Initial commit

source/Game/GameTime.cpp

@@ -0,0 +1,76 @@
+
+#include <iostream>
+#include <Spectre/Game/GameTime.h>
+#include <Spectre/System/System.h>
+
+GameTime::GameTime(unsigned long updates_per_sec)
+{
+	m_acc = 0;
+	m_current = System::getMilliseconds();
+	m_lastUpdate = m_current;
+	setTimeStep(updates_per_sec);
+}
+
+double GameTime::getTimeStep() const
+{
+	return m_slice;
+}
+
+void GameTime::setTimeStep(unsigned long updates_per_sec)
+{
+	m_slice = (1000.0f / ((double) updates_per_sec));
+
+	reset();
+}
+
+unsigned long GameTime::getElapsed() const
+{
+	return m_current - m_lastUpdate;
+}
+
+bool GameTime::beginFrame()
+{
+	reset();
+
+	accumulateTime();
+
+	if (m_acc > m_slice) {
+		m_inLoop = true;
+	}
+	return m_inLoop;
+}
+
+bool GameTime::tick()
+{
+	if (m_acc > m_slice) {
+		m_acc -= m_slice;
+		return true;
+	}
+	return false;
+}
+
+void GameTime::reset()
+{
+	m_lastUpdate = m_current;
+	m_inLoop = false;
+}
+
+void GameTime::accumulateTime()
+{
+	updateTime();
+	
+	m_acc += (double) (m_current - m_lastUpdate);
+	if (m_acc > (1000.f / m_slice)) {
+		m_acc = 1000.f / m_slice;
+	}
+}
+
+void GameTime::updateTime()
+{
+	m_current = System::getMilliseconds();
+
+	// Just to be safe. check so we don't get a negative interval.
+	if (m_current < m_lastUpdate) {
+		m_lastUpdate = m_current;
+	}
+}