content: /*
   * Copyright 2017 Google Inc. All Rights Reserved.
   * 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 org.example.viotester.ext_ar; // NOTE: changed package name
  
  import android.content.Context;
  import android.opengl.GLES20;
  import android.util.Log;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  
  /** Shader helper functions. */
  public class ShaderUtil {
      /**
       * Converts a raw text file, saved as a resource, into an OpenGL ES shader.
       *
       * @param type The type of shader we will be creating.
       * @param filename The filename of the asset file about to be turned into a shader.
       * @return The shader object handler.
       */
      public static int loadGLShader(String tag, Context context, int type, String filename)
              throws IOException {
          String code = readShaderFileFromAssets(context, filename);
          int shader = GLES20.glCreateShader(type);
          GLES20.glShaderSource(shader, code);
          GLES20.glCompileShader(shader);
  
          // Get the compilation status.
          final int[] compileStatus = new int[1];
          GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
  
          // If the compilation failed, delete the shader.
          if (compileStatus[0] == 0) {
              Log.e(tag, "Error compiling shader: " + GLES20.glGetShaderInfoLog(shader));
              GLES20.glDeleteShader(shader);
              shader = 0;
          }
  
          if (shader == 0) {
              throw new RuntimeException("Error creating shader.");
          }
  
          return shader;
      }
  
      /**
       * Checks if we've had an error inside of OpenGL ES, and if so what that error is.
       *
       * @param label Label to report in case of error.
       * @throws RuntimeException If an OpenGL error is detected.
       */
      public static void checkGLError(String tag, String label) {
          int lastError = GLES20.GL_NO_ERROR;
          // Drain the queue of all errors.
          int error;
          while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
              Log.e(tag, label + ": glError " + error);
              lastError = error;
          }
          if (lastError != GLES20.GL_NO_ERROR) {
              throw new RuntimeException(label + ": glError " + lastError);
          }
      }
  
      /**
       * Converts a raw shader file into a string.
       *
       * @param filename The filename of the shader file about to be turned into a shader.
       * @return The context of the text file, or null in case of error.
       */
      private static String readShaderFileFromAssets(Context context, String filename)
              throws IOException {
          try (InputStream inputStream = context.getAssets().open(filename);
               BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream))) {
              StringBuilder sb = new StringBuilder();
              String line;
              while ((line = reader.readLine()) != null) {
                  String[] tokens = line.split(" ", -1);
                  if (tokens[0].equals("#include")) {
                      String includeFilename = tokens[1];
                      includeFilename = includeFilename.replace("\"", "");
                      if (includeFilename.equals(filename)) {
                          throw new IOException("Do not include the calling file.");
                      }
                      sb.append(readShaderFileFromAssets(context, includeFilename));
                  } else {
                      sb.append(line).append("\n");
                  }
              }
              return sb.toString();
          }
      }
  }