Don't really need vector calculus for this. Geometric intuition is sufficient. It is simply the summation of signed volumes of triangular columns/prisms paralle

Don't really need vector calculus for this. Geometric intuition is sufficient. It is simply the summation of signed volumes of triangular columns/prisms parallel to the X axis. Visualization: https://jsfiddle.net/L7r1hwca/ https://jsfiddle.net/L7r1hwca/ I don't know what they could possibly mean by the naïve algorithms with rendering and sampling (???).