gt:         if ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
context: /*
   * Copyright (C) 2013 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package ml.easychad.lax.android.video;
  
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.nio.FloatBuffer;
  
  import android.annotation.TargetApi;
  import android.graphics.SurfaceTexture;
  import android.opengl.GLES11Ext;
  import android.opengl.GLES20;
  import android.opengl.Matrix;
  
  @TargetApi(16)
  public class TextureRenderer {
  
      private static final int FLOAT_SIZE_BYTES = 4;
      private static final int TRIANGLE_VERTICES_DATA_STRIDE_BYTES = 5 * FLOAT_SIZE_BYTES;
      private static final int TRIANGLE_VERTICES_DATA_POS_OFFSET = 0;
      private static final int TRIANGLE_VERTICES_DATA_UV_OFFSET = 3;
      private static final float[] mTriangleVerticesData = {
              -1.0f, -1.0f, 0, 0.f, 0.f,
              1.0f, -1.0f, 0, 1.f, 0.f,
              -1.0f, 1.0f, 0, 0.f, 1.f,
              1.0f, 1.0f, 0, 1.f, 1.f,
      };
      private FloatBuffer mTriangleVertices;
  
      private static final String VERTEX_SHADER =
              "uniform mat4 uMVPMatrix;\n" +
              "uniform mat4 uSTMatrix;\n" +
              "attribute vec4 aPosition;\n" +
              "attribute vec4 aTextureCoord;\n" +
              "varying vec2 vTextureCoord;\n" +
              "void main() {\n" +
              "  gl_Position = uMVPMatrix * aPosition;\n" +
              "  vTextureCoord = (uSTMatrix * aTextureCoord).xy;\n" +
              "}\n";
  
      private static final String FRAGMENT_SHADER =
              "#extension GL_OES_EGL_image_external : require\n" +
              "precision mediump float;\n" +
              "varying vec2 vTextureCoord;\n" +
              "uniform samplerExternalOES sTexture;\n" +
              "void main() {\n" +
              "  gl_FragColor = texture2D(sTexture, vTextureCoord);\n" +
              "}\n";
  
      private float[] mMVPMatrix = new float[16];
      private float[] mSTMatrix = new float[16];
      private int mProgram;
      private int mTextureID = -12345;
      private int muMVPMatrixHandle;
      private int muSTMatrixHandle;
      private int maPositionHandle;
      private int maTextureHandle;
      private int rotationAngle = 0;
  
      public TextureRenderer(int rotation) {
          rotationAngle = rotation;
          mTriangleVertices = ByteBuffer.allocateDirect(mTriangleVerticesData.length * FLOAT_SIZE_BYTES).order(ByteOrder.nativeOrder()).asFloatBuffer();
          mTriangleVertices.put(mTriangleVerticesData).position(0);
          Matrix.setIdentityM(mSTMatrix, 0);
      }
  
      public int getTextureId() {
          return mTextureID;
      }
  
      public void drawFrame(SurfaceTexture st, boolean invert) {
          checkGlError("onDrawFrame start");
          st.getTransformMatrix(mSTMatrix);
  
          if (invert) {
              mSTMatrix[5] = -mSTMatrix[5];
              mSTMatrix[13] = 1.0f - mSTMatrix[13];
          }
  
          GLES20.glUseProgram(mProgram);
          checkGlError("glUseProgram");
          GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
          GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, mTextureID);
          mTriangleVertices.position(TRIANGLE_VERTICES_DATA_POS_OFFSET);
          GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, TRIANGLE_VERTICES_DATA_STRIDE_BYTES, mTriangleVertices);
          checkGlError("glVertexAttribPointer maPosition");
          GLES20.glEnableVertexAttribArray(maPositionHandle);
          checkGlError("glEnableVertexAttribArray maPositionHandle");
          mTriangleVertices.position(TRIANGLE_VERTICES_DATA_UV_OFFSET);
          GLES20.glVertexAttribPointer(maTextureHandle, 2, GLES20.GL_FLOAT, false, TRIANGLE_VERTICES_DATA_STRIDE_BYTES, mTriangleVertices);
          checkGlError("glVertexAttribPointer maTextureHandle");
          GLES20.glEnableVertexAttribArray(maTextureHandle);
          checkGlError("glEnableVertexAttribArray maTextureHandle");
          GLES20.glUniformMatrix4fv(muSTMatrixHandle, 1, false, mSTMatrix, 0);
          GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mMVPMatrix, 0);
          GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
          checkGlError("glDrawArrays");
          GLES20.glFinish();
      }
  
