update delta time algorithm

FlappyBird/app/src/main/jni/main.c

@@ -3,6 +3,15 @@
 #include "utils.h"
 #include "mouse.h"
 
+
+#define TARGET_FPS 60
+#define TARGET_FRAME_TIME (1.0f / TARGET_FPS)
+
+double g_Time = 0.0;
+float DeltaTime = 0.0f;
+double g_LastFrameTime = 0.0;
+
+
 static void handleAppCmd(struct android_app* app, int32_t cmd)
 {
     switch (cmd)
@@ -27,32 +36,40 @@ int32_t handle_input(struct android_app* app, AInputEvent* event)
     if (eventType == AINPUT_EVENT_TYPE_MOTION) 
     {
         int32_t action = AMotionEvent_getAction(event);
-        int32_t pointerIndex = (action & AMOTION_EVENT_ACTION_POINTER_INDEX_MASK) >> AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
-        int32_t pointerId = AMotionEvent_getPointerId(event, pointerIndex);
-        float x = AMotionEvent_getX(event, pointerIndex);
-        float y = AMotionEvent_getY(event, pointerIndex);
+        action &= AMOTION_EVENT_ACTION_MASK;
+        int whichsource = action >> AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
+        size_t pointerCount = AMotionEvent_getPointerCount(event);
+        float x = 0.0f;
+        float y = 0.0f;
         bool isDown = false;
         bool isReleased = false;
         bool isMoved = false;
+        int index;
 
-        switch (action & AMOTION_EVENT_ACTION_MASK) 
+        for (size_t i = 0; i < pointerCount; ++i)
         {
-        case AMOTION_EVENT_ACTION_DOWN:
-        case AMOTION_EVENT_ACTION_POINTER_DOWN:
-            isDown = true;
-            //Log("Touch down at (%f, %f)", x, y);
-            break;
-
-        case AMOTION_EVENT_ACTION_UP:
-        case AMOTION_EVENT_ACTION_POINTER_UP:
-            isReleased = true;
-            //Log("Touch up at (%f, %f)", x, y);
-            break;
-
-        case AMOTION_EVENT_ACTION_MOVE:
-            isMoved = true;
-            //Log("Touch move at (%f, %f)", x, y);
-            break;
+            x = AMotionEvent_getX(event, i);
+            y = AMotionEvent_getY(event, i);
+            index = AMotionEvent_getPointerId(event, i);
+
+            if (action == AMOTION_EVENT_ACTION_POINTER_DOWN || action == AMOTION_EVENT_ACTION_DOWN)
+            {
+                int id = index;
+                if (action == AMOTION_EVENT_ACTION_POINTER_DOWN && id != whichsource) continue;
+
+                isDown = true;
+            }
+            else if (action == AMOTION_EVENT_ACTION_POINTER_UP || action == AMOTION_EVENT_ACTION_UP || action == AMOTION_EVENT_ACTION_CANCEL)
+            {
+                int id = index;
+                if (action == AMOTION_EVENT_ACTION_POINTER_UP && id != whichsource) continue;
+
+                isReleased = true;
+            }
+            else if (action == AMOTION_EVENT_ACTION_MOVE)
+            {
+                isMoved = true;
+            }
         }
 
         MouseUpdate(&mouse, x, y, isDown, isReleased, isMoved);
@@ -66,12 +83,6 @@ int32_t handle_input(struct android_app* app, AInputEvent* event)
     return 0; //Return 0 if you are not processing the event
 }
 
-#define TARGET_FPS 60
-#define TARGET_FRAME_TIME (1.0f / TARGET_FPS)
-
-double g_Time = 0.0;
-float DeltaTime = 0.0f;
-
 void android_main(struct android_app* state)
 {
     state->onInputEvent = handle_input;
@@ -102,28 +113,21 @@ void android_main(struct android_app* state)
             struct timespec current_timespec;
             clock_gettime(CLOCK_MONOTONIC, &current_timespec);
             double current_time = (double)(current_timespec.tv_sec) + (current_timespec.tv_nsec / 1000000000.0);
+
+            // calc delta time
             DeltaTime = g_Time > 0.0 ? (float)(current_time - g_Time) : (float)(1.0f / 60.0f);
 
-            // fps limit
-            if (DeltaTime < TARGET_FRAME_TIME) 
+            // checking if enough time has passed for a new frame
+            if (current_time - g_LastFrameTime >= TARGET_FRAME_TIME)
             {
-                // calc time wait
-                double sleep_time = TARGET_FRAME_TIME - DeltaTime;
-                struct timespec sleep_spec;
-                sleep_spec.tv_sec = (time_t)sleep_time;
-                sleep_spec.tv_nsec = (long)((sleep_time - sleep_spec.tv_sec) * 1000000000.0);
-                nanosleep(&sleep_spec, NULL);
-
-                // update now time after wait
-                clock_gettime(CLOCK_MONOTONIC, &current_timespec);
-                current_time = (double)(current_timespec.tv_sec) + (current_timespec.tv_nsec / 1000000000.0);
-                DeltaTime = (float)(current_time - g_Time);
+                MainLoopStep();
+                MouseReset(&mouse);
+
+                // update time last frame
+                g_LastFrameTime = current_time;
             }
 
             g_Time = current_time;
-
-            MainLoopStep();
-            MouseReset(&mouse);
         }
     }
 }