBehaviour { /// /// public static SoundEffectsHelper Instance; public AudioClip explosionSound; public AudioClip playerShotSound; public AudioClip enemyShotSound; void Awake() { // Register the singleton if (Instance != null) { Debug.LogError( "Multiple instances of SoundEffectsHelper!"); } Instance = this; } public void MakeExplosionSound() { MakeSound(explosionSound); } public void MakePlayerShotSound() { MakeSound(playerShotSound); } public void MakeEnemyShotSound() { MakeSound(enemyShotSound); } /// /// /// { // As it is not 3D audio clip, position doesn't matter. AudioSource.PlayClipAtPoint(originalClip, transform.position); } } |
将此脚本附加到"
Scripts"对象上，然后设置其属性值，如下图所示：
接着，在"
HealthScript"脚本文件里，播放粒子效果后面，添加代码：
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SoundEffectsHelper.Instance.MakeExplosionSound();
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在"
PlayerScript"脚本文件里，代码
weapon.Attack(false);后面，添加代码：
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SoundEffectsHelper.Instance.MakePlayerShotSound();
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在"
EnemyScript"脚本文件里，代码
weapon.Attack(false);后面，添加代码：
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SoundEffectsHelper.Instance.MakeEnemyShotSound();
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现在运行，就可以听到声音了。
4.菜单
创建简单的菜单，以便游戏可以重新开始。导入背景图片和LOGO图片到
"
Textures
"文件夹的子文件夹"
Menu"。创建一个新的场景，命名为"Menu"。添加背景
Sprite对象，其Position为
(0, 0, 1)，Size为
(2, 2, 1)。添加LOGO的Sprite对象，其Position为
(0, 2, 0)，Size为
(0.75, 0.75, 1)。添加一个空对象，命名为"Scripts"，用来加载脚本。现在为这个启动画面，添加一个开始按钮。创建一个脚本文件，命名为"
MenuScript"，代码如下：
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using UnityEngine;
/// /// Title screen script /// public class MenuScript : MonoBehaviour { void OnGUI() { const int buttonWidth = 84; const int buttonHeight = 60; // Draw a button to start the game if ( GUI.Button( // Center in X, 2/3 of the height in Y new Rect( Screen.width / 2 - (buttonWidth / 2), ( 2 * Screen.height / 3) - (buttonHeight / 2), buttonWidth, buttonHeight ), "Start!" ) ) { // On Click, load the first level. // "Stage1" is the name of the first scene we created. Application.LoadLevel( "Stage1"); } } } |
将此脚本附加到"
Scripts"对象上。现在运行，可以
看到如下效果：
但是，点击按钮会崩溃，因为没有将
Stage1场景添加进来。打开"
File"→"
Build Settings"，将场景"
Menu"和"
Stage1"拖动到上面的"
Scenes In Build"里面。再次运行，就可以看到按钮正常切换场景了。当主角被摧毁时，需要可以重新开始游戏。创建一个脚本文件，命名为"
GameOverScript"，代码如下：
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using UnityEngine;
/// /// Start or quit the game /// public class GameOverScript : MonoBehaviour { void OnGUI() { const int buttonWidth = 120; const int buttonHeight = 60; if ( GUI.Button( // Center in X, 1/3 of the height in Y new Rect( Screen.width / 2 - (buttonWidth / 2), ( 1 * Screen.height / 3) - (buttonHeight / 2), buttonWidth, buttonHeight ), "Retry!" ) ) { // Reload the level Application.LoadLevel( "Stage1"); } if ( GUI.Button( // Center in X, 2/3 of the height in Y new Rect( Screen.width / 2 - (buttonWidth / 2), ( 2 * Screen.height / 3) - (buttonHeight / 2), buttonWidth, buttonHeight ), "Back to menu" ) ) { // Reload the level Application.LoadLevel( "Menu"); } } } |
在主角死亡的时候，调用这个脚本。打开"
PlayerScript"文件，添加如下代码：
现在运行，当死亡时，就会出现按钮，如下图所示：
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void OnDestroy()
{ // Game Over. // Add the script to the parent because the current game // object is likely going to be destroyed immediately. transform.parent.gameObject.AddComponent } |
本例子源代码附加资源
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