1 /* 2 * Copyright 2018 Google LLC All Rights Reserved. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.skar.examples.helloskar.rendering; 18 19 import android.content.Context; 20 import android.opengl.GLES20; 21 import android.util.Log; 22 23 import java.io.BufferedReader; 24 import java.io.IOException; 25 import java.io.InputStream; 26 import java.io.InputStreamReader; 27 28 /** 29 * Shader helper functions. 30 */ 31 public class ShaderUtil { 32 /** 33 * Converts a raw text file, saved as a resource, into an OpenGL ES shader. 34 * 35 * @param type The type of shader we will be creating. 36 * @param filename The filename of the asset file about to be turned into a shader. 37 * @return The shader object handler. 38 */ loadGLShader(String tag, Context context, int type, String filename)39 public static int loadGLShader(String tag, Context context, int type, String filename) 40 throws IOException { 41 String code = readRawTextFileFromAssets(context, filename); 42 int shader = GLES20.glCreateShader(type); 43 GLES20.glShaderSource(shader, code); 44 GLES20.glCompileShader(shader); 45 46 // Get the compilation status. 47 final int[] compileStatus = new int[1]; 48 GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compileStatus, 0); 49 50 // If the compilation failed, delete the shader. 51 if (compileStatus[0] == 0) { 52 Log.e(tag, "Error compiling shader: " + GLES20.glGetShaderInfoLog(shader)); 53 GLES20.glDeleteShader(shader); 54 shader = 0; 55 } 56 57 if (shader == 0) { 58 throw new RuntimeException("Error creating shader."); 59 } 60 61 return shader; 62 } 63 64 /** 65 * Checks if we've had an error inside of OpenGL ES, and if so what that error is. 66 * 67 * @param label Label to report in case of error. 68 * @throws RuntimeException If an OpenGL error is detected. 69 */ checkGLError(String tag, String label)70 public static void checkGLError(String tag, String label) { 71 int lastError = GLES20.GL_NO_ERROR; 72 // Drain the queue of all errors. 73 int error; 74 while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) { 75 Log.e(tag, label + ": glError " + error); 76 lastError = error; 77 } 78 if (lastError != GLES20.GL_NO_ERROR) { 79 throw new RuntimeException(label + ": glError " + lastError); 80 } 81 } 82 83 /** 84 * Converts a raw text file into a string. 85 * 86 * @param filename The filename of the asset file about to be turned into a shader. 87 * @return The context of the text file, or null in case of error. 88 */ readRawTextFileFromAssets(Context context, String filename)89 private static String readRawTextFileFromAssets(Context context, String filename) 90 throws IOException { 91 try (InputStream inputStream = context.getAssets().open(filename); 92 BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream))) { 93 StringBuilder sb = new StringBuilder(); 94 String line; 95 while ((line = reader.readLine()) != null) { 96 sb.append(line).append("\n"); 97 } 98 return sb.toString(); 99 } 100 } 101 } 102