Sigmoid gain

4 files changed, 41 insertions, 2 deletions

diff --git a/common/accel-sigmoid.hpp b/common/accel-sigmoid.hpp
index 5bbe58f..dc2066d 100644
--- a/common/accel-sigmoid.hpp
+++ b/common/accel-sigmoid.hpp
@@ -19,7 +19,7 @@ namespace rawaccel {
 		}
 
 		inline double accelerate(double speed) const {
-			//f(x) = k/(1+e^(-m(c-x)))
+			//f(x) = k/(1+e^(-m(x-c)))
 			return limit / (exp(-speed_coeff * (speed - midpoint)) + 1);
 		}
 
diff --git a/common/accel-sigmoidgain.hpp b/common/accel-sigmoidgain.hpp
new file mode 100644
index 0000000..0a2e54d
--- /dev/null
+++ b/common/accel-sigmoidgain.hpp
@@ -0,0 +1,37 @@
+#pragma once
+
+#include <math.h>
+
+#include "accel-base.hpp"
+
+namespace rawaccel {
+
+	/// <summary> Struct to hold sigmoid (s-shaped) gain implementation. </summary>
+	struct accel_sigmoidgain : accel_base {
+		double limit = 1;
+		double midpoint = 0;
+		double additive_constant = 0;
+		double integration_constant = 0;
+
+		accel_sigmoidgain(const accel_args& args) : accel_base(args) {
+			verify(args);
+
+			limit = args.limit - 1;
+			midpoint = args.midpoint;
+			additive_constant = exp(speed_coeff*midpoint);
+			integration_constant = log(1 + additive_constant);
+		}
+
+		inline double accelerate(double speed) const {
+			//f(x) = k/(1+e^(-m(c-x)))
+			double scaled_speed = speed_coeff * speed;
+			return limit * ((log(additive_constant+exp(scaled_speed)) - integration_constant)/scaled_speed);
+		}
+
+		void verify(const accel_args& args) const {
+			if (args.limit <= 1) bad_arg("exponent must be greater than 1");
+			if (args.midpoint < 0) bad_arg("midpoint must not be negative");
+		}
+	};
+
+}
diff --git a/common/common.vcxitems b/common/common.vcxitems
index 0471b5f..2e9265c 100644
--- a/common/common.vcxitems
+++ b/common/common.vcxitems
@@ -23,6 +23,7 @@
     <ClInclude Include="$(MSBuildThisFileDirectory)accel-noaccel.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)accel-power.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)accel-sigmoid.hpp" />
+    <ClInclude Include="$(MSBuildThisFileDirectory)accel-sigmoidgain.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)rawaccel-error.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)rawaccel-io.hpp" />
     <ClInclude Include="$(MSBuildThisFileDirectory)rawaccel.hpp" />
diff --git a/common/rawaccel.hpp b/common/rawaccel.hpp
index 37418cd..7e72f20 100644
--- a/common/rawaccel.hpp
+++ b/common/rawaccel.hpp
@@ -12,6 +12,7 @@
 #include "accel-naturalgain.hpp"
 #include "accel-logarithmic.hpp"
 #include "accel-sigmoid.hpp"
+#include "accel-sigmoidgain.hpp"
 #include "accel-power.hpp"
 #include "accel-noaccel.hpp"
 
@@ -77,7 +78,7 @@ namespace rawaccel {
     };
 
     /// <summary> Tagged union to hold all accel implementations and allow "polymorphism" via a visitor call. </summary>
-    using accel_impl_t = tagged_union<accel_linear, accel_classic, accel_natural, accel_logarithmic, accel_sigmoid, accel_power, accel_naturalgain, accel_noaccel>;
+    using accel_impl_t = tagged_union<accel_linear, accel_classic, accel_natural, accel_logarithmic, accel_sigmoid, accel_power, accel_naturalgain, accel_sigmoidgain, accel_noaccel>;
 
     /// <summary> Struct to hold information about applying a gain cap. </summary>
     struct velocity_gain_cap {