android studio 创建的初始工程。

app/src/main/cpp/main.cpp

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+#include <jni.h>
+
+#include <game-activity/native_app_glue/android_native_app_glue.h>
+#include <game-activity/GameActivity.h>
+
+#include "AndroidOut.h"
+#include "Renderer.h"
+
+extern "C" {
+
+/*!
+ * Handles commands sent to this Android application
+ * @param pApp the app the commands are coming from
+ * @param cmd the command to handle
+ */
+void handle_cmd(android_app *pApp, int32_t cmd) {
+    switch (cmd) {
+        case APP_CMD_INIT_WINDOW:
+            // A new window is created, associate a renderer with it. You may replace this with a
+            // "game" class if that suits your needs. Remember to change all instances of userData
+            // if you change the class here as a reinterpret_cast is dangerous this in the
+            // android_main function and the APP_CMD_TERM_WINDOW handler case.
+            pApp->userData = new Renderer(pApp);
+            break;
+        case APP_CMD_TERM_WINDOW:
+            // The window is being destroyed. Use this to clean up your userData to avoid leaking
+            // resources.
+            //
+            // We have to check if userData is assigned just in case this comes in really quickly
+            if (pApp->userData) {
+                //
+                auto *pRenderer = reinterpret_cast<Renderer *>(pApp->userData);
+                pApp->userData = nullptr;
+                delete pRenderer;
+            }
+            break;
+        default:
+            break;
+    }
+}
+
+/*!
+ * Enable the motion events you want to handle; not handled events are
+ * passed back to OS for further processing. For this example case,
+ * only pointer and joystick devices are enabled.
+ *
+ * @param motionEvent the newly arrived GameActivityMotionEvent.
+ * @return true if the event is from a pointer or joystick device,
+ *         false for all other input devices.
+ */
+bool motion_event_filter_func(const GameActivityMotionEvent *motionEvent) {
+    auto sourceClass = motionEvent->source & AINPUT_SOURCE_CLASS_MASK;
+    return (sourceClass == AINPUT_SOURCE_CLASS_POINTER ||
+            sourceClass == AINPUT_SOURCE_CLASS_JOYSTICK);
+}
+
+/*!
+ * This the main entry point for a native activity
+ */
+void android_main(struct android_app *pApp) {
+    // Can be removed, useful to ensure your code is running
+    aout << "Welcome to android_main" << std::endl;
+
+    // Register an event handler for Android events
+    pApp->onAppCmd = handle_cmd;
+
+    // Set input event filters (set it to NULL if the app wants to process all inputs).
+    // Note that for key inputs, this example uses the default default_key_filter()
+    // implemented in android_native_app_glue.c.
+    android_app_set_motion_event_filter(pApp, motion_event_filter_func);
+
+    // This sets up a typical game/event loop. It will run until the app is destroyed.
+    do {
+        // Process all pending events before running game logic.
+        bool done = false;
+        while (!done) {
+            // 0 is non-blocking.
+            int timeout = 0;
+            int events;
+            android_poll_source *pSource;
+            int result = ALooper_pollOnce(timeout, nullptr, &events,
+                                          reinterpret_cast<void**>(&pSource));
+            switch (result) {
+                case ALOOPER_POLL_TIMEOUT:
+                    [[clang::fallthrough]];
+                case ALOOPER_POLL_WAKE:
+                    // No events occurred before the timeout or explicit wake. Stop checking for events.
+                    done = true;
+                    break;
+                case ALOOPER_EVENT_ERROR:
+                    aout << "ALooper_pollOnce returned an error" << std::endl;
+                    break;
+                case ALOOPER_POLL_CALLBACK:
+                    break;
+                default:
+                    if (pSource) {
+                        pSource->process(pApp, pSource);
+                    }
+            }
+        }
+
+        // Check if any user data is associated. This is assigned in handle_cmd
+        if (pApp->userData) {
+            // We know that our user data is a Renderer, so reinterpret cast it. If you change your
+            // user data remember to change it here
+            auto *pRenderer = reinterpret_cast<Renderer *>(pApp->userData);
+
+            // Process game input
+            pRenderer->handleInput();
+
+            // Render a frame
+            pRenderer->render();
+        }
+    } while (!pApp->destroyRequested);
+}
+}