      public void surfaceCreated() {
          mProgram = createProgram(VERTEX_SHADER, FRAGMENT_SHADER);
          if (mProgram == 0) {
              throw new RuntimeException("failed creating program");
          }
          maPositionHandle = GLES20.glGetAttribLocation(mProgram, "aPosition");
          checkGlError("glGetAttribLocation aPosition");
          if (maPositionHandle == -1) {
              throw new RuntimeException("Could not get attrib location for aPosition");
          }
          maTextureHandle = GLES20.glGetAttribLocation(mProgram, "aTextureCoord");
          checkGlError("glGetAttribLocation aTextureCoord");
          if (maTextureHandle == -1) {
              throw new RuntimeException("Could not get attrib location for aTextureCoord");
          }
          muMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
          checkGlError("glGetUniformLocation uMVPMatrix");
          if (muMVPMatrixHandle == -1) {
              throw new RuntimeException("Could not get attrib location for uMVPMatrix");
          }
          muSTMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uSTMatrix");
          checkGlError("glGetUniformLocation uSTMatrix");
          if (muSTMatrixHandle == -1) {
              throw new RuntimeException("Could not get attrib location for uSTMatrix");
          }
          int[] textures = new int[1];
          GLES20.glGenTextures(1, textures, 0);
          mTextureID = textures[0];
          GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, mTextureID);
          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);
          GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
          GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
          checkGlError("glTexParameter");
  
          Matrix.setIdentityM(mMVPMatrix, 0);
          if (rotationAngle != 0) {
              Matrix.rotateM(mMVPMatrix, 0, rotationAngle, 0, 0, 1);
          }
      }
  
      public void changeFragmentShader(String fragmentShader) {
          GLES20.glDeleteProgram(mProgram);
          mProgram = createProgram(VERTEX_SHADER, fragmentShader);
          if (mProgram == 0) {
              throw new RuntimeException("failed creating program");
          }
      }
  
      private int loadShader(int shaderType, String source) {
          int shader = GLES20.glCreateShader(shaderType);
          checkGlError("glCreateShader type=" + shaderType);
          GLES20.glShaderSource(shader, source);
          GLES20.glCompileShader(shader);
          int[] compiled = new int[1];
          GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compiled, 0);
          if (compiled[0] == 0) {
              GLES20.glDeleteShader(shader);
              shader = 0;
          }
          return shader;
      }
  
      private int createProgram(String vertexSource, String fragmentSource) {
          int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexSource);
          if (vertexShader == 0) {
              return 0;
          }
          int pixelShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentSource);
          if (pixelShader == 0) {
              return 0;
          }
          int program = GLES20.glCreateProgram();
          checkGlError("glCreateProgram");
          if (program == 0) {
              return 0;
          }
          GLES20.glAttachShader(program, vertexShader);
          checkGlError("glAttachShader");
          GLES20.glAttachShader(program, pixelShader);
          checkGlError("glAttachShader");
          GLES20.glLinkProgram(program);
          int[] linkStatus = new int[1];
          GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linkStatus, 0);
          if (linkStatus[0] != GLES20.GL_TRUE) {
              GLES20.glDeleteProgram(program);
              program = 0;
          }
          return program;
      }
  
      public void checkGlError(String op) {
          int error;
  