1 files changed, 55 insertions, 6 deletions

diff --git a/scene/resources/gradient.h b/scene/resources/gradient.h
index cf5b179c45..c2085b3a13 100644
--- a/scene/resources/gradient.h
+++ b/scene/resources/gradient.h
@@ -5,8 +5,8 @@
 /*                           GODOT ENGINE                                */
 /*                      https://godotengine.org                          */
 /*************************************************************************/
-/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
-/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
 /*                                                                       */
 /* Permission is hereby granted, free of charge, to any person obtaining */
 /* a copy of this software and associated documentation files (the       */
@@ -38,6 +38,12 @@ class Gradient : public Resource {
 	OBJ_SAVE_TYPE(Gradient);
 
 public:
+	enum InterpolationMode {
+		GRADIENT_INTERPOLATE_LINEAR,
+		GRADIENT_INTERPOLATE_CONSTANT,
+		GRADIENT_INTERPOLATE_CUBIC,
+	};
+
 	struct Point {
 		float offset = 0.0;
 		Color color;
@@ -49,6 +55,8 @@ public:
 private:
 	Vector<Point> points;
 	bool is_sorted = true;
+	InterpolationMode interpolation_mode = GRADIENT_INTERPOLATE_LINEAR;
+
 	_FORCE_INLINE_ void _update_sorting() {
 		if (!is_sorted) {
 			points.sort();
@@ -65,9 +73,9 @@ public:
 
 	void add_point(float p_offset, const Color &p_color);
 	void remove_point(int p_index);
-
 	void set_points(Vector<Point> &p_points);
 	Vector<Point> &get_points();
+	void reverse();
 
 	void set_offset(int pos, const float offset);
 	float get_offset(int pos);
@@ -81,6 +89,13 @@ public:
 	void set_colors(const Vector<Color> &p_colors);
 	Vector<Color> get_colors() const;
 
+	void set_interpolation_mode(InterpolationMode p_interp_mode);
+	InterpolationMode get_interpolation_mode();
+
+	_FORCE_INLINE_ float cubic_interpolate(float p0, float p1, float p2, float p3, float x) {
+		return p1 + 0.5 * x * (p2 - p0 + x * (2.0 * p0 - 5.0 * p1 + 4.0 * p2 - p3 + x * (3.0 * (p1 - p2) + p3 - p0)));
+	}
+
 	_FORCE_INLINE_ Color get_color_at_offset(float p_offset) {
 		if (points.is_empty()) {
 			return Color(0, 0, 0, 1);
@@ -88,7 +103,7 @@ public:
 
 		_update_sorting();
 
-		//binary search
+		// Binary search.
 		int low = 0;
 		int high = points.size() - 1;
 		int middle = 0;
@@ -111,7 +126,7 @@ public:
 			}
 		}
 
-		//return interpolated value
+		// Return interpolated value.
 		if (points[middle].offset > p_offset) {
 			middle--;
 		}
@@ -125,10 +140,44 @@ public:
 		}
 		const Point &pointFirst = points[first];
 		const Point &pointSecond = points[second];
-		return pointFirst.color.lerp(pointSecond.color, (p_offset - pointFirst.offset) / (pointSecond.offset - pointFirst.offset));
+
+		switch (interpolation_mode) {
+			case GRADIENT_INTERPOLATE_LINEAR: {
+				return pointFirst.color.lerp(pointSecond.color, (p_offset - pointFirst.offset) / (pointSecond.offset - pointFirst.offset));
+			} break;
+			case GRADIENT_INTERPOLATE_CONSTANT: {
+				return pointFirst.color;
+			} break;
+			case GRADIENT_INTERPOLATE_CUBIC: {
+				int p0 = first - 1;
+				int p3 = second + 1;
+				if (p3 >= points.size()) {
+					p3 = second;
+				}
+				if (p0 < 0) {
+					p0 = first;
+				}
+				const Point &pointP0 = points[p0];
+				const Point &pointP3 = points[p3];
+
+				float x = (p_offset - pointFirst.offset) / (pointSecond.offset - pointFirst.offset);
+				float r = cubic_interpolate(pointP0.color.r, pointFirst.color.r, pointSecond.color.r, pointP3.color.r, x);
+				float g = cubic_interpolate(pointP0.color.g, pointFirst.color.g, pointSecond.color.g, pointP3.color.g, x);
+				float b = cubic_interpolate(pointP0.color.b, pointFirst.color.b, pointSecond.color.b, pointP3.color.b, x);
+				float a = cubic_interpolate(pointP0.color.a, pointFirst.color.a, pointSecond.color.a, pointP3.color.a, x);
+
+				return Color(r, g, b, a);
+			} break;
+			default: {
+				// Fallback to linear interpolation.
+				return pointFirst.color.lerp(pointSecond.color, (p_offset - pointFirst.offset) / (pointSecond.offset - pointFirst.offset));
+			}
+		}
 	}
 
 	int get_points_count() const;
 };
 
+VARIANT_ENUM_CAST(Gradient::InterpolationMode);
+
 #endif // GRADIENT_H