TransformComponent.hpp

#pragma once
 
#include <glm/gtx/transform.hpp>
#include <glm/gtx/quaternion.hpp>
#include "EngineCore/Reflection/ComponentReflection.hpp"
#include "Common/Math.hpp"
 
#include <EngineCore/ECS/Entity.hpp>
#include <EngineCore/CoreComponents/Parent/ParentComponent.hpp>
 
namespace Grindstone {
    struct TransformComponent {
        Math::Quaternion rotation = Math::Quaternion(0.0f, 0.0f, 0.0f, 1.0f);
        Math::Float3 position = Math::Float3(0.0f, 0.0f, 0.0f);
        Math::Float3 scale = Math::Float3(1.f, 1.f, 1.f);
 
        static Math::Matrix4 GetWorldTransformMatrix(ECS::Entity entity) {
            return GetWorldTransformMatrix(entity.GetHandle(), entity.GetSceneEntityRegistry());
        }
 
        static Math::Matrix4 GetWorldTransformMatrix(entt::entity entity, const entt::registry& registry) {
            Math::Matrix4 matrix = Math::Matrix4(1.0f);
            entt::entity currentEntity = entity;
            while (currentEntity != entt::null) {
                const TransformComponent* transformComp = registry.try_get<TransformComponent>(currentEntity);
                if (transformComp == nullptr) {
                    break;
                }
 
                matrix = transformComp->GetTransformMatrix() * matrix;
 
                const ParentComponent* parentComp = registry.try_get<ParentComponent>(currentEntity);
                if (parentComp == nullptr) {
                    break;
                }
 
                currentEntity = parentComp->parentEntity;
            }
 
            return matrix;
        }
 
        static Math::Float3 GetWorldPosition(const ECS::Entity entity) {
            return GetWorldPosition(entity.GetHandle(), entity.GetSceneEntityRegistry());
        }
 
        static Math::Float3 GetWorldPosition(const entt::entity entity, const entt::registry& registry) {
            Math::Matrix4 worldMatrix = GetWorldTransformMatrix(entity, registry);
 
            return Math::Float3(worldMatrix[3][0], worldMatrix[3][1], worldMatrix[3][2]);
        }
 
        void SetLocalMatrix(Math::Matrix4 localMatrix) {
            rotation = Math::Quaternion(localMatrix);
 
            for (int i = 0; i < 3; i++) {
                position[i] = localMatrix[3][i];
 
                scale[i] = glm::sqrt(
                    localMatrix[i][0] * localMatrix[i][0]
                    + localMatrix[i][1] * localMatrix[i][1]
                    + localMatrix[i][2] * localMatrix[i][2]);
            }
        }
 
        void SetWorldMatrixRelativeTo(Math::Matrix4 newWorldMatrix, Math::Matrix4 parentMatrix) {
            Math::Matrix4 localMatrix = glm::inverse(parentMatrix) * newWorldMatrix;
            SetLocalMatrix(localMatrix);
        }
 
        Math::Matrix4 GetTransformMatrix() const {
            return glm::translate(position) *
                glm::toMat4(rotation) *
                glm::scale(scale);
        }
 
        Math::Float3 GetForward() const {
            return rotation * Math::Float3(0.0f, 0.0f, 1.0f);
        }
 
        Math::Float3 GetRight() const {
            return rotation * Math::Float3(1.0f, 0.0f, 0.0f);
        }
 
        Math::Float3 GetUp() const {
            return rotation * Math::Float3(0.0f, 1.0f, 0.0f);
        }
 
        REFLECT("Transform")
    };
}