1 files changed, 99 insertions, 0 deletions
diff --git a/platform_tools/android/apps/skar_java/src/main/java/com/google/skar/examples/helloskar/rendering/ShaderUtil.java b/platform_tools/android/apps/skar_java/src/main/java/com/google/skar/examples/helloskar/rendering/ShaderUtil.java
new file mode 100644
index 0000000000..ce33a45966
--- /dev/null
+++ b/platform_tools/android/apps/skar_java/src/main/java/com/google/skar/examples/helloskar/rendering/ShaderUtil.java
@@ -0,0 +1,99 @@
+/*
+ * 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 com.google.skar.examples.helloskar.rendering;
+
+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 = readRawTextFileFromAssets(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 text file into a string.
+     *
+     * @param filename The filename of the asset file about to be turned into a shader.
+     * @return The context of the text file, or null in case of error.
+     */
+    private static String readRawTextFileFromAssets(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) {
+                sb.append(line).append("\n");
+            }
+            return sb.toString();
+        }
+    }
+}