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Anyone else confused by the end where it mentions SDFs, says > if you write JavaScript, I think you are already familiar with the idea: then shows sorting an
by tehsauce 5y ago
Anyone else confused by the end where it mentions SDFs,
says
> if you write JavaScript, I think you are already familiar with the idea:
then shows sorting an array with pairs of elements a and b in javascript and says
> And we are calling it “signed distance from b to a”.
what do SDFs have to do with sorting an array?
- fyrn- 5y agoYeah, I've done a lot with SDF, and I don't know what they mean. I guess SDFs and ordering are tengentially related..
- Sidnicious 5y agoI think what the author's getting at is that the function you pass to JavaScript .sort() just returns a number — not special sentinel values — which represents the relative order of two items in the array. By calling that function strategically from a loop, .sort() can sort the array. Similarly, an SDF returns a number that represents how far a point in 3D space is from an object's surface. And, by calling that function strategically from a loop, you can draw a 3D scene using only that function.
- Jasper_ 5y agoThe difference is that .sort() only uses the sign of the return value and ignores the magnitude. Ultimately, all the sort algorithm needs is the boundary condition, e.g. a comparator. The SDF equivalent needs both the sign (is this point inside or outside of this implicit surface), alongside the magnitude, to determine the closest hit. I don't see how they're that interlinked other than saying that signed distance functions are a subset of comparators.