/**************************************************************************/
/* two_bone_ik_3d.h */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
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/* 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 */
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#pragma once
#include "scene/3d/ik_modifier_3d.h"
class TwoBoneIK3D : public IKModifier3D {
GDCLASS(TwoBoneIK3D, IKModifier3D);
public:
struct TwoBoneIK3DSetting : public IKModifier3DSetting {
bool joints_dirty = false;
BoneJoint root_bone;
BoneJoint middle_bone;
BoneJoint end_bone;
// To make virtual end joint.
bool use_virtual_end = false;
bool extend_end_bone = false;
BoneDirection end_bone_direction = BONE_DIRECTION_FROM_PARENT;
float end_bone_length = 0.0;
NodePath pole_node;
SecondaryDirection pole_direction = SECONDARY_DIRECTION_NONE; // Sort to pole target plane.
Vector3 pole_direction_vector; // Custom vector.
NodePath target_node;
IKModifier3DSolverInfo *root_joint_solver_info = nullptr;
IKModifier3DSolverInfo *mid_joint_solver_info = nullptr;
Vector3 root_pos;
Vector3 mid_pos;
Vector3 end_pos;
// To process.
bool simulation_dirty = true;
double cached_length_sq = 0.0;
bool is_valid() const {
return root_joint_solver_info && mid_joint_solver_info;
}
bool is_end_valid() const {
return (!use_virtual_end && end_bone.bone != -1) || (use_virtual_end && !Math::is_zero_approx(end_bone_length));
}
int get_end_bone() const {
return use_virtual_end ? middle_bone.bone : end_bone.bone; // Hack, but useful for external class such as TwoBoneIK3DGizmoPlugin.
}
Vector3 get_pole_direction_vector() const {
Vector3 ret;
switch (pole_direction) {
case SECONDARY_DIRECTION_NONE:
ret = Vector3(0, 0, 0);
break;
case SECONDARY_DIRECTION_PLUS_X:
ret = Vector3(1, 0, 0);
break;
case SECONDARY_DIRECTION_MINUS_X:
ret = Vector3(-1, 0, 0);
break;
case SECONDARY_DIRECTION_PLUS_Y:
ret = Vector3(0, 1, 0);
break;
case SECONDARY_DIRECTION_MINUS_Y:
ret = Vector3(0, -1, 0);
break;
case SECONDARY_DIRECTION_PLUS_Z:
ret = Vector3(0, 0, 1);
break;
case SECONDARY_DIRECTION_MINUS_Z:
ret = Vector3(0, 0, -1);
break;
case SECONDARY_DIRECTION_CUSTOM:
ret = pole_direction_vector;
break;
}
return ret;
}
void cache_current_vectors(Skeleton3D *p_skeleton) {
if (!is_valid()) {
return;
}
root_joint_solver_info->current_vector = (mid_pos - root_pos).normalized();
mid_joint_solver_info->current_vector = (end_pos - mid_pos).normalized();
}
void init_current_joint_rotations(Skeleton3D *p_skeleton) {
if (!is_valid()) {
return;
}
Quaternion parent_gpose;
int parent = p_skeleton->get_bone_parent(root_bone.bone);
if (parent >= 0) {
parent_gpose = p_skeleton->get_bone_global_pose(parent).basis.get_rotation_quaternion();
}
root_joint_solver_info->current_lrest = p_skeleton->get_bone_pose(root_bone.bone).basis.get_rotation_quaternion();
root_joint_solver_info->current_grest = parent_gpose * root_joint_solver_info->current_lrest;
root_joint_solver_info->current_grest.normalize();
root_joint_solver_info->current_lpose = p_skeleton->get_bone_pose(root_bone.bone).basis.get_rotation_quaternion();
root_joint_solver_info->current_gpose = parent_gpose * root_joint_solver_info->current_lpose;
root_joint_solver_info->current_gpose.normalize();
parent_gpose = root_joint_solver_info->current_gpose;
// Mid joint pose is relative to the root joint pose.
mid_joint_solver_info->current_lrest = p_skeleton->get_bone_global_pose(root_bone.bone).basis.get_rotation_quaternion().inverse() * p_skeleton->get_bone_global_pose(middle_bone.bone).basis.get_rotation_quaternion();
mid_joint_solver_info->current_grest = parent_gpose * mid_joint_solver_info->current_lrest;
mid_joint_solver_info->current_grest.normalize();
mid_joint_solver_info->current_lpose = p_skeleton->get_bone_global_pose(root_bone.bone).basis.get_rotation_quaternion().inverse() * p_skeleton->get_bone_global_pose(middle_bone.bone).basis.get_rotation_quaternion();
mid_joint_solver_info->current_gpose = parent_gpose * mid_joint_solver_info->current_lpose;
mid_joint_solver_info->current_gpose.normalize();
cache_current_vectors(p_skeleton);
}
// Make rotation as bone pose from chain coordinates.
