音视频之 opengl 渲染图片

attribute vec4 a_Position;attribute vec2 a_TextureCoordinates;varying vec2 v_TextureCoordinates;
void main() {    v_TextureCoordinates = a_TextureCoordinates;    gl_Position = a_Position;}

precision mediump float ;uniform sampler2D u_TextureUnit;varying vec2 v_TextureCoordinates;
void main() {    gl_FragColor = texture2D(u_TextureUnit , v_TextureCoordinates);}

String vertexShaderSource = TextResourceReader.readTextFileFromResource(context, R.raw.texture_vertext_shader_java_1);String frgShaderSource = TextResourceReader.readTextFileFromResource(context, R.raw.texture_frament_shader_java_1);int vertextShader = ShaderHelper.compileVertextShader(vertexShaderSource);int fragmentShader = ShaderHelper.compileFragmentShader(frgShaderSource);program = ShaderHelper.linkProgram(vertextShader, fragmentShader);ShaderHelper.validatePrograme(program);glUseProgram(program);

uTextureUnitL = glGetUniformLocation(program, "u_TextureUnit");aPositionL = glGetAttribLocation(program, "a_Position");aTextureCoordinatesL = glGetAttribLocation(program, "a_TextureCoordinates");

final int[] textureObjectIds = new int[1];glGenTextures(1,textureObjectIds , 0);if(textureObjectIds[0] == 0){    Log.e("xhc" , "cant open opengl texture object ！");    return 0;}

//然后将图片加载成一个bitmapfinal BitmapFactory.Options options = new BitmapFactory.Options();options.inScaled = false;final Bitmap bitmap = BitmapFactory.decodeResource(context.getResources() , resourceId , options);if(bitmap == null){    Log.e("xhc" , "bitmap create faild ");    glDeleteTextures(1, textureObjectIds , 0);    return 0;}
//在使用这个新生成的纹理之前，我们需要告诉opengl纹理调用应该应用于这个纹理对象//第一个参数GL_TEXTURE_2D 告诉这个纹理是个二维的纹理，对应的id是 textureObjectIds[0]glBindTexture(GL_TEXTURE_2D , textureObjectIds[0]);

/** * 设置过滤器GL_TEXTURE_MIN_FILTER指缩小的情况选择GL_LINEAR_MIPMAP_LINEAR说明缩小使用三线性过滤 * GL_TEXTURE_MAG_FILTER 指放大的情况GL_LINEAR使用双线性过滤 */glTexParameteri(GL_TEXTURE_2D , GL_TEXTURE_MIN_FILTER , GL_LINEAR_MIPMAP_LINEAR);glTexParameteri(GL_TEXTURE_2D , GL_TEXTURE_MAG_FILTER , GL_LINEAR);

//加载位图数据到opengl中texImage2D(GL_TEXTURE_2D , 0 , bitmap,0);//释放位图，节约内存bitmap.recycle();//生成mip贴图glGenerateMipmap(GL_TEXTURE_2D);//解除纹理绑定，这里不是把纹理数据和纹理id解除绑定，只是为了让后面的操作不要操作到此纹理，如果就是想操作，再从新绑定即可glBindTexture(GL_TEXTURE_2D , 0);

//我们再来看看坐标，顶点坐标和纹理坐标都放在一起//注意顶点和纹理的坐标做好对应float[] tableVerticesTexture = {        //x, y , s , t        0f, 0f, 0.5f, 0.5f,        -1f, -1f, 0f, 1f,        1f, -1f, 1f, 1f,        1f, 1f, 1f, 0f,        -1f, 1f, 0f, 0f,        -1f, -1f, 0f, 1f,};

    private void setVertexAttribPointer(int dataOffset, int attributeLocation, int componetCount, int stride) {        vertexData.position(dataOffset);        glVertexAttribPointer(attributeLocation, componetCount, GL_FLOAT, false, stride, vertexData);        glEnableVertexAttribArray(attributeLocation);        vertexData.position(0);    }

//通过  glActiveTexture(GL_TEXTURE0);把活动的纹理单元设置成纹理单元0，//然后通过glBindTextture()把纹理绑定到这个单元。通过调用//glUniformli（uTextureUnitLocation ,0）把被选定的纹理单元传递给片段着色器中。 @Override    public void onDrawFrame(GL10 gl10) {        glClear(GL_COLOR_BUFFER_BIT);        glUseProgram(program);        //drawtexture        glActiveTexture(GL_TEXTURE0);        glBindTexture(GL_TEXTURE_2D, texttureId);       glUniform1i(uTextureUnitL, 0);        glDrawArrays(GL_TRIANGLE_FAN, 0, 6);    }