From d28da86f9ff5a70284e4a2078fa08867d4858a57 Mon Sep 17 00:00:00 2001
From: Poommetee Ketson <poommetee@protonmail.com>
Date: Thu, 10 Aug 2017 21:06:10 +0700
Subject: [PATCH] GDScript Built-in: add inverse_lerp & range_lerp

---
 core/math/math_funcs.h            | 10 ++++++++--
 modules/gdscript/gd_functions.cpp | 30 ++++++++++++++++++++++++++++++
 modules/gdscript/gd_functions.h   |  2 ++
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/core/math/math_funcs.h b/core/math/math_funcs.h
index 45509a08082..2ce9a886220 100644
--- a/core/math/math_funcs.h
+++ b/core/math/math_funcs.h
@@ -153,8 +153,14 @@ public:
 	static _ALWAYS_INLINE_ double rad2deg(double p_y) { return p_y * 180.0 / Math_PI; }
 	static _ALWAYS_INLINE_ float rad2deg(float p_y) { return p_y * 180.0 / Math_PI; }
 
-	static _ALWAYS_INLINE_ double lerp(double a, double b, double c) { return a + (b - a) * c; }
-	static _ALWAYS_INLINE_ float lerp(float a, float b, float c) { return a + (b - a) * c; }
+	static _ALWAYS_INLINE_ double lerp(double p_from, double p_to, double p_weight) { return p_from + (p_to - p_from) * p_weight; }
+	static _ALWAYS_INLINE_ float lerp(float p_from, float p_to, float p_weight) { return p_from + (p_to - p_from) * p_weight; }
+
+	static _ALWAYS_INLINE_ double inverse_lerp(double p_from, double p_to, double p_value) { return (p_value - p_from) / (p_to - p_from); }
+	static _ALWAYS_INLINE_ float inverse_lerp(float p_from, float p_to, float p_value) { return (p_value - p_from) / (p_to - p_from); }
+
+	static _ALWAYS_INLINE_ double range_lerp(double p_value, double p_istart, double p_istop, double p_ostart, double p_ostop) { return Math::lerp(p_ostart, p_ostop, Math::inverse_lerp(p_istart, p_istop, p_value)); }
+	static _ALWAYS_INLINE_ float range_lerp(float p_value, float p_istart, float p_istop, float p_ostart, float p_ostop) { return Math::lerp(p_ostart, p_ostop, Math::inverse_lerp(p_istart, p_istop, p_value)); }
 
 	static _ALWAYS_INLINE_ double linear2db(double p_linear) { return Math::log(p_linear) * 8.6858896380650365530225783783321; }
 	static _ALWAYS_INLINE_ float linear2db(float p_linear) { return Math::log(p_linear) * 8.6858896380650365530225783783321; }
diff --git a/modules/gdscript/gd_functions.cpp b/modules/gdscript/gd_functions.cpp
index 209bdadd675..e0681382e0d 100644
--- a/modules/gdscript/gd_functions.cpp
+++ b/modules/gdscript/gd_functions.cpp
@@ -70,6 +70,8 @@ const char *GDFunctions::get_func_name(Function p_func) {
 		"decimals",
 		"stepify",
 		"lerp",
+		"inverse_lerp",
+		"range_lerp",
 		"dectime",
 		"randomize",
 		"randi",
@@ -326,6 +328,22 @@ void GDFunctions::call(Function p_func, const Variant **p_args, int p_arg_count,
 			VALIDATE_ARG_NUM(2);
 			r_ret = Math::lerp((double)*p_args[0], (double)*p_args[1], (double)*p_args[2]);
 		} break;
+		case MATH_INVERSE_LERP: {
+			VALIDATE_ARG_COUNT(3);
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			VALIDATE_ARG_NUM(2);
+			r_ret = Math::inverse_lerp((double)*p_args[0], (double)*p_args[1], (double)*p_args[2]);
+		} break;
+		case MATH_RANGE_LERP: {
+			VALIDATE_ARG_COUNT(5);
+			VALIDATE_ARG_NUM(0);
+			VALIDATE_ARG_NUM(1);
+			VALIDATE_ARG_NUM(2);
+			VALIDATE_ARG_NUM(3);
+			VALIDATE_ARG_NUM(4);
+			r_ret = Math::range_lerp((double)*p_args[0], (double)*p_args[1], (double)*p_args[2], (double)*p_args[3], (double)*p_args[4]);
+		} break;
 		case MATH_DECTIME: {
 			VALIDATE_ARG_COUNT(3);
 			VALIDATE_ARG_NUM(0);
@@ -1252,6 +1270,8 @@ bool GDFunctions::is_deterministic(Function p_func) {
 		case MATH_DECIMALS:
 		case MATH_STEPIFY:
 		case MATH_LERP:
+		case MATH_INVERSE_LERP:
+		case MATH_RANGE_LERP:
 		case MATH_DECTIME:
 		case MATH_DEG2RAD:
 		case MATH_RAD2DEG:
@@ -1420,6 +1440,16 @@ MethodInfo GDFunctions::get_info(Function p_func) {
 			mi.return_val.type = Variant::REAL;
 			return mi;
 		} break;
+		case MATH_INVERSE_LERP: {
+			MethodInfo mi("inverse_lerp", PropertyInfo(Variant::REAL, "from"), PropertyInfo(Variant::REAL, "to"), PropertyInfo(Variant::REAL, "value"));
+			mi.return_val.type = Variant::REAL;
+			return mi;
+		} break;
+		case MATH_RANGE_LERP: {
+			MethodInfo mi("range_lerp", PropertyInfo(Variant::REAL, "value"), PropertyInfo(Variant::REAL, "istart"), PropertyInfo(Variant::REAL, "istop"), PropertyInfo(Variant::REAL, "ostart"), PropertyInfo(Variant::REAL, "ostop"));
+			mi.return_val.type = Variant::REAL;
+			return mi;
+		} break;
 		case MATH_DECTIME: {
 			MethodInfo mi("dectime", PropertyInfo(Variant::REAL, "value"), PropertyInfo(Variant::REAL, "amount"), PropertyInfo(Variant::REAL, "step"));
 			mi.return_val.type = Variant::REAL;
diff --git a/modules/gdscript/gd_functions.h b/modules/gdscript/gd_functions.h
index 93cb5241182..11dfbd473c2 100644
--- a/modules/gdscript/gd_functions.h
+++ b/modules/gdscript/gd_functions.h
@@ -62,6 +62,8 @@ public:
 		MATH_DECIMALS,
 		MATH_STEPIFY,
 		MATH_LERP,
+		MATH_INVERSE_LERP,
+		MATH_RANGE_LERP,
 		MATH_DECTIME,
 		MATH_RANDOMIZE,
 		MATH_RAND,