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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
commit36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree105e8c98ddea1c1e4784a60a5a6410fa416be2de /gfx/layers/AxisPhysicsModel.h
parentInitial commit. (diff)
downloadfirefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz
firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip
Adding upstream version 115.7.0esr.upstream/115.7.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_AxisPhysicsModel_h
+#define mozilla_layers_AxisPhysicsModel_h
+
+#include <sys/types.h> // for int32_t
+#include "mozilla/TimeStamp.h" // for TimeDuration
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * AxisPhysicsModel encapsulates a generic 1-dimensional physically-based motion
+ * model.
+ *
+ * It performs frame-rate independent interpolation and RK4 integration for
+ * smooth animation with stable, deterministic behavior.
+ * Implementations are expected to subclass and override the Acceleration()
+ * method.
+ */
+class AxisPhysicsModel {
+ public:
+ AxisPhysicsModel(double aInitialPosition, double aInitialVelocity);
+ virtual ~AxisPhysicsModel();
+
+ /**
+ * Advance the physics simulation.
+ * |aDelta| is the time since the last sample.
+ */
+ void Simulate(const TimeDuration& aDeltaTime);
+
+ /**
+ * Gets the raw velocity of this axis at this moment.
+ */
+ double GetVelocity() const;
+
+ /**
+ * Sets the raw velocity of this axis at this moment.
+ */
+ void SetVelocity(double aVelocity);
+
+ /**
+ * Gets the raw position of this axis at this moment.
+ */
+ double GetPosition() const;
+
+ /**
+ * Sets the raw position of this axis at this moment.
+ */
+ void SetPosition(double aPosition);
+
+ protected:
+ struct State {
+ State(double ap, double av) : p(ap), v(av){};
+ double p; // Position
+ double v; // Velocity
+ };
+
+ struct Derivative {
+ Derivative() : dp(0.0), dv(0.0){};
+ Derivative(double aDp, double aDv) : dp(aDp), dv(aDv){};
+ double dp; // dp / delta time = Position
+ double dv; // dv / delta time = Velocity
+ };
+
+ /**
+ * Acceleration must be overridden and return the number of
+ * axis-position-units / second that should be added or removed from the
+ * velocity.
+ */
+ virtual double Acceleration(const State& aState) = 0;
+
+ private:
+ /**
+ * Duration of fixed delta time step (seconds)
+ */
+ static const double kFixedTimestep;
+
+ /**
+ * 0.0 - 1.0 value indicating progress between current and next simulation
+ * sample. Normalized to units of kFixedTimestep duration.
+ */
+ double mProgress;
+
+ /**
+ * Sample of simulation state as it existed
+ * (1.0 - mProgress) * kFixedTimestep seconds in the past.
+ */
+ State mPrevState;
+
+ /**
+ * Sample of simulation state as it will be in mProgress * kFixedTimestep
+ * seconds in the future.
+ */
+ State mNextState;
+
+ /**
+ * Perform RK4 (Runge-Kutta method) Integration to calculate the next
+ * simulation sample.
+ */
+ void Integrate(double aDeltaTime);
+
+ /**
+ * Apply delta velocity and position represented by aDerivative over
+ * aDeltaTime seconds, calculate new acceleration, and return new deltas.
+ */
+ Derivative Evaluate(const State& aInitState, double aDeltaTime,
+ const Derivative& aDerivative);
+
+ /**
+ * Helper function for performing linear interpolation (lerp) of double's
+ */
+ static double LinearInterpolate(double aV1, double aV2, double aBlend);
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif