Add API for HSL conversion

Math ported pretty much 1:1 from https://en.wikipedia.org/wiki/HSL_and_HSV
Style doesn't match the existing HSV code exactly, but should be close enough.

5 files changed, 102 insertions, 0 deletions

diff --git a/core/math/color.cpp b/core/math/color.cpp
index 0d9325f236..f4b8903157 100644
--- a/core/math/color.cpp
+++ b/core/math/color.cpp
@@ -188,6 +188,32 @@ float Color::get_v() const {
 	return max;
 }
 
+float Color::get_hsl_h() const {
+	return get_h();
+}
+
+float Color::get_hsl_s() const {
+	float min = MIN(MIN(r, g), b);
+	float max = MAX(MAX(r, g), b);
+
+	float mid = (min + max) / 2.0f;
+
+	if (mid == 0.0f || mid == 1.0f) {
+		return 0.0f;
+	}
+
+	float delta = max - min;
+
+	return delta / (1.0f - Math::abs(2.0f * mid - 1.0f));
+}
+
+float Color::get_hsl_l() const {
+	float min = MIN(MIN(r, g), b);
+	float max = MAX(MAX(r, g), b);
+
+	return (min + max) / 2.0f;
+}
+
 void Color::set_hsv(float p_h, float p_s, float p_v, float p_alpha) {
 	int i;
 	float f, p, q, t;
@@ -242,6 +268,59 @@ void Color::set_hsv(float p_h, float p_s, float p_v, float p_alpha) {
 	}
 }
 
+void Color::set_hsl(float p_h, float p_s, float p_l, float p_alpha) {
+	a = p_alpha;
+
+	if (p_s == 0.0f) {
+		// Achromatic (gray)
+		r = g = b = p_l;
+		return;
+	}
+
+	p_h *= 6.0f;
+	p_h = Math::fmod(p_h, 6.0f);
+
+	float c = (1.0f - Math::abs(2.0f * p_l - 1.0f)) * p_s;
+	float x = c * (1.0f - Math::abs(Math::fmod(p_h, 2.0f) - 1.0f));
+	float m = p_l - c / 2.0f;
+
+	c += m;
+	x += m;
+
+	switch ((int)p_h) {
+		case 0: // Red is the dominant color
+			r = c;
+			g = x;
+			b = m;
+			break;
+		case 1: // Green is the dominant color
+			r = x;
+			g = c;
+			b = m;
+			break;
+		case 2:
+			r = m;
+			g = c;
+			b = x;
+			break;
+		case 3: // Blue is the dominant color
+			r = m;
+			g = x;
+			b = c;
+			break;
+		case 4:
+			r = x;
+			g = m;
+			b = c;
+			break;
+		default: // (5) Red is the dominant color
+			r = c;
+			g = m;
+			b = x;
+			break;
+	}
+}
+
 void Color::set_ok_hsl(float p_h, float p_s, float p_l, float p_alpha) {
 	ok_color::HSL hsl;
 	hsl.h = p_h;
@@ -468,6 +547,12 @@ Color Color::from_hsv(float p_h, float p_s, float p_v, float p_alpha) {
 	return c;
 }
 
+Color Color::from_hsl(float p_h, float p_s, float p_l, float p_alpha) {
+	Color c;
+	c.set_hsl(p_h, p_s, p_l, p_alpha);
+	return c;
+}
+
 Color Color::from_rgbe9995(uint32_t p_rgbe) {
 	float r = p_rgbe & 0x1ff;
 	float g = (p_rgbe >> 9) & 0x1ff;
diff --git a/core/math/color.h b/core/math/color.h
index 65d7377c1c..4a056335c1 100644
--- a/core/math/color.h
+++ b/core/math/color.h
@@ -57,6 +57,10 @@ struct _NO_DISCARD_ Color {
 	float get_s() const;
 	float get_v() const;
 	void set_hsv(float p_h, float p_s, float p_v, float p_alpha = 1.0f);
+	float get_hsl_h() const;
+	float get_hsl_s() const;
+	float get_hsl_l() const;
+	void set_hsl(float p_h, float p_s, float p_l, float p_alpha = 1.0f);
 	float get_ok_hsl_h() const;
 	float get_ok_hsl_s() const;
 	float get_ok_hsl_l() const;
@@ -198,6 +202,7 @@ struct _NO_DISCARD_ Color {
 	static Color get_named_color(int p_idx);
 	static Color from_string(const String &p_string, const Color &p_default);
 	static Color from_hsv(float p_h, float p_s, float p_v, float p_alpha = 1.0f);
+	static Color from_hsl(float p_h, float p_s, float p_l, float p_alpha = 1.0f);
 	static Color from_ok_hsl(float p_h, float p_s, float p_l, float p_alpha = 1.0f);
 	static Color from_rgbe9995(uint32_t p_rgbe);
 
