From d954f0aced72e86a2f1179a492f79df6b5c72103 Mon Sep 17 00:00:00 2001
From: Steve Lascos <steve@blackaddr.com>
Date: Sat, 26 Jan 2019 16:07:32 -0500
Subject: [PATCH] LFO: square and triangle wave now working

---
 src/LibBasicFunctions.h               |  3 ++
 src/common/LowFrequencyOscillator.cpp | 42 ++++++++++++---------------
 2 files changed, 21 insertions(+), 24 deletions(-)

diff --git a/src/LibBasicFunctions.h b/src/LibBasicFunctions.h
index a75a164..7a7469e 100644
--- a/src/LibBasicFunctions.h
+++ b/src/LibBasicFunctions.h
@@ -476,6 +476,9 @@ private:
 	const T PI_F = 3.14159265358979323846264338327950288419716939937510582097494459230781640628620899; ///< 2*PI
 	const T TWO_PI_F = 2.0 *  3.14159265358979323846264338327950288419716939937510582097494459230781640628620899; ///< 2*PI
 	const T PI_DIV2_F = 0.5 *  3.14159265358979323846264338327950288419716939937510582097494459230781640628620899; ///< PI/2
+	const T THREE_PI_DIV2_F = 1.5 *  3.14159265358979323846264338327950288419716939937510582097494459230781640628620899; ///< 3*PI/2
+    const float TRIANGE_POS_SLOPE = 2.0f/PI_F;
+    const float TRIANGE_NEG_SLOPE = -2.0f/PI_F;
 };
 
 } // BALibrary
diff --git a/src/common/LowFrequencyOscillator.cpp b/src/common/LowFrequencyOscillator.cpp
index 44924f3..d293816 100644
--- a/src/common/LowFrequencyOscillator.cpp
+++ b/src/common/LowFrequencyOscillator.cpp
@@ -101,33 +101,27 @@ T *LowFrequencyOscillatorVector<T>::getNextVector()
 		break;
 	case Waveform::SQUARE :
 		for (auto i=0; i<AUDIO_BLOCK_SAMPLES; i++) {
-			if (m_phaseVec[i] > 3*PI_F) {
-				m_outputVec[i] = 0.0f;
-			}
-			else if (m_phaseVec[i] > 2*PI_F) {
-				m_outputVec[i] = 1.0f;
-			}
-			else if (m_phaseVec[i] > PI_F) {
-				m_outputVec[i] = 0.0f;
-			} else {
-				m_outputVec[i] = 1.0f;
-			}
+
+		    if (m_phaseVec[i] < PI_F) {
+		        m_outputVec[i] = -1.0f;
+		    } else {
+		        m_outputVec[i] = 1.0f;
+		    }
 		}
 		break;
 	case Waveform::TRIANGLE :
-//		for (auto i=0; i<AUDIO_BLOCK_SAMPLES; i++) {
-//			if (m_phaseVec[i] > 3*PI_F) {
-//				m_outputVec[i] = ;
-//			}
-//			else if (m_phaseVec[i] > 2*PI_F) {
-//				m_outputVec[i] = 1.0f;
-//			}
-//			else if (m_phaseVec[i] > PI_F) {
-//				m_outputVec[i] = 0.0f;
-//			} else {
-//				m_outputVec[i] = 1.0f;
-//			}
-//		}
+	    // A triangle is made up from two different line equations of form y=mx+b
+	    // where m = +2/pi or -2/pi. A "Triangle Cos" starts at +1.0 and moves to
+	    // -1.0 from angles 0 to PI radians.
+		for (auto i=0; i<AUDIO_BLOCK_SAMPLES; i++) {
+            if (m_phaseVec[i] < PI_F) {
+                // y = (-2/pi)*x + 1.0
+                m_outputVec[i] = TRIANGE_NEG_SLOPE * m_phaseVec[i] + 1.0f;
+            } else {
+                // y = (2/pi)*x -1.0
+                m_outputVec[i] = TRIANGE_POS_SLOPE * (m_phaseVec[i]-PI_F) - 1.0f;
+            }
+		}
 		break;
 	case Waveform::RANDOM :
 		break;