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本文為大家分享了Unity實(shí)現(xiàn)粒子光效導(dǎo)出成png序列幀的具體代碼,供大家參考,具體內(nèi)容如下
這個(gè)功能并不是很實(shí)用,不過(guò)美術(shù)同學(xué)有這樣的需求,那么就花了一點(diǎn)時(shí)間研究了下。
我們沒(méi)有使用Unity的引擎,但是做特效的同學(xué)找了一批Unity的粒子特效,希望導(dǎo)出成png序列幀的形式,然后我們的游戲來(lái)使用。這個(gè)就相當(dāng)于拿Unity做了特效編輯器的工作。這個(gè)并不是很“邪門(mén)”,因?yàn)橛没糜傲W樱蛘?dmax,差不多也是這個(gè)思路,只不過(guò)那些軟件提供了正規(guī)的導(dǎo)出功能,而Unity則沒(méi)有。
先上代碼
using UnityEngine; using UnityEditor; using System; using System.IO; using System.Collections; using System.Collections.Generic; public class ParticleExporter : MonoBehaviour { // Default folder name where you want the animations to be output public string folder = "PNG_Animations"; // Framerate at which you want to play the animation public int frameRate = 25; // export frame rate 導(dǎo)出幀率,設(shè)置Time.captureFramerate會(huì)忽略真實(shí)時(shí)間,直接使用此幀率 public float frameCount = 100; // export frame count 導(dǎo)出幀的數(shù)目,100幀則相當(dāng)于導(dǎo)出5秒鐘的光效時(shí)間。由于導(dǎo)出每一幀的時(shí)間很長(zhǎng),所以導(dǎo)出時(shí)間會(huì)遠(yuǎn)遠(yuǎn)長(zhǎng)于直觀的光效播放時(shí)間 public int screenWidth = 960; // not use 暫時(shí)沒(méi)用,希望可以直接設(shè)置屏幕的大小(即光效畫(huà)布的大?。? public int screenHeight = 640; public Vector3 cameraPosition = Vector3.zero; public Vector3 cameraRotation = Vector3.zero; private string realFolder = ""; // real folder where the output files will be private float originaltimescaleTime; // track the original time scale so we can freeze the animation between frames private float currentTime = 0; private bool over = false; private int currentIndex = 0; private Camera exportCamera; // camera for export 導(dǎo)出光效的攝像機(jī),使用RenderTexture public void Start() { // set frame rate Time.captureFramerate = frameRate; // Create a folder that doesn't exist yet. Append number if necessary. realFolder = Path.Combine(folder, name); // Create the folder if (!Directory.Exists(realFolder)) { Directory.CreateDirectory(realFolder); } originaltimescaleTime = Time.timeScale; GameObject goCamera = Camera.main.gameObject; if (cameraPosition != Vector3.zero) { goCamera.transform.position = cameraPosition; } if (cameraRotation != Vector3.zero) { goCamera.transform.rotation = Quaternion.Euler(cameraRotation); } GameObject go = Instantiate(goCamera) as GameObject; exportCamera = go.GetComponent<Camera>(); currentTime = 0; } void Update() { currentTime += Time.deltaTime; if (!over && currentIndex >= frameCount) { over = true; Cleanup(); Debug.Log("Finish"); return; } // 每幀截屏 StartCoroutine(CaptureFrame()); } void Cleanup() { DestroyImmediate(exportCamera); DestroyImmediate(gameObject); } IEnumerator CaptureFrame() { // Stop time Time.timeScale = 0; // Yield to next frame and then start the rendering // this is important, otherwise will have error yield return new WaitForEndOfFrame(); string filename = String.Format("{0}/{1:D04}.png", realFolder, ++currentIndex); Debug.Log(filename); int width = Screen.width; int height = Screen.height; //Initialize and render textures RenderTexture blackCamRenderTexture = new RenderTexture(width, height, 24, RenderTextureFormat.ARGB32); RenderTexture whiteCamRenderTexture = new RenderTexture(width, height, 24, RenderTextureFormat.ARGB32); exportCamera.targetTexture = blackCamRenderTexture; exportCamera.backgroundColor = Color.black; exportCamera.Render(); RenderTexture.active = blackCamRenderTexture; Texture2D texb = GetTex2D(); //Now do it for Alpha Camera exportCamera.targetTexture = whiteCamRenderTexture; exportCamera.backgroundColor = Color.white; exportCamera.Render(); RenderTexture.active = whiteCamRenderTexture; Texture2D texw = GetTex2D(); // If we have both textures then create final output texture if (texw && texb) { Texture2D outputtex = new Texture2D(width, height, TextureFormat.ARGB32, false); // we need to check alpha ourselves,because particle use additive shader // Create Alpha from the difference between black and white camera renders for (int y = 0; y < outputtex.height; ++y) { // each row for (int x = 0; x < outputtex.width; ++x) { // each column float alpha; alpha = texw.GetPixel(x, y).r - texb.GetPixel(x, y).r; alpha = 1.0f - alpha; Color color; if (alpha == 0) { color = Color.clear; } else { color = texb.GetPixel(x, y); } color.a = alpha; outputtex.SetPixel(x, y, color); } } // Encode the resulting output texture to a byte array then write to the file byte[] pngShot = outputtex.EncodeToPNG(); File.WriteAllBytes(filename, pngShot); // cleanup, otherwise will memory leak pngShot = null; RenderTexture.active = null; DestroyImmediate(outputtex); outputtex = null; DestroyImmediate(blackCamRenderTexture); blackCamRenderTexture = null; DestroyImmediate(whiteCamRenderTexture); whiteCamRenderTexture = null; DestroyImmediate(texb); texb = null; DestroyImmediate(texw); texb = null; System.GC.Collect(); // Reset the time scale, then move on to the next frame. Time.timeScale = originaltimescaleTime; } } // Get the texture from the screen, render all or only half of the camera private Texture2D GetTex2D() { // Create a texture the size of the screen, RGB24 format int width = Screen.width; int height = Screen.height; Texture2D tex = new Texture2D(width, height, TextureFormat.ARGB32, false); // Read screen contents into the texture tex.ReadPixels(new Rect(0, 0, width, height), 0, 0); tex.Apply(); return tex; } }
這里對(duì)幾個(gè)關(guān)鍵的知識(shí)點(diǎn)來(lái)做說(shuō)明:
1、整體思路是這樣的,Unity中調(diào)整好攝像機(jī),正常播放特效,然后每幀截屏,保存成我們需要的png序列幀。這個(gè)不僅僅是特效可以這么用,其實(shí)模型也可以。比如我們需要同屏顯示幾百上千人,或者是無(wú)關(guān)緊要的怪物、場(chǎng)景物件等等,就可以使用這個(gè)導(dǎo)出成2d的序列幀,可以大大提高效率,使一些不可能的情況變?yōu)榭赡堋?/p>
2、關(guān)于時(shí)間和幀率的控制。由于截屏所需要的時(shí)間遠(yuǎn)遠(yuǎn)大于幀間隔,所以光效如果是播放1秒,則導(dǎo)出時(shí)間可能超過(guò)一分鐘。Time.captureFrameRate可以設(shè)置幀率,設(shè)置后則忽略真實(shí)時(shí)間,光效、模型會(huì)按照幀率的時(shí)間來(lái)播放。這個(gè)接口恰好就是用在視頻錄制上的。
3、光效畫(huà)布控制。這個(gè)暫時(shí)沒(méi)有找到好的方法,由于是全屏幕截屏,所以Game窗口的大小就是光效畫(huà)布的大小。
4、通過(guò)調(diào)整攝像機(jī)的位置、旋轉(zhuǎn),控制光效的顯示信息。
5、截屏函數(shù)就是GetTex2D()。這里面最主要的是ReadPixels函數(shù)。需要注意,CaptureFrame函數(shù)必須要以協(xié)程的方式運(yùn)行,因?yàn)槔锩嬗幸痪鋣ield return new WaitForEndOfFrame();如果沒(méi)有這一句,會(huì)報(bào)一個(gè)錯(cuò)誤,大概意思就是ReadPixels不在DrawFrame里面運(yùn)行。
6、截屏?xí)r間消耗很大,所以需要在截屏開(kāi)始使用Time.timeScale=0暫停時(shí)間運(yùn)行,截屏后再恢復(fù)
7、注意截屏操作完成后清理各種資源,并進(jìn)行GC。否則內(nèi)存很有可能就不夠用了,截100幀圖片,內(nèi)存很有可能就兩三G了。
8、截屏的時(shí)候使用了兩個(gè)RenderTexture,分別繪制白底和黑底的圖片,然后根據(jù)這兩張圖片計(jì)算出alpha。如果不是光效其實(shí)可以不這么麻煩,直接把Camera的backgroundColor中的alpha設(shè)置為0就可以了。但是光效使用了特殊的shader,比如Additive,這里涉及到alpha blend。繪制光效時(shí)如果也這樣設(shè)置的話,導(dǎo)出的圖片沒(méi)有任何東西。所以必須要有實(shí)色背景。
以上就是本文的全部?jī)?nèi)容,希望對(duì)大家的學(xué)習(xí)有所幫助,也希望大家多多支持億速云。
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