godot/scene/3d/ccd_ik_3d.cpp

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/*  ccd_ik_3d.cpp                                                         */
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/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#include "ccd_ik_3d.h"

void CCDIK3D::_solve_iteration(double p_delta, Skeleton3D *p_skeleton, IterateIK3DSetting *p_setting, const Vector3 &p_destination) {
	int joint_size = (int)p_setting->joints.size();
	int chain_size = (int)p_setting->chain.size();

	// Backwards.
	for (int ancestor = joint_size - 1; ancestor >= 0; ancestor--) {
		// Forwards.
		for (int i = ancestor; i < joint_size; i++) {
			IKModifier3DSolverInfo *solver_info = p_setting->solver_info_list[i];
			if (!solver_info || Math::is_zero_approx(solver_info->length)) {
				continue;
			}

			int HEAD = i;
			int TAIL = i + 1;

			Vector3 current_head = p_setting->chain[HEAD];
			Vector3 current_effector = p_setting->chain[chain_size - 1];
			Vector3 head_to_effector = current_effector - current_head;
			Vector3 head_to_destination = p_destination - current_head;

			if (Math::is_zero_approx(head_to_destination.length_squared() * head_to_effector.length_squared())) {
				continue;
			}

			Quaternion to_rot = Quaternion(head_to_effector.normalized(), head_to_destination.normalized());
			Vector3 to_tail = p_setting->chain[TAIL] - current_head;

			p_setting->update_chain_coordinate_fw(p_skeleton, TAIL, current_head + to_rot.xform(to_tail));

			if (p_setting->joint_settings[HEAD]->rotation_axis != ROTATION_AXIS_ALL) {
				p_setting->update_chain_coordinate_fw(p_skeleton, TAIL, p_setting->chain[HEAD] + p_setting->joint_settings[HEAD]->get_projected_rotation(solver_info->current_grest, p_setting->chain[TAIL] - p_setting->chain[HEAD]));
			}
			if (p_setting->joint_settings[HEAD]->limitation.is_valid()) {
				p_setting->update_chain_coordinate_fw(p_skeleton, TAIL, p_setting->chain[HEAD] + p_setting->joint_settings[HEAD]->get_limited_rotation(solver_info->current_grest, p_setting->chain[TAIL] - p_setting->chain[HEAD], solver_info->forward_vector));
			}
		}
	}
}