Reimplement basic waveforms using a complex oscillator

libs/audio/include/psemek/audio/oscillator.hpp

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <psemek/audio/constants.hpp>
+#include <psemek/geom/constants.hpp>
+
+#include <complex>
+
+namespace psemek::audio
+{
+
+	struct oscillator
+	{
+		oscillator(float frequency)
+			: m_(std::exp(std::complex<float>{0.f, 2.f * geom::pi * frequency * inv_frequency}))
+		{}
+
+		std::complex<float> phase() const
+		{
+			return phase_;
+		}
+
+		std::complex<float> next()
+		{
+			phase_ *= m_;
+			phase_ /= std::abs(phase_);
+			return phase_;
+		}
+
+	private:
+		std::complex<float> phase_{1.f, 0.f};
+		std::complex<float> m_;
+	};
+
+}

libs/audio/include/psemek/audio/wave/generator.hpp

@@ -12,7 +12,6 @@ namespace psemek::audio
 	{
 		generator_stream(Func func)
 			: func_(std::move(func))
-			, phase_(0.f)
 		{}
 
 		std::size_t read(float * data, std::size_t sample_count) override
@@ -20,17 +19,15 @@ namespace psemek::audio
 			auto end = data + sample_count;
 			for (auto p = data; p != end;)
 			{
-				float v = func_(phase_);
+				float v = func_();
 				*p++ = v;
 				*p++ = v;
-				phase_ += inv_frequency;
 			}
 			return sample_count;
 		}
 
 	private:
 		Func func_;
-		float phase_;
 	};
 
 }

libs/audio/source/wave/sawtooth.cpp

@@ -1,7 +1,8 @@
 #include <psemek/audio/wave/sawtooth.hpp>
 #include <psemek/audio/wave/generator.hpp>
-#include <psemek/geom/math.hpp>
+#include <psemek/audio/oscillator.hpp>
 #include <psemek/util/to_shared.hpp>
+#include <psemek/log/log.hpp>
 
 #include <cmath>
 
@@ -10,9 +11,9 @@ namespace psemek::audio
 
 	stream_ptr sawtooth_wave(float frequency)
 	{
-		auto func = [frequency](float t){
+		auto func = [o = oscillator{frequency}]() mutable {
-			t *= frequency;
+			auto z = o.next();
-			return (t - std::floor(t)) * 2.f - 1.f;
+			return (2.f / geom::pi) * (- std::atan2(z.real() + 1.f, z.imag()));
 		};
 
 		return util::to_shared(generator_stream(func));

libs/audio/source/wave/sine.cpp

@@ -1,19 +1,18 @@
 #include <psemek/audio/wave/sine.hpp>
 #include <psemek/audio/wave/generator.hpp>
-#include <psemek/geom/math.hpp>
+#include <psemek/audio/oscillator.hpp>
 #include <psemek/util/to_shared.hpp>
 
 #include <cmath>
+#include <complex>
 
 namespace psemek::audio
 {
 
 	stream_ptr sine_wave(float frequency)
 	{
-		float angular_frequency = frequency * 2.f * geom::pi;
+		auto func = [o = oscillator{frequency}]() mutable {
-
+			return o.next().imag();
-		auto func = [angular_frequency](float t){
-			return std::sin(angular_frequency * t);
 		};
 
 		return util::to_shared(generator_stream(func));

libs/audio/source/wave/square.cpp

@@ -1,6 +1,6 @@
 #include <psemek/audio/wave/square.hpp>
 #include <psemek/audio/wave/generator.hpp>
-#include <psemek/geom/math.hpp>
+#include <psemek/audio/oscillator.hpp>
 #include <psemek/util/to_shared.hpp>
 
 #include <cmath>
@@ -10,9 +10,8 @@ namespace psemek::audio
 
 	stream_ptr square_wave(float frequency)
 	{
-		auto func = [frequency](float t){
+		auto func = [o = oscillator{frequency}]() mutable {
-			t *= frequency;
+			return o.next().imag() > 0.f ? 1.f : -1.f;
-			return (t - std::floor(t)) < 0.5f ? 1.f : -1.f;
 		};
 
 		return util::to_shared(generator_stream(func));

libs/audio/source/wave/triangle.cpp

@@ -1,6 +1,6 @@
 #include <psemek/audio/wave/triangle.hpp>
 #include <psemek/audio/wave/generator.hpp>
-#include <psemek/geom/math.hpp>
+#include <psemek/audio/oscillator.hpp>
 #include <psemek/util/to_shared.hpp>
 
 #include <cmath>
@@ -10,8 +10,9 @@ namespace psemek::audio
 
 	stream_ptr triangle_wave(float frequency)
 	{
-		auto func = [frequency](float t){
+		auto func = [o = oscillator{frequency}]() mutable {
-			t *= frequency;
+			auto const z = o.next();
+			float const t = 0.5f * std::atan2(z.imag(), z.real()) / (geom::pi) + 0.5f;
 			return 4.f * std::abs(t - std::floor(t + 0.5f)) - 1.f;
 		};