详解Unity安卓共享纹理

//向unity发消息
UnityPlayer.UnitySendMessage("Main Camera", //gameobject的名字
                             "ChangeColor", //调用方法的名字
                             "");			//参数智能传字符串，没有参数则传空字符串

//通过该API来实例化java代码中对应的类
AndroidJavaObject jc = new AndroidJavaObject("com.xxx.xxx.UnityPlayer");
jo.Call("Test");//调用void Test()方法
jo.Call("Text1", msg);//调用string Test1(string str)方法
jo.Call("Text2", 1, 2);//调用int Test1(int x, int y)方法

@Override public void onPreviewFrame(byte[] data, Camera camera){
    // function trans data[] to Unity
}

// 创建单线程池，用于处理OpenGL纹理
private final ExecutorService mRenderThread = Executors.newSingleThreadExecutor();

private volatile EGLContext mSharedEglContext;
private volatile EGLConfig mSharedEglConfig;

// 被unity调用获取EGLContext,在Unity线程执行
public void setupOpenGL {
    Log.d(TAG, "setupOpenGL called by Unity ");

    // 获取Unity线程的EGLContext,EGLDisplay
    mSharedEglContext = EGL14.eglGetCurrentContext();
    if (mSharedEglContext == EGL14.EGL_NO_CONTEXT) {...}
    EGLDisplay sharedEglDisplay = EGL14.eglGetCurrentDisplay();
    if (sharedEglDisplay == EGL14.EGL_NO_DISPLAY) {...}
    
    // 获取Unity绘制线程的EGLConfig
    int[] numEglConfigs = new int[1];
    EGLConfig[] eglConfigs = new EGLConfig[1];
    if (!EGL14.eglGetConfigs(sharedEglDisplay, eglConfigs, 0, 
                             eglConfigs.length,numEglConfigs, 0)) {...}

    mSharedEglConfig = eglConfigs[0];
    mRenderThread.execute(new Runnable() {	// Java线程内
        @Override
        public void run() {
            // Java线程初始化OpenGL环境
            initOpenGL();
            // 生成OpenGL纹理ID
            int textures[] = new int[1];
            GLES20.glGenTextures(1, textures, 0);
            if (textures[0] == 0) {...}
            mTextureID = textures[0];
            mTextureWidth = 670;
            mTextureHeight = 670;
        }
    });
}

private void initOpenGL() {
    mEGLDisplay = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
    if (mEGLDisplay == EGL14.EGL_NO_DISPLAY) {...}

    int[] version = new int[2];
    if (!EGL14.eglInitialize(mEGLDisplay, version, 0, version, 1)) {...}

    int[] eglContextAttribList = new int[]{
        EGL14.EGL_CONTEXT_CLIENT_VERSION, 3, // 版本需要与Unity使用的一致
        EGL14.EGL_NONE
    };

    // 将Unity线程的EGLContext和EGLConfig作为参数,传递给eglCreateContext,
    // 创建Java线程的EGLContext,从而实现两个线程共享EGLContext
    mEglContext = EGL14.eglCreateContext(
        mEGLDisplay, mSharedEglConfig, mSharedEglContext,
        eglContextAttribList, 0);
    if (mEglContext == EGL14.EGL_NO_CONTEXT) {...}

    int[] surfaceAttribList = {
        EGL14.EGL_WIDTH, 64,
        EGL14.EGL_HEIGHT, 64,
        EGL14.EGL_NONE
    };

    // Java线程不进行实际绘制，因此创建PbufferSurface而非windowsurface
    // 将Unity线程的EGLConfig作为参数传递给eglCreatePbufferSurface
    // 创建Java线程的EGLSurface
    mEglSurface = EGL14.eglCreatePbufferSurface(mEGLDisplay, mSharedEglConfig, surfaceAttribList, 0);
    if (mEglSurface == EGL14.EGL_NO_SURFACE) {...}
    if (!EGL14.eglMakeCurrent(
        mEGLDisplay, mEglSurface, mEglSurface, mEglContext)) {...}

    GLES20.glFlush();
}

public class GLTexture : MonoBehaviour
{
    private AndroidJavaObject mGLTexCtrl;
    private int mTextureId;
    private int mWidth;
    private int mHeight;

    private void Awake(){
        // 实例化com.xxx.nativeandroidapp.GLTexture类的对象
        mGLTexCtrl = new AndroidJavaObject("com.xxx.nativeandroidapp.GLTexture");
        // 初始化OpenGL
        mGLTexCtrl.Call("setupOpenGL");
    }

    void Start(){
        BindTexture();
    }
    
    void BindTexture(){
        // 获取 Java 线程生成的纹理ID
        mTextureId = mGLTexCtrl.Call<int>("getStreamTextureID");
        if (mTextureId == 0) {...}
        mWidth = mGLTexCtrl.Call<int>("getStreamTextureWidth");
        mHeight = mGLTexCtrl.Call<int>("getStreamTextureHeight");
        // 创建纹理并绑定到当前GameObject上
        material.mainTexture = 
            Texture2D.CreateExternalTexture(
            	mWidth, mHeight, 
            	TextureFORMat.ARGB32, 
            	false, false, 
            	(IntPtr)mTextureId);
        // 更新纹理数据
        mGLTexCtrl.Call("updateTexture");
    }
}

