From 7361457ed17670b37279f12fe334e7a9ce7ea34e Mon Sep 17 00:00:00 2001
From: Jacob Palecki <JacobPalecki@gmail.com>
Date: Thu, 16 Sep 2021 01:29:51 -0700
Subject: Get power cap working

---
 common/accel-power.hpp                     | 122 +++++++++++++++++++++++++++--
 grapher/Models/Options/AccelTypeOptions.cs |   2 +-
 2 files changed, 115 insertions(+), 9 deletions(-)

diff --git a/common/accel-power.hpp b/common/accel-power.hpp
index b3e16fb..0b9353d 100644
--- a/common/accel-power.hpp
+++ b/common/accel-power.hpp
@@ -7,10 +7,10 @@
 namespace rawaccel {
 
 	struct power_base {
-		static double base_fn(double x, const accel_args& args)
+		static double base_fn(double x, double scale, const accel_args& args)
 		{
 			// f(x) = w(mx)^k
-			return args.weight * pow(args.scale * x, args.exponent_power);
+			return args.weight * pow(scale * x, args.exponent_power);
 		}
 	};
 
@@ -18,51 +18,157 @@ namespace rawaccel {
 
 	template <>
 	struct power<LEGACY> : power_base {
-		vec2d cap = { DBL_MAX, DBL_MAX };
+		double cap = DBL_MAX;
+		double scale = 0;
 
 		power(const accel_args& args)
 		{
+			// Note that cap types may overwrite this below. 
+			scale = args.scale;
+
+			switch (args.cap_mode){
+			case classic_cap_mode::in:
+				if (args.cap.x > 0)
+				{
+					cap = base_fn(
+							args.cap.x,
+							args.scale,
+							args);
+				}
+				break;
+			case classic_cap_mode::io:
+				if (args.cap.x > 0 &&
+					args.cap.y > 1)
+				{
+					cap = args.cap.y;
+					scale = scale_from_sens_point(
+								args.cap.y,
+								args.cap.x,
+								args.exponent_power);
+				}
+				break;
+			case classic_cap_mode::out:
+			default:
+				if (args.cap.y > 1)
+				{
+					cap = args.cap.y;
+				}
+				break;
+			}
+			/*
 			if (args.cap.x > 0) {
 				cap.x = args.cap.x;
 				cap.y = base_fn(cap.x, args);
 			}
+			*/
 		}
 
 		double operator()(double speed, const accel_args& args) const
 		{
-			if (speed < cap.x) {
-				return base_fn(speed, args);
-			}
-			return cap.y;
+            return minsd(base_fn(speed, scale, args), cap);
 		}
 
+		double static scale_from_sens_point(double sens, double input, double power)
+		{
+			return pow(sens, 1 / power) / input;
+		}
 	};
 
 	template <>
 	struct power<GAIN> : power_base {
 		vec2d cap = { DBL_MAX, DBL_MAX };
 		double constant = 0;
+		double scale = 0;
 
 		power(const accel_args& args) 
 		{
+			/*
 			if (args.cap.x > 0) {
 				cap.x = args.cap.x;
 				double output = base_fn(cap.x, args);
 				cap.y = output * (args.exponent_power + 1);
 				constant = -args.exponent_power * output * args.cap.x;
 			}
+			*/
+
+			// Note that cap types may overwrite this below. 
+			scale = args.scale;
+
+			switch (args.cap_mode) {
+			case classic_cap_mode::in:
+				if (args.cap.x > 0) {
+					cap.x = args.cap.x;
+					cap.y = gain(
+								args.cap.x,
+								args.exponent_power,
+								scale);
+
+					constant = integration_constant(
+								cap.x,
+								cap.y,
+								base_fn(cap.x, scale, args));
+				}
+			case classic_cap_mode::io:
+				if (args.cap.x > 0 &&
+					args.cap.y > 1) {
+					cap.x = args.cap.x;
+					cap.y = args.cap.y;
+					scale = scale_from_gain_point(
+						args.cap.x,
+						args.cap.y,
+						args.exponent_power);
+
+					constant = integration_constant(
+								cap.x,
+								cap.y,
+								base_fn(cap.x, scale, args));
+				}
+			case classic_cap_mode::out:
+			default:
+				if (args.cap.y > 1) {
+					cap.y = args.cap.y;
+					cap.x = gain_inverse(
+								args.cap.y,
+								args.exponent_power,
+								scale);
+
+					constant = integration_constant(
+								cap.x,
+								cap.y,
+								base_fn(cap.x, scale, args));
+				}
+				break;
+			}
 		}
 
 		double operator()(double speed, const accel_args& args) const
 		{
 			if (speed < cap.x) {
-				return base_fn(speed, args);
+				return base_fn(speed, scale, args);
 			}
 			else {
 				return cap.y + constant / speed;
 			}
 		}
 
+		double static gain_inverse(double gain, double power, double scale)
+		{
+			return pow(gain / (power + 1), 1 / power) / scale;
+		}
+		double static gain(double input, double power, double scale)
+		{
+			return (power + 1) * pow(input * scale, power);
+		}
+
+		double static scale_from_gain_point(double input, double gain, double power)
+		{
+			return pow(gain / (power + 1), 1 / power) / input;
+		}
+
+		double static integration_constant(double input, double gain, double output)
+		{
+			return (output - gain) * input;
+		}
 	};
 
 }
diff --git a/grapher/Models/Options/AccelTypeOptions.cs b/grapher/Models/Options/AccelTypeOptions.cs
index 3d2f840..b7a7b7b 100644
--- a/grapher/Models/Options/AccelTypeOptions.cs
+++ b/grapher/Models/Options/AccelTypeOptions.cs
@@ -323,7 +323,7 @@ namespace grapher
             }
             if (PowerCap.Visible)
             {
-                args.scale = ClassicCap.Slope.Field.Data;
+                args.scale = PowerCap.Slope.Field.Data;
                 args.cap.x = PowerCap.In.Field.Data;
                 args.cap.y = PowerCap.Out.Field.Data;
                 args.capMode = PowerCap.CapTypeOptions.GetSelectedCapMode();
-- 
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