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engines/twp/easing.h

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef TWP_EASING_H
+#define TWP_EASING_H
+
+#include "common/func.h"
+#include "math/vector2d.h"
+#include "twp/rectf.h"
+
+namespace Twp {
+
+typedef float EasingFunc(float t);
+
+typedef struct EasingFunc_t {
+	EasingFunc *func;
+} EasingFunc_t;
+
+enum InterpolationKind {
+	IK_LINEAR = 0,
+	IK_EASEIN = 1,
+	IK_EASEINOUT = 2,
+	IK_EASEOUT = 3,
+	IK_SLOWEASEIN = 4,
+	IK_SLOWEASEOUT = 5
+};
+
+struct InterpolationMethod {
+	InterpolationKind kind = IK_LINEAR;
+	bool loop = false;
+	bool swing = false;
+};
+
+InterpolationMethod intToInterpolationMethod(int value);
+
+static float linear(float t) { return t; }
+
+static float easeIn(float t) {
+	return t * t * t * t;
+}
+
+static float easeOut(float t) {
+	float f = (t - 1.0f);
+	return f * f * f * (1.0f - t) + 1.0f;
+}
+
+static float easeInOut(float t) {
+	if (t < 0.5f)
+		return 8.0f * t * t * t * t;
+	float f = (t - 1.0f);
+	return -8.f * f * f * f * f + 1.f;
+}
+
+inline EasingFunc_t easing(InterpolationKind kind) {
+	switch (kind) {
+	case IK_LINEAR:
+		return {&linear};
+	case IK_EASEIN:
+		return {&easeIn};
+	case IK_EASEINOUT:
+		return {&easeInOut};
+	case IK_EASEOUT:
+		return {&easeOut};
+	case IK_SLOWEASEIN:
+		return {&easeIn};
+	case IK_SLOWEASEOUT:
+		return {&easeOut};
+	}
+	error("Invalid interpolation kind: %d", kind);
+	return {&linear};
+}
+
+} // namespace Twp
+
+#endif