inline void b2DynamicTree::RayCast()

in Box2D/Collision/b2DynamicTree.h [204:287]
63 lines of code
8 McCabe index (conditional complexity)

inline void b2DynamicTree::RayCast(T* callback, const b2RayCastInput& input) const
{
	b2Vec2 p1 = input.p1;
	b2Vec2 p2 = input.p2;
	b2Vec2 r = p2 - p1;
	b2Assert(r.LengthSquared() > 0.0f);
	r.Normalize();

	// v is perpendicular to the segment.
	b2Vec2 v = b2Cross(1.0f, r);
	b2Vec2 abs_v = b2Abs(v);

	// Separating axis for segment (Gino, p80).
	// |dot(v, p1 - c)| > dot(|v|, h)

	float32 maxFraction = input.maxFraction;

	// Build a bounding box for the segment.
	b2AABB segmentAABB;
	{
		b2Vec2 t = p1 + maxFraction * (p2 - p1);
		segmentAABB.lowerBound = b2Min(p1, t);
		segmentAABB.upperBound = b2Max(p1, t);
	}

	b2GrowableStack<int32, 256> stack;
	stack.Push(m_root);

	while (stack.GetCount() > 0)
	{
		int32 nodeId = stack.Pop();
		if (nodeId == b2_nullNode)
		{
			continue;
		}

		const b2TreeNode* node = m_nodes + nodeId;

		if (b2TestOverlap(node->aabb, segmentAABB) == false)
		{
			continue;
		}

		// Separating axis for segment (Gino, p80).
		// |dot(v, p1 - c)| > dot(|v|, h)
		b2Vec2 c = node->aabb.GetCenter();
		b2Vec2 h = node->aabb.GetExtents();
		float32 separation = b2Abs(b2Dot(v, p1 - c)) - b2Dot(abs_v, h);
		if (separation > 0.0f)
		{
			continue;
		}

		if (node->IsLeaf())
		{
			b2RayCastInput subInput;
			subInput.p1 = input.p1;
			subInput.p2 = input.p2;
			subInput.maxFraction = maxFraction;

			float32 value = callback->RayCastCallback(subInput, nodeId);

			if (value == 0.0f)
			{
				// The client has terminated the ray cast.
				return;
			}

			if (value > 0.0f)
			{
				// Update segment bounding box.
				maxFraction = value;
				b2Vec2 t = p1 + maxFraction * (p2 - p1);
				segmentAABB.lowerBound = b2Min(p1, t);
				segmentAABB.upperBound = b2Max(p1, t);
			}
		}
		else
		{
			stack.Push(node->child1);
			stack.Push(node->child2);
		}
	}
}