void cache_current_joint_rotations(Skeleton3D *p_skeleton, const Vector3 &p_pole_destination) {
if (!is_valid()) {
return;
}
Quaternion parent_gpose;
int parent = p_skeleton->get_bone_parent(root_bone.bone);
if (parent >= 0) {
parent_gpose = p_skeleton->get_bone_global_pose(parent).basis.get_rotation_quaternion();
}
root_joint_solver_info->current_lrest = p_skeleton->get_bone_pose(root_bone.bone).basis.get_rotation_quaternion();
root_joint_solver_info->current_grest = parent_gpose * root_joint_solver_info->current_lrest;
root_joint_solver_info->current_grest.normalize();
Vector3 from = root_joint_solver_info->forward_vector;
Vector3 to = root_joint_solver_info->current_grest.xform_inv(root_joint_solver_info->current_vector).normalized();
root_joint_solver_info->current_lpose = root_joint_solver_info->current_lrest * get_swing(Quaternion(from, to), from);
root_joint_solver_info->current_gpose = parent_gpose * root_joint_solver_info->current_lpose;
root_joint_solver_info->current_gpose.normalize();
Quaternion root_gpose = root_joint_solver_info->current_gpose;
// Mid joint pose is relative to the root joint pose for the case root-mid or mid-end have more than 1 joints.
mid_joint_solver_info->current_lrest = p_skeleton->get_bone_global_pose(root_bone.bone).basis.get_rotation_quaternion().inverse() * p_skeleton->get_bone_global_pose(middle_bone.bone).basis.get_rotation_quaternion();
mid_joint_solver_info->current_grest = root_gpose * mid_joint_solver_info->current_lrest;
mid_joint_solver_info->current_grest.normalize();
from = mid_joint_solver_info->forward_vector;
to = mid_joint_solver_info->current_grest.xform_inv(mid_joint_solver_info->current_vector).normalized();
mid_joint_solver_info->current_lpose = mid_joint_solver_info->current_lrest * get_swing(Quaternion(from, to), from);
mid_joint_solver_info->current_gpose = root_gpose * mid_joint_solver_info->current_lpose;
mid_joint_solver_info->current_gpose.normalize();
bool is_pole_defined = pole_direction != SECONDARY_DIRECTION_NONE && (pole_direction != SECONDARY_DIRECTION_CUSTOM || !pole_direction_vector.is_zero_approx());
// Fix roll to align pole vector to plane.
if (is_pole_defined) {
// Calc roll angles.
Quaternion root_roll_rot = Quaternion();
Quaternion mid_roll_rot = Quaternion();
// Make roll to align pole_vector onto plane with selecting the point nearer pole_destination.
Vector3 pole_dir = get_projected_normal(root_pos, end_pos, p_pole_destination);
if (pole_dir.is_zero_approx()) {
return;
}
Vector3 a = mid_joint_solver_info->current_vector.normalized(); // Global roll axis (mid forward in current pose).
Vector3 k = mid_joint_solver_info->current_gpose.xform(get_pole_direction_vector()).normalized(); // Global pole vector.
Vector3 n = pole_dir.cross((mid_pos - root_pos).normalized()).normalized(); // Global plane normal.
// Guard: degenerate cases (zero or already parallel)
if (a.is_zero_approx() || k.is_zero_approx() || n.is_zero_approx() || Math::is_zero_approx(n.dot(k))) {
return;
}
// c0 cosθ + c1 sinθ + c2 = 0
double c0 = n.dot(k - a * k.dot(a)); // n·(k⊥a)
double c1 = n.dot(a.cross(k)); // n·(a×k)
double c2 = n.dot(a) * k.dot(a); // (n·a)(k·a)
double r = Math::sqrt(c0 * c0 + c1 * c1);
double cos_arg = CLAMP(-c2 / r, -1.0, 1.0);
double phi = Math::atan2(c1, c0);
double acosv = Math::acos(cos_arg);
// Two candidate angles.
double t1 = phi + acosv;
double t2 = phi - acosv;
Quaternion q1(a, t1);
Quaternion q2(a, t2);
// Choose the one whose projected pole points closer to pole side.
