Function CDrawLegImpl

Source/Objects/movementobject.cpp:2826–2892

}

static void CDrawLegImpl(
    RiggedObject& rigged_object,
    Skeleton& skeleton,
    CScriptArrayWrapper<int>& ik_chain_start_index,
    CScriptArrayWrapper<int>& ik_chain_elements,
    CScriptArrayWrapper<float>& ik_chain_bone_lengths,
    CScriptArrayWrapper<BoneTransform>& skeleton_bind_transforms,
    CScriptArrayWrapper<BoneTransform>& inv_skeleton_bind_transforms,
    bool right, const BoneTransform& hip_transform, const BoneTransform& foot_transform) {
    int ik_chain_start = ik_chain_start_index[kLeftLegIK + (right ? 1 : 0)];

    // Get important joint positions
    vec3 foot_tip, foot_base, ankle, knee, hip;
    foot_tip = GetTransformedBonePoint(&rigged_object, ik_chain_elements[ik_chain_start + 0], 1);
    foot_base = GetTransformedBonePoint(&rigged_object, ik_chain_elements[ik_chain_start + 0], 0);
    ankle = GetTransformedBonePoint(&rigged_object, ik_chain_elements[ik_chain_start + 1], 0);
    knee = GetTransformedBonePoint(&rigged_object, ik_chain_elements[ik_chain_start + 3], 0);
    hip = GetTransformedBonePoint(&rigged_object, ik_chain_elements[ik_chain_start + 5], 0);

    vec3 old_foot_dir = foot_tip - foot_base;
    float upper_foot_length = ik_chain_bone_lengths[ik_chain_start + 1];
    float lower_leg_length = (ik_chain_bone_lengths[ik_chain_start + 2] + ik_chain_bone_lengths[ik_chain_start + 3]);
    float upper_leg_length = (ik_chain_bone_lengths[ik_chain_start + 4] + ik_chain_bone_lengths[ik_chain_start + 5]);

    float lower_leg_weight = ik_chain_bone_lengths[ik_chain_start + 2] / lower_leg_length;
    float upper_leg_weight = ik_chain_bone_lengths[ik_chain_start + 4] / upper_leg_length;

    vec3 old_hip = hip;
    float old_length = distance(foot_base, old_hip);

    // New hip position based on key hip transform
    hip = hip_transform * skeleton.points[skeleton.bones[ik_chain_elements[ik_chain_start + 5]].points[0]];

    // New foot_base position based on key foot transform
    vec3 ik_target = foot_transform * skeleton.points[skeleton.bones[ik_chain_elements[ik_chain_start + 0]].points[0]];

    quaternion rotate;
    GetRotationBetweenVectors(foot_base - old_hip, ik_target - hip, rotate);
    mat3 rotate_mat = Mat3FromQuaternion(rotate);
    knee = rotate_mat * (knee - old_hip) + hip;
    ankle = rotate_mat * (ankle - old_hip) + hip;
    foot_base = rotate_mat * (foot_base - old_hip) + hip;
    float new_length = distance(ik_target, hip);
    float weight = new_length / old_length;
    knee = mix(hip, knee, weight);
    ankle = mix(hip, ankle, weight);
    foot_base = mix(hip, foot_base, weight);
    foot_tip = foot_transform * skeleton.points[skeleton.bones[ik_chain_elements[ik_chain_start + 0]].points[1]];

    int num_iterations = 2;

    for (int i = 0; i < num_iterations; ++i) {
        knee = hip + normalize(knee - hip) * upper_leg_length;
        ankle = foot_base + normalize(ankle - foot_base) * upper_foot_length;
        vec3 knee_ankle_vec = normalize(knee - ankle);
        vec3 mid = (knee + ankle) * 0.5f;
        ankle = mid - knee_ankle_vec * 0.5f * lower_leg_length;
        knee = mid + knee_ankle_vec * 0.5f * lower_leg_length;