I like that phrase, "pay for shadows." Talk to me about paying for shadows.
TL;DRShadows are among the most expensive parts of rendering, costing both GPU and CPU (draw calls) and growing rapidly with each shadow-casting light, so lighting is managed within an overall budget.
Everything has a cost. There's no free lunch in lighting. I don't think I even can get too technical into it because I don't really know. But every light has the option of being a shadow-casting light. And in computer graphics, shadows are generally extremely expensive, one of the more expensive parts of rendering a scene. And so whenever we use shadows, we have to keep in mind how many shadows we're using. The more that you have in the scene at one given time, it can exponentially get more expensive, and it adds a cost both to the GPU in terms of actually rendering the shadows themselves and then also a cost on the CPU for all the additional draw calls that get introduced by the CPU trying to calculate how many extra shadows have to be computed.
Right, the lighting budget, if you would.
Yeah, exactly, the overall lighting budget.