Vector3 pole_proj = snap_vector_to_plane(n, pole_dir).normalized();
Vector3 k1p = snap_vector_to_plane(n, q1.xform(k)).normalized();
Vector3 k2p = snap_vector_to_plane(n, q2.xform(k)).normalized();
double s1 = pole_proj.is_zero_approx() ? Math::abs(t1) : k1p.dot(pole_proj);
double s2 = pole_proj.is_zero_approx() ? Math::abs(t2) : k2p.dot(pole_proj);
double t = s1 >= s2 ? t1 : t2;
root_roll_rot = Quaternion(root_joint_solver_info->forward_vector, t);
mid_roll_rot = Quaternion(mid_joint_solver_info->forward_vector, t);
root_joint_solver_info->current_lpose = root_joint_solver_info->current_lpose * root_roll_rot;
root_joint_solver_info->current_gpose = parent_gpose * root_joint_solver_info->current_lpose;
root_joint_solver_info->current_gpose.normalize();
root_gpose = root_joint_solver_info->current_gpose;
mid_joint_solver_info->current_lpose = root_roll_rot.inverse() * mid_joint_solver_info->current_lpose * mid_roll_rot;
mid_joint_solver_info->current_gpose = root_gpose * mid_joint_solver_info->current_lpose;
mid_joint_solver_info->current_gpose.normalize();
}
}
};
protected:
LocalVector<TwoBoneIK3DSetting *> tb_settings;
bool _get(const StringName &p_path, Variant &r_ret) const;
bool _set(const StringName &p_path, const Variant &p_value);
void _get_property_list(List<PropertyInfo> *p_list) const;
void _validate_dynamic_prop(PropertyInfo &p_property) const;
static void _bind_methods();
virtual void _validate_bone_names() override;
void _validate_pole_directions(Skeleton3D *p_skeleton) const;
void _validate_pole_direction(Skeleton3D *p_skeleton, int p_index) const;
virtual void _make_all_joints_dirty() override;
virtual void _init_joints(Skeleton3D *p_skeleton, int p_index) override;
void _clear_joints(int p_index);
virtual void _update_joints(int p_index) override;
virtual void _make_simulation_dirty(int p_index) override;
virtual void _update_bone_axis(Skeleton3D *p_skeleton, int p_index) override;
virtual void _process_ik(Skeleton3D *p_skeleton, double p_delta) override;
void _process_joints(double p_delta, Skeleton3D *p_skeleton, TwoBoneIK3DSetting *p_setting, const Vector3 &p_destination, const Vector3 &p_pole_destination);
Transform3D _get_bone_global_rest(Skeleton3D *p_skeleton, int p_bone, int p_root) const;
public:
virtual PackedStringArray get_configuration_warnings() const override;
virtual void set_setting_count(int p_count) override {
_set_setting_count<TwoBoneIK3DSetting>(p_count);
tb_settings = _cast_settings<TwoBoneIK3DSetting>();
}
virtual void clear_settings() override {
_set_setting_count<TwoBoneIK3DSetting>(0);
tb_settings.clear();
}
// Setting.
void set_root_bone_name(int p_index, const String &p_bone_name);
String get_root_bone_name(int p_index) const;
void set_root_bone(int p_index, int p_bone);
int get_root_bone(int p_index) const;
void set_middle_bone_name(int p_index, const String &p_bone_name);
String get_middle_bone_name(int p_index) const;
void set_middle_bone(int p_index, int p_bone);
int get_middle_bone(int p_index) const;
void set_end_bone_name(int p_index, const String &p_bone_name);
String get_end_bone_name(int p_index) const;
void set_end_bone(int p_index, int p_bone);
int get_end_bone(int p_index) const;
void set_use_virtual_end(int p_index, bool p_enabled);
bool is_using_virtual_end(int p_index) const;
void set_extend_end_bone(int p_index, bool p_enabled);
bool is_end_bone_extended(int p_index) const;
void set_end_bone_direction(int p_index, BoneDirection p_bone_direction);
BoneDirection get_end_bone_direction(int p_index) const;
void set_end_bone_length(int p_index, float p_length);
float get_end_bone_length(int p_index) const;
void set_target_node(int p_index, const NodePath &p_target_node);
NodePath get_target_node(int p_index) const;
void set_pole_node(int p_index, const NodePath &p_pole_node);
NodePath get_pole_node(int p_index) const;
void set_pole_direction(int p_index, SecondaryDirection p_axis);
SecondaryDirection get_pole_direction(int p_index) const;
void set_pole_direction_vector(int p_index, const Vector3 &p_vector);
Vector3 get_pole_direction_vector(int p_index) const;
bool is_valid(int p_index) const; // Helper for editor and validation.
#ifdef TOOLS_ENABLED
Vector3 get_root_bone_vector(int p_index) const;
Vector3 get_middle_bone_vector(int p_index) const;
#endif // TOOLS_ENABLED
~TwoBoneIK3D();
};