Frustum Culling

Frustum Culling

void Frustum::FinalUpdate()
{
	Matrix matViewInv = Camera::S_MatView.Invert();
	Matrix matProjectionInv = Camera::S_MatProjection.Invert();
	Matrix matInv = matProjectionInv * matViewInv;

	vector<Vec3> worldPos =
	{
		::XMVector3TransformCoord(Vec3(-1.f, 1.f, 0.f), matInv),
		::XMVector3TransformCoord(Vec3(1.f, 1.f, 0.f), matInv),
		::XMVector3TransformCoord(Vec3(1.f, -1.f, 0.f), matInv),
		::XMVector3TransformCoord(Vec3(-1.f, -1.f, 0.f), matInv),
		::XMVector3TransformCoord(Vec3(-1.f, 1.f, 1.f), matInv),
		::XMVector3TransformCoord(Vec3(1.f, 1.f, 1.f), matInv),
		::XMVector3TransformCoord(Vec3(1.f, -1.f, 1.f), matInv),
		::XMVector3TransformCoord(Vec3(-1.f, -1.f, 1.f), matInv)
	};

	// 평면을 만듦
	_planes[PLANE_FRONT] = ::XMPlaneFromPoints(worldPos[0], worldPos[1], worldPos[2]); // CW
	_planes[PLANE_BACK] = ::XMPlaneFromPoints(worldPos[4], worldPos[7], worldPos[5]); // CCW
	_planes[PLANE_UP] = ::XMPlaneFromPoints(worldPos[4], worldPos[5], worldPos[1]); // CW
	_planes[PLANE_DOWN] = ::XMPlaneFromPoints(worldPos[7], worldPos[3], worldPos[6]); // CCW
	_planes[PLANE_LEFT] = ::XMPlaneFromPoints(worldPos[4], worldPos[0], worldPos[7]); // CW
	_planes[PLANE_RIGHT] = ::XMPlaneFromPoints(worldPos[5], worldPos[6], worldPos[1]); // CCW
}

bool Frustum::ContainsSphere(const Vec3& pos, float radius)
{
	for (const Vec4& plane : _planes)
	{
		// n = (a, b, c)
		Vec3 normal = Vec3(plane.x, plane.y, plane.z);

		// ax + by + cz + d > radius
		if (normal.Dot(pos) + plane.w > radius)
			return false;
	}

	return true;
}





void Camera::Render()
{
	shared_ptr<Scene> scene = GET_SINGLE(SceneManager)->GetActiveScene();

	// TODO : Layer 구분
	const vector<shared_ptr<GameObject>>& gameObjects = scene->GetGameObjects();

	for (auto& gameObject : gameObjects)
	{
		if (gameObject->GetMeshRenderer() == nullptr)
			continue;
		if (gameObject->GetCheckFrustum())
		{
			if (_frustum.ContainsSphere(
				gameObject->GetTransform()->GetWorldPosition(),
				gameObject->GetTransform()->GetBoundingSphereRadius()) == false)
			{
				continue;
			}
		}

		gameObject->GetMeshRenderer()->Render();
	}
}

• Projection Space의 각 평면을 구하여 평면 오브젝트가 내부에 존재하는지 검사한다.

• SkyBox와 같이 Culling과 상관 없이 그려져야 하는 Object의 경우 Frustum Culling을 적용할지에 대한 check값을 만들어 관리한다.