[DirectX12] 25) Picking

Picking = Raycasting

 

좌표 파이프라인을 반대로 다시 돌아가면 된다.

 

Actual Viewport → Normalized Coordination Space → View Space

 

View Space에서 Picking을 진행하게 됨

 

Ray와 물체가 충돌하는지에 대해서 확인이 필요함

---

BaseCollider

#pragma once
#include "Component.h"

enum class ColliderType
{
	Sphere,
};

class BaseCollider : public Component
{
public:
	BaseCollider(ColliderType colliderType);
	virtual ~BaseCollider();

	virtual bool Intersects(Vec4 rayOrigin, Vec4 rayDir, OUT float& distance) = 0;

private:
	ColliderType _colliderType = {};
};

---

SphereCollider.h

#pragma once
#include "BaseCollider.h"

class SphereCollider : public BaseCollider
{
public:
	SphereCollider();
	virtual ~SphereCollider();

	virtual void FinalUpdate() override;
	virtual bool Intersects(Vec4 rayOrigin, Vec4 rayDir, OUT float& distance) override;

	void SetRadius(float radius) { _radius = radius; }
	void SetCenter(Vec3 center) { _center = center; }

private:
	// Local 기준
	float		_radius = 1.f;
	Vec3		_center = Vec3(0, 0, 0);

	BoundingSphere _boundingSphere;
};

SphereCollider.cpp

#include "pch.h"
#include "SphereCollider.h"
#include "GameObject.h"
#include "Transform.h"

SphereCollider::SphereCollider() : BaseCollider(ColliderType::Sphere)
{

}

SphereCollider::~SphereCollider()
{

}

void SphereCollider::FinalUpdate()
{
	_boundingSphere.Center = GetGameObject()->GetTransform()->GetWorldPosition();

	Vec3 scale = GetGameObject()->GetTransform()->GetLocalScale();
	_boundingSphere.Radius = _radius * max(max(scale.x, scale.y), scale.z);
}

bool SphereCollider::Intersects(Vec4 rayOrigin, Vec4 rayDir, OUT float& distance)
{
	return _boundingSphere.Intersects(rayOrigin, rayDir, OUT distance);
}

---

SceneManager.cpp

Pick 메소드

1. Main Camera, Width, Height 를 가져옴
2. 이후 ViewSpace 에서 Picking에 필요한 공식을 적용
3. 다시 WorldSpace를 돌아가기 위해 view 행렬을 가져온 뒤 역행렬을 구함
4. ViewSpace 기준으로 Ray를 정의함(rayOrigin : 카메라 기준, rayDir 방향)
5. 역행렬을 이용하여 WorldSpace 기준으로 Ray를 정의함
6. WorldSpace에서의 연산
7. 충돌테스트

shared_ptr<GameObject> SceneManager::Pick(int32 screenX, int32 screenY)
{
	shared_ptr<Camera> camera = GetActiveScene()->GetMainCamera();

	float width = static_cast<float>(GEngine->GetWindow().width);
	float height = static_cast<float>(GEngine->GetWindow().height);

	Matrix projectionMatrix = camera->GetProjectionMatrix();

	// ViewSpace에서 Picking 진행
	float viewX = (+2.0f * screenX / width - 1.0f) / projectionMatrix(0, 0);
	float viewY = (-2.0f * screenY / height + 1.0f) / projectionMatrix(1, 1);

	Matrix viewMatrix = camera->GetViewMatrix();
	Matrix viewMatrixInv = viewMatrix.Invert();

	auto& gameObjects = GET_SINGLE(SceneManager)->GetActiveScene()->GetGameObjects();

	float minDistance = FLT_MAX;
	shared_ptr<GameObject> picked;

	for (auto& gameObject : gameObjects)
	{
		if (gameObject->GetCollider() == nullptr)
			continue;

		// ViewSpace에서의 Ray 정의
		Vec4 rayOrigin = Vec4(0.0f, 0.0f, 0.0f, 1.0f);
		Vec4 rayDir = Vec4(viewX, viewY, 1.0f, 0.0f);

		// WorldSpace에서의 Ray 정의
		rayOrigin = XMVector3TransformCoord(rayOrigin, viewMatrixInv);
		rayDir = XMVector3TransformNormal(rayDir, viewMatrixInv);
		rayDir.Normalize();

		// WorldSpace에서 연산
		float distance = 0.f;
		if (gameObject->GetCollider()->Intersects(rayOrigin, rayDir, OUT distance) == false)
			continue;

		if (distance < minDistance)
		{
			minDistance = distance;
			picked = gameObject;
		}
	}

	return picked;
}