[OpenGL]从零开始写一个Android平台下的全景视频播放器——2.2 使用GLSurfaceView和MediaPlayer播放一个平面视频（中）

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更新着色器代码

因为使用了，需要更新着色器代码 
fragment_shader.glsl

#extension GL_OES_EGL_image_external : requireprecision mediump float;varying vec2 vTexCoord;uniform samplerExternalOES sTexture;void main() {    gl_FragColor=texture2D(sTexture, vTexCoord);}

在这里，我们使用samplerExternalOES代替之前的sampler2D,需要注意的是第一行的注解是必须加上的 
这个samplerExternalOES有什么用呢？ 其实就是之前说的和surfaceTexture配合进行纹理更新和格式转换，具体的可以直接看OpenGL ES的官方文档,我截了一段供大家参考(估计也没什么人看。。): 

vertex_shader.glsl

attribute vec4 aPosition;attribute vec4 aTexCoord;varying vec2 vTexCoord;uniform mat4 uMatrix;uniform mat4 uSTMatrix;void main() {    vTexCoord = (uSTMatrix * aTexCoord).xy;    gl_Position = uMatrix*aPosition;}

在顶点着色器中，需要加入对应的uSTMatrix，并且aTexCoord要改成长度为4的向量，以便于做乘法操作。

更新GLRenderer

在GLRenderer中，用类似的方法获取uSTMMatrixHandle

uSTMMatrixHandle = GLES20.glGetUniformLocation(programId, "uSTMatrix");

每次绘制的时候，将mSTMatrix用类似的方法传给OpenGL：

GLES20.glUniformMatrix4fv(uSTMMatrixHandle, 1, false, mSTMatrix, 0);

因为用了扩展纹理，所以我们绑定的纹理类型也要做修改：

GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,textureId);

我们刚才只是设定了一个boolean来表示可以更新纹理了，却没有具体操作，所以在onDrawFrame最开始加入如下代码

synchronized (this){    if (updateSurface){        surfaceTexture.updateTexImage();        surfaceTexture.getTransformMatrix(mSTMatrix);        updateSurface = false;    }}

为了后续操作方便，我将绘制三角形的方式换成了绘制三角形带。

因为目前写的代码已经比较长了，我会在最后直接贴出GLRenderer的代码，如果遇到了什么问题，可以对照着看一下。

那我们来试一下吧，直接指定一个视频源，看看能不能正常显示（别忘了声明权限哦）：

glSurfaceView.setRenderer(new GLRenderer(this, Environment.getExternalStorageDirectory().getPath()+"/360Video/video.mp4"));

这是一个2:1的全景视频，可以看到全景视频被压扁了，而且画面也是倒过来的，如果按一下HOME键，会发现视频并不会自己停止播放，我们会在下一节来解决屏幕尺寸适应和播放器生命周期的问题。

