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/*
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* Copyright (C) 2023 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <engine/animation/ik/constraints/swing-twist-ik-constraint.hpp>
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#include <cmath>
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void swing_twist_ik_constraint::set_twist_limit(float angle_min, float angle_max)
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{
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m_cos_half_twist_min = std::cos(angle_min * 0.5f);
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m_sin_half_twist_min = std::sin(angle_min * 0.5f);
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m_cos_half_twist_max = std::cos(angle_max * 0.5f);
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m_sin_half_twist_max = std::sin(angle_max * 0.5f);
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}
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void swing_twist_ik_constraint::solve(math::fquat& q)
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{
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constexpr math::fvec3 twist_axis{0.0f, 0.0f, 1.0f};
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// Decompose rotation into swing and twist components
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math::fquat swing;
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math::fquat twist;
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math::swing_twist(q, twist_axis, swing, twist);
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// Limit twist
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if (twist.z() < m_sin_half_twist_min)
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{
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twist.z() = m_sin_half_twist_min;
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twist.w() = m_cos_half_twist_min;
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}
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else if (twist.z() > m_sin_half_twist_max)
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{
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twist.z() = m_sin_half_twist_max;
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twist.w() = m_cos_half_twist_max;
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}
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// Re-compose rotation from swing and twist components
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q = math::normalize(swing * twist);
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}
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