@@ -217,6 +222,9 @@ struct _NO_DISCARD_ Color {
 	_FORCE_INLINE_ void set_h(float p_h) { set_hsv(p_h, get_s(), get_v(), a); }
 	_FORCE_INLINE_ void set_s(float p_s) { set_hsv(get_h(), p_s, get_v(), a); }
 	_FORCE_INLINE_ void set_v(float p_v) { set_hsv(get_h(), get_s(), p_v, a); }
+	_FORCE_INLINE_ void set_hsl_h(float p_h) { set_hsl(p_h, get_hsl_s(), get_hsl_l(), a); }
+	_FORCE_INLINE_ void set_hsl_s(float p_s) { set_hsl(get_hsl_h(), p_s, get_hsl_l(), a); }
+	_FORCE_INLINE_ void set_hsl_l(float p_l) { set_hsl(get_hsl_h(), get_hsl_s(), p_l, a); }
 	_FORCE_INLINE_ void set_ok_hsl_h(float p_h) { set_ok_hsl(p_h, get_ok_hsl_s(), get_ok_hsl_l(), a); }
 	_FORCE_INLINE_ void set_ok_hsl_s(float p_s) { set_ok_hsl(get_ok_hsl_h(), p_s, get_ok_hsl_l(), a); }
 	_FORCE_INLINE_ void set_ok_hsl_l(float p_l) { set_ok_hsl(get_ok_hsl_h(), get_ok_hsl_s(), p_l, a); }
diff --git a/core/variant/variant_call.cpp b/core/variant/variant_call.cpp
index e83b6dc183..185e30311b 100644
--- a/core/variant/variant_call.cpp
+++ b/core/variant/variant_call.cpp
@@ -2000,6 +2000,7 @@ static void _register_variant_builtin_methods() {
 	bind_static_method(Color, html_is_valid, sarray("color"), varray());
 	bind_static_method(Color, from_string, sarray("str", "default"), varray());
 	bind_static_method(Color, from_hsv, sarray("h", "s", "v", "alpha"), varray(1.0));
+	bind_static_method(Color, from_hsl, sarray("h", "s", "l", "alpha"), varray(1.0));
 	bind_static_method(Color, from_ok_hsl, sarray("h", "s", "l", "alpha"), varray(1.0));
 
 	bind_static_method(Color, from_rgbe9995, sarray("rgbe"), varray());
diff --git a/core/variant/variant_setget.cpp b/core/variant/variant_setget.cpp
index 30fb5d0e9f..ce035f5f7a 100644
--- a/core/variant/variant_setget.cpp
+++ b/core/variant/variant_setget.cpp
@@ -139,6 +139,10 @@ void register_named_setters_getters() {
 	REGISTER_MEMBER(Color, h);
 	REGISTER_MEMBER(Color, s);
 	REGISTER_MEMBER(Color, v);
+
+	REGISTER_MEMBER(Color, hsl_h);
+	REGISTER_MEMBER(Color, hsl_s);
+	REGISTER_MEMBER(Color, hsl_l);
 }
 
 void unregister_named_setters_getters() {
diff --git a/core/variant/variant_setget.h b/core/variant/variant_setget.h
index 176967344f..db6e273817 100644
--- a/core/variant/variant_setget.h
+++ b/core/variant/variant_setget.h
@@ -344,6 +344,10 @@ SETGET_NUMBER_STRUCT_FUNC(Color, double, h, set_h, get_h)
 SETGET_NUMBER_STRUCT_FUNC(Color, double, s, set_s, get_s)
 SETGET_NUMBER_STRUCT_FUNC(Color, double, v, set_v, get_v)
 
+SETGET_NUMBER_STRUCT_FUNC(Color, double, hsl_h, set_hsl_h, get_hsl_h)
+SETGET_NUMBER_STRUCT_FUNC(Color, double, hsl_s, set_hsl_s, get_hsl_s)
+SETGET_NUMBER_STRUCT_FUNC(Color, double, hsl_l, set_hsl_l, get_hsl_l)
+
 SETGET_NUMBER_STRUCT_FUNC(Color, double, ok_hsl_h, set_ok_hsl_h, get_ok_hsl_h)
 SETGET_NUMBER_STRUCT_FUNC(Color, double, ok_hsl_s, set_ok_hsl_s, get_ok_hsl_s)
 SETGET_NUMBER_STRUCT_FUNC(Color, double, ok_hsl_l, set_ok_hsl_l, get_ok_hsl_l)