update bullet so it actually works

Moved the addSourceDirectory for physics/Bullet into the Engine/Source/CMakeLists.txt file that way it can actually appear where we expect it to in the solution explorer.

Engine/lib/bullet/examples/TinyAudio/b3ADSR.cpp

@@ -0,0 +1,109 @@
+#include "b3ADSR.h"
+//ADSR mostly copied/reimplemented from Stk, see
+//http://github.com/thestk/stk
+
+//! ADSR envelope states.
+
+enum
+{
+	ADSR_ATTACK,  /*!< Attack */
+	ADSR_DECAY,   /*!< Decay */
+	ADSR_SUSTAIN, /*!< Sustain */
+	ADSR_RELEASE, /*!< Release */
+	ADSR_IDLE     /*!< Before attack / after release */
+};
+
+b3ADSR::b3ADSR()
+{
+	m_target = 0.0;
+	m_value = 0.0;
+	m_attackRate = 0.001;
+	m_decayRate = 0.00001;
+	m_releaseRate = 0.0005;
+	m_sustainLevel = 0.5;
+	m_state = ADSR_IDLE;
+	m_autoKeyOff = false;
+}
+
+b3ADSR::~b3ADSR()
+{
+}
+
+double b3ADSR::tick()
+{
+	switch (m_state)
+	{
+		case ADSR_ATTACK:
+			m_value += m_attackRate;
+			if (m_value >= m_target)
+			{
+				m_value = m_target;
+				m_target = m_sustainLevel;
+				m_state = ADSR_DECAY;
+			}
+			break;
+
+		case ADSR_DECAY:
+			if (m_value > m_sustainLevel)
+			{
+				m_value -= m_decayRate;
+				if (m_value <= m_sustainLevel)
+				{
+					m_value = m_sustainLevel;
+					m_state = ADSR_SUSTAIN;
+					if (m_autoKeyOff)
+					{
+						keyOff();
+					}
+				}
+			}
+			else
+			{
+				m_value += m_decayRate;  // attack target < sustain level
+				if (m_value >= m_sustainLevel)
+				{
+					m_value = m_sustainLevel;
+					m_state = ADSR_SUSTAIN;
+					if (m_autoKeyOff)
+					{
+						keyOff();
+					}
+				}
+			}
+			break;
+
+		case ADSR_RELEASE:
+			m_value -= m_releaseRate;
+			if (m_value <= 0.0)
+			{
+				m_value = 0.0;
+				m_state = ADSR_IDLE;
+			}
+	}
+
+	return m_value;
+}
+
+bool b3ADSR::isIdle() const
+{
+	return m_state == ADSR_IDLE;
+}
+
+void b3ADSR::keyOn(bool autoKeyOff)
+{
+	m_autoKeyOff = autoKeyOff;
+	if (m_target <= 0.0)
+		m_target = 1.0;
+	if (m_attackRate == 1)
+	{
+		m_value = 1.0;
+	}
+	m_state = ADSR_ATTACK;
+}
+
+void b3ADSR::keyOff()
+{
+	m_autoKeyOff = false;
+	m_target = 0.0;
+	m_state = ADSR_RELEASE;
+}