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/**************************************************************************/
/* transform_interpolator.cpp */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
#include "transform_interpolator.h"
#include "core/math/transform_2d.h"
void TransformInterpolator::interpolate_transform_2d(const Transform2D &p_prev, const Transform2D &p_curr, Transform2D &r_result, real_t p_fraction) {
// Extract parameters.
Vector2 p1 = p_prev.get_origin();
Vector2 p2 = p_curr.get_origin();
// Special case for physics interpolation, if flipping, don't interpolate basis.
// If the determinant polarity changes, the handedness of the coordinate system changes.
if (_sign(p_prev.determinant()) != _sign(p_curr.determinant())) {
r_result.columns[0] = p_curr.columns[0];
r_result.columns[1] = p_curr.columns[1];
r_result.set_origin(p1.lerp(p2, p_fraction));
return;
}
real_t r1 = p_prev.get_rotation();
real_t r2 = p_curr.get_rotation();
Size2 s1 = p_prev.get_scale();
Size2 s2 = p_curr.get_scale();
// Slerp rotation.
Vector2 v1(Math::cos(r1), Math::sin(r1));
Vector2 v2(Math::cos(r2), Math::sin(r2));
real_t dot = v1.dot(v2);
dot = CLAMP(dot, -1, 1);
Vector2 v;
if (dot > 0.9995f) {
v = v1.lerp(v2, p_fraction).normalized(); // Linearly interpolate to avoid numerical precision issues.
} else {
real_t angle = p_fraction * Math::acos(dot);
Vector2 v3 = (v2 - v1 * dot).normalized();
v = v1 * Math::cos(angle) + v3 * Math::sin(angle);
}
// Construct matrix.
r_result = Transform2D(Math::atan2(v.y, v.x), p1.lerp(p2, p_fraction));
r_result.scale_basis(s1.lerp(s2, p_fraction));
}
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