public void updateTexture() {
    //Log.d(TAG,"updateTexture called by unity");
    mRenderThread.execute(new Runnable() { //java线程内
        @Override
        public void run() {
            String imageFilePath = "your own picture path"; //图片路径
            final Bitmap bitmap = BitmapFactory.decodeFile(imageFilePath);
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextureID);
            GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
            GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_NEAREST);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
            GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
            bitmap.recycle();//回收内存
        }
    });
}

private SurfaceTexture mSurfaceTexture; //camera preview
private GLTextureOES mTextureOES;       //GL_TEXTURE_EXTERNAL_OES
private GLTexture2D mUnityTexture;      //GL_TEXTURE_2D 用于在Unity里显示的贴图
private FBO mFBO;						//具体代码在GitHub仓库

public void openCamera() {
	......
    
    // 利用OpenGL生成OES纹理并绑定到mSurfaceTexture
    // 再把camera的预览数据设置显示到mSurfaceTexture，OpenGL就能拿到摄像头数据。
    mTextureOES = new GLTextureOES(UnityPlayer.currentActivity, 0,0);
    mSurfaceTexture = new SurfaceTexture(mTextureOES.getTextureID());
    mSurfaceTexture.setOnFrameAvailableListener(this);
    try {
        mCamera.setPreviewTexture(mSurfaceTexture);
    } catch (IOException e) {
        e.printStackTrace();
    }
    mCamera.startPreview();
}

public int updateTexture() {
    synchronized (this) {
        if (mFrameUpdated) { mFrameUpdated = false; }
        mSurfaceTexture.updateTexImage();
        int width = mCamera.getParameters().getPreviewSize().width;
        int height = mCamera.getParameters().getPreviewSize().height;

        // 根据宽高创建Unity使用的GL_TEXTURE_2D纹理
        if (mUnityTexture == null) {
            Log.d(TAG, "width = " + width + ", height = " + height);
            mUnityTexture = new GLTexture2D(UnityPlayer.currentActivity, width, height);
            mFBO = new FBO(mUnityTexture);
        }
        Matrix.setIdentityM(mMVPMatrix, 0);
        mFBO.FBOBegin();
        GLES20.glViewport(0, 0, width, height);
        mTextureOES.draw(mMVPMatrix);
        mFBO.FBOEnd();

        Point size = new Point();
        if (Build.VERSION.SDK_INT >= 17) {
            UnityPlayer.currentActivity.getWindowManager().getDefaultDisplay().getRealSize(size);
        } else {
            UnityPlayer.currentActivity.getWindowManager().getDefaultDisplay().getSize(size);
        }
        GLES20.glViewport(0, 0, size.x, size.y);

        return mUnityTexture.getTextureID();
    }
}

Shader "Unlit/CyberpunkShader"
{
	Properties
	{
		_MainTex("Base (RGB)", 2D) = "white" {}
		_Power("Power", Range(0,1)) = 1
	}
	SubShader
	{
		Tags { "RenderType" = "Opaque" }
		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"

			struct a2v 
			{
				float4 vertex : POSITION;
				float2 texcoord : TEXCOORD0;
			};

			struct v2f 
			{
				float4 vertex : SV_POSITION;
				half2 texcoord : TEXCOORD0;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			float _Power;

			v2f vert(a2v v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
				return o;
			}

			fixed4 frag(v2f i) : SV_Target
			{
				fixed4 baseTex = tex2D(_MainTex, i.texcoord);
				float3 xyz = baseTex.rgb;
				float oldx = xyz.x;
				float oldy = xyz.y;
				float add = abs(oldx - oldy)*0.5;
				float stepxy = step(xyz.y, xyz.x);
				float stepyx = 1 - stepxy;
				xyz.x = stepxy * (oldx + add) + stepyx * (oldx - add);
				xyz.y = stepyx * (oldy + add) + stepxy * (oldy - add);
				xyz.z = sqrt(xyz.z);
				baseTex.rgb = lerp(baseTex.rgb, xyz, _Power);
				return baseTex;
			}
			ENDCG
		}
	}
	Fallback off
}

// 创建读出的GL_TEXTURE_2D纹理
if (mUnityTextureCopy == null) {
    Log.d(TAG, "width = " + width + ", height = " + height);
    mUnityTextureCopy = new GLTexture2D(UnityPlayer.currentActivity, size.x, size.y);
    mFBOCopy = new FBO(mUnityTextureCopy);
}
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mUnityTextureCopy.mTextureID);
GLES20.glCopyTexSubImage2D(GLES20.GL_TEXTURE_2D, 0,0,0,0,0,size.x, size.y);
mFBOCopy.FBOBegin();
// //test是否是当前FBO
// GLES20.glClearColor(1,0,0,1);
// GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
// GLES20.glFinish();
int mImageWidth = size.x;
int mImageHeight = size.y;
Bitmap dest = Bitmap.createBitmap(mImageWidth, mImageHeight, Bitmap.Config.ARGB_8888);
final ByteBuffer buffer = ByteBuffer.allocateDirect(mImageWidth * mImageHeight * 4);
GLES20.glReadPixels(0, 0, mImageWidth, mImageHeight, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, buffer);
dest.copyPixelsFromBuffer(buffer);
dest = null;//断点
mFBOCopy.FBOEnd();