Add gl file

app/src/main/java/com/hippo/gl/view/AnimationTime.java

@@ -0,0 +1,45 @@
+
+/*
+ * Copyright (C) 2012 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 com.hippo.gl.view;
+
+import android.os.SystemClock;
+
+//
+// The animation time should ideally be the vsync time the frame will be
+// displayed, but that is an unknown time in the future. So we use the system
+// time just after eglSwapBuffers (when GLSurfaceView.onDrawFrame is called)
+// as a approximation.
+//
+public class AnimationTime {
+    private static volatile long sTime;
+
+    // Sets current time as the animation time.
+    public static void update() {
+        sTime = SystemClock.uptimeMillis();
+    }
+
+    // Returns the animation time.
+    public static long get() {
+        return sTime;
+    }
+
+    public static long startTime() {
+        sTime = SystemClock.uptimeMillis();
+        return sTime;
+    }
+}