+
+ // FPS handling
+ // Approach: We use a ring buffer to store times (in ms) over a given
+ // amount of frames, then sum them to figure out the FPS.
+ uint32_t timestamp = SDL_GetTicks();
+ // This assumes the ring buffer size is a power of 2
+// ringBufferPointer = (ringBufferPointer + 1) & (RING_BUFFER_SIZE - 1);
+ // Doing it this way is better. Ring buffer size can be arbitrary then.
+ ringBufferPointer = (ringBufferPointer + 1) % RING_BUFFER_SIZE;
+ ringBuffer[ringBufferPointer] = timestamp - oldTimestamp;
+ uint32_t elapsedTime = 0;
+
+ for(uint32_t i=0; i<RING_BUFFER_SIZE; i++)
+ elapsedTime += ringBuffer[i];
+
+ // elapsedTime must be non-zero
+ if (elapsedTime == 0)
+ elapsedTime = 1;
+
+ // This is in frames per 10 seconds, so we can have 1 decimal
+ uint32_t framesPerSecond = (uint32_t)(((float)RING_BUFFER_SIZE / (float)elapsedTime) * 10000.0);
+ uint32_t fpsIntegerPart = framesPerSecond / 10;
+ uint32_t fpsDecimalPart = framesPerSecond % 10;
+ // If this is updated too frequently to be useful, we can throttle it down
+ // so that it only updates every 10th frame or so
+ statusBar()->showMessage(QString("%1.%2 FPS").arg(fpsIntegerPart).arg(fpsDecimalPart));
+ oldTimestamp = timestamp;