将一个SurfaceTexture内容复制到另一个SurfaceTexture中

可以使用OpenGL ES在Android中将一个SurfaceTexture的内容复制到另一个SurfaceTexture中。以下是实现此操作的基本步骤：

1.创建一个新的SurfaceTexture和相关的Surface。

SurfaceTexture surfaceTexture1 = new SurfaceTexture(0);
Surface surface1 = new Surface(surfaceTexture1);

SurfaceTexture surfaceTexture2 = new SurfaceTexture(0);
Surface surface2 = new Surface(surfaceTexture2);

2.使用第一个SurfaceTexture作为纹理绑定到OpenGL ES程序中。

int textureId;
GLES20.glGenTextures(1, textureId, 0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);

surfaceTexture1.setDefaultBufferSize(width, height);
surfaceTexture1.setOnFrameAvailableListener(new MyOnFrameAvailableListener());

Surface surface = new Surface(surfaceTexture1);

3.创建一个OpenGL ES程序，并将第一个SurfaceTexture作为输入纹理。

int program = GLES20.glCreateProgram();
int vertexShader = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
int fragmentShader = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);

GLES20.glAttachShader(program, vertexShader);
GLES20.glAttachShader(program, fragmentShader);
GLES20.glLinkProgram(program);
GLES20.glUseProgram(program);

int aPosition = GLES20.glGetAttribLocation(program, "aPosition");
int aTextureCoordinates = GLES20.glGetAttribLocation(program, "aTextureCoordinates");
int uTextureMatrix = GLES20.glGetUniformLocation(program, "uTextureMatrix");
int uTextureSampler = GLES20.glGetUniformLocation(program, "uTextureSampler");

FloatBuffer vertexBuffer = ByteBuffer.allocateDirect(4 * 2 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
vertexBuffer.put(new float[]{-1, -1, 1, -1, -1, 1, 1, 1}).position(0);

FloatBuffer textureCoordinatesBuffer = ByteBuffer.allocateDirect(4 * 2 * 4).order(ByteOrder.nativeOrder()).asFloatBuffer();
textureCoordinatesBuffer.put(new float[]{0, 0, 1, 0, 0, 1, 1, 1}).position(0);

GLES20.glVertexAttribPointer(aPosition, 2, GLES20.GL_FLOAT, false, 0, vertexBuffer);
GLES20.glVertexAttribPointer(aTextureCoordinates, 2, GLES20.GL_FLOAT, false, 0, textureCoordinatesBuffer);
GLES20.glEnableVertexAttribArray(aPosition);
GLES20.glEnableVertexAttribArray(aTextureCoordinates);

Matrix.setIdentityM(textureMatrix, 0);
GLES20.glUniformMatrix4fv(uTextureMatrix, 1, false, textureMatrix, 0);

GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);
GLES20.glUniform1i(uTextureSampler, 0);

4.在onFrameAvailable回调中更新第一个SurfaceTexture并将数据复制到第二个SurfaceTexture中。

class MyOnFrameAvailableListener implements SurfaceTexture.OnFrameAvailableListener {

    @Override
    public void onFrameAvailable(SurfaceTexture surfaceTexture) {
        surfaceTexture.updateTexImage();
        surfaceTexture.getTransformMatrix(textureMatrix);

        GLES20.glViewport(0, 0, width, height);
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

        surface2.attachToGLContext(textureId);
        surfaceTexture2.updateTexImage();
        surface2.detachFromGLContext();
    }
}

5.最后，您可以使用第二个SurfaceTexture来显示输出图像。

mRenderer = new MyRenderer(surfaceTexture2);
mSurfaceView = new GLSurfaceView(this);
mSurfaceView.setEGLContextClientVersion(2);
mSurfaceView.setRenderer(mRenderer);
setContentView(mSurfaceView);