Method GetCellKeys

TombEngine/Specific/Structures/SpatialHash.cpp:241–312

	}

	std::vector<Vector3i> SpatialHash::GetCellKeys(const Ray& ray, float dist) const
	{
		// Reserve minimum key vector.
		auto keys = std::vector<Vector3i>{};
		keys.reserve(int(dist / _cellSize) + 1);

		// Calculate cell position.
		auto pos = Vector3(
			floor(ray.position.x / _cellSize) * _cellSize,
			floor(ray.position.y / _cellSize) * _cellSize,
			floor(ray.position.z / _cellSize) * _cellSize);

		// Calculate cell position step.
		auto posStep = Vector3(
			(ray.direction.x > 0) ? _cellSize : -_cellSize,
			(ray.direction.y > 0) ? _cellSize : -_cellSize,
			(ray.direction.z > 0) ? _cellSize : -_cellSize);

		// Calculate next intersection.
		auto nextIntersect = Vector3(
			((pos.x + ((posStep.x > 0) ? _cellSize : 0)) - ray.position.x) / ray.direction.x,
			((pos.y + ((posStep.y > 0) ? _cellSize : 0)) - ray.position.y) / ray.direction.y,
			((pos.z + ((posStep.z > 0) ? _cellSize : 0)) - ray.position.z) / ray.direction.z);

		// Calculate ray step.
		auto rayStep = Vector3(
			_cellSize / abs(ray.direction.x),
			_cellSize / abs(ray.direction.y),
			_cellSize / abs(ray.direction.z));

		// Traverse cells and collect keys.
		float currentDist = 0.0f;
		while (currentDist <= dist)
		{
			auto key = GetCellKey(pos);
			keys.push_back(key);

			// Determine which axis to step along.
			if (nextIntersect.x < nextIntersect.y)
			{
				if (nextIntersect.x < nextIntersect.z)
				{
					pos.x += posStep.x;
					currentDist = nextIntersect.x;
					nextIntersect.x += rayStep.x;
				}
				else
				{
					pos.z += posStep.z;
					currentDist = nextIntersect.z;
					nextIntersect.z += rayStep.z;
				}
			}
			else
			{
				if (nextIntersect.y < nextIntersect.z)
				{
					pos.y += posStep.y;