SkeletalAnimatable.hpp

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/*
   Copyright 2022 Rishi Challa
 
   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at
 
       http://www.apache.org/licenses/LICENSE-2.0
 
   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/
 
#pragma once
 
#include <Kale/Math/Transform/Transform.hpp>
#include <Kale/Engine/StateAnimatable/StateAnimatable.hpp>
 
#include <utility>
#include <vector>
#include <tuple>
#include <array>
#include <mutex>
#include <algorithm>
 
namespace Kale {
 
    struct Skeleton {
 
        struct Bone {
            
            Transform worldToBone;
 
            Transform previousToBone;
 
            Transform inverseWorldToBone;
 
            int previousBone;
 
            float length;
 
            float rotation;
        };
        
        std::vector<Bone> bones;
 
        Skeleton();
 
        Skeleton(const std::vector<std::tuple<int, float, float>>& bones, AngleUnit unit);
        
        Skeleton(const std::vector<Bone>& bones);
 
        static Bone calculateBone(const std::vector<Bone>& bones, int previousBone, float length, float rotation, AngleUnit unit) {
            Bone bone;
            bone.previousBone = previousBone;
            bone.length = length;
            bone.rotation = rotation;
            bone.previousToBone = Transform(length, 0.0f, rotation, 1.0f, 1.0f, unit);
            
            // If the bone is the root
            if (previousBone == -1) bone.worldToBone = bone.previousToBone;
            else bone.worldToBone = bone.previousToBone * bones[previousBone].worldToBone;
            bone.inverseWorldToBone = bone.worldToBone.inverse();
            return bone;
        }
 
        static Vector2f transform(const std::vector<Transform>& offsets, Vector2f vert, const std::array<std::pair<int, float>, 4>& weights) {
            Vector2f transformed = Vector2f::zero();
            for (const std::pair<int, float> weight : weights) {
                if (weight.first == -1) break;
                transformed += offsets[weight.first].transform(vert) * weight.second;
            }
            return transformed;
        }
        
    };
 
    class SkeletalAnimatable : public Node, public StateAnimatable<Skeleton> {
    private:
 
        std::vector<Transform> skeleton;
 
        Skeleton base;
 
        bool skeletonRecalculated;
 
        std::mutex mutex;
 
        void recalculateSkeleton(float deltaTime);
 
    protected:
 
        void update(size_t threadNum, const Scene& scene, float deltaTime) override;
 
        void preUpdate(size_t threadNum, const Scene& scene, float deltaTime) override;
 
    public:
 
        SkeletalAnimatable();
 
        SkeletalAnimatable(const Skeleton& base);
 
        void setBase(const Skeleton& skeleton);
 
        const std::vector<Transform>& getSkeleton(float deltaTime);
 
        const std::vector<Transform>& getSkeletonNoRecalc() const;
 
        Vector2f transform(Vector2f vert, const std::array<std::pair<int, float>, 4>& weights, float deltaTime);
 
        Vector2f transformNoRecalc(Vector2f vert, const std::array<std::pair<int, float>, 4>& weights) const;
 
    };
 
}