GLRenderer.java

package com.martin.ads.panoramaopengltutorial;import android.content.Context;import android.graphics.SurfaceTexture;import android.media.AudioManager;import android.media.MediaPlayer;import android.net.Uri;import android.opengl.GLES11Ext;import android.opengl.GLES20;import android.opengl.GLSurfaceView;import android.opengl.Matrix;import android.util.Log;import android.view.Surface;import java.io.IOException;import java.nio.ByteBuffer;import java.nio.ByteOrder;import java.nio.FloatBuffer;import java.nio.ShortBuffer;import javax.microedition.khronos.egl.EGLConfig;import javax.microedition.khronos.opengles.GL10;/** * Created by Ads on 2016/11/13. */public class GLRenderer implements GLSurfaceView.Renderer, SurfaceTexture.OnFrameAvailableListener {    private static final String TAG = "GLRenderer";    private Context context;    private int aPositionHandle;    private int programId;    private FloatBuffer vertexBuffer;    private final float[] vertexData = {            1f,1f,0f,            -1f,1f,0f,            1f,-1f,0f,            -1f,-1f,0f    };    private final float[] projectionMatrix=new float[16];    private int uMatrixHandle;    private final float[] textureVertexData = {            1f,0f,            0f,0f,            1f,1f,            0f,1f    };    private FloatBuffer textureVertexBuffer;    private int uTextureSamplerHandle;    private int aTextureCoordHandle;    private int textureId;    private SurfaceTexture surfaceTexture;    private MediaPlayer mediaPlayer;    private float[] mSTMatrix = new float[16];    private int uSTMMatrixHandle;    private boolean updateSurface;    private boolean playerPrepared;    private int screenWidth,screenHeight;    public GLRenderer(Context context,String videoPath) {        this.context = context;        playerPrepared=false;        synchronized(this) {            updateSurface = false;        }        vertexBuffer = ByteBuffer.allocateDirect(vertexData.length * 4)                .order(ByteOrder.nativeOrder())                .asFloatBuffer()                .put(vertexData);        vertexBuffer.position(0);        textureVertexBuffer = ByteBuffer.allocateDirect(textureVertexData.length * 4)                .order(ByteOrder.nativeOrder())                .asFloatBuffer()                .put(textureVertexData);        textureVertexBuffer.position(0);        mediaPlayer=new MediaPlayer();        try{            mediaPlayer.setDataSource(context, Uri.parse(videoPath));        }catch (IOException e){            e.printStackTrace();        }        mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);        mediaPlayer.setLooping(true);    }    @Override    public void onSurfaceCreated(GL10 gl, EGLConfig config) {        String vertexShader = ShaderUtils.readRawTextFile(context, R.raw.vertex_shader);        String fragmentShader= ShaderUtils.readRawTextFile(context, R.raw.fragment_shader);        programId=ShaderUtils.createProgram(vertexShader,fragmentShader);        aPositionHandle= GLES20.glGetAttribLocation(programId,"aPosition");        uMatrixHandle=GLES20.glGetUniformLocation(programId,"uMatrix");        uSTMMatrixHandle = GLES20.glGetUniformLocation(programId, "uSTMatrix");        uTextureSamplerHandle=GLES20.glGetUniformLocation(programId,"sTexture");        aTextureCoordHandle=GLES20.glGetAttribLocation(programId,"aTexCoord");        int[] textures = new int[1];        GLES20.glGenTextures(1, textures, 0);        textureId = textures[0];        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, textureId);        ShaderUtils.checkGlError("glBindTexture mTextureID");        GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER,                GLES20.GL_NEAREST);        GLES20.glTexParameterf(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER,                GLES20.GL_LINEAR);        surfaceTexture = new SurfaceTexture(textureId);        surfaceTexture.setOnFrameAvailableListener(this);        Surface surface = new Surface(surfaceTexture);        mediaPlayer.setSurface(surface);        surface.release();        if (!playerPrepared){            try {                mediaPlayer.prepare();                playerPrepared=true;            } catch (IOException t) {                Log.e(TAG, "media player prepare failed");            }            mediaPlayer.start();            playerPrepared=true;        }    }    @Override    public void onSurfaceChanged(GL10 gl, int width, int height) {        screenWidth=width; screenHeight=height;        float ratio=width>height?                (float)width/height:                (float)height/width;        if (width>height){            Matrix.orthoM(projectionMatrix,0,-ratio,ratio,-1f,1f,-1f,1f);        }else Matrix.orthoM(projectionMatrix,0,-1f,1f,-ratio,ratio,-1f,1f);    }    @Override    public void onDrawFrame(GL10 gl) {        GLES20.glClear( GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);        synchronized (this){            if (updateSurface){                surfaceTexture.updateTexImage();                surfaceTexture.getTransformMatrix(mSTMatrix);                updateSurface = false;            }        }        GLES20.glUseProgram(programId);        GLES20.glUniformMatrix4fv(uMatrixHandle,1,false,projectionMatrix,0);        GLES20.glUniformMatrix4fv(uSTMMatrixHandle, 1, false, mSTMatrix, 0);        vertexBuffer.position(0);        GLES20.glEnableVertexAttribArray(aPositionHandle);        GLES20.glVertexAttribPointer(aPositionHandle, 3, GLES20.GL_FLOAT, false,                12, vertexBuffer);        textureVertexBuffer.position(0);        GLES20.glEnableVertexAttribArray(aTextureCoordHandle);        GLES20.glVertexAttribPointer(aTextureCoordHandle,2,GLES20.GL_FLOAT,false,8,textureVertexBuffer);        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);        GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,textureId);        GLES20.glUniform1i(uTextureSamplerHandle,0);        GLES20.glViewport(0,0,screenWidth,screenHeight);        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);    }    @Override    synchronized public void onFrameAvailable(SurfaceTexture surface) {        updateSurface = true;    }}