—-<div dir="auto">on karl’s interrupted walking algorithm from 2016 or whatnot during chemotherapy</div><div dir="auto"><br></div><div dir="auto">we’ve been over this before. but it could be fun to actually put it together. what are the parts?</div><div dir="auto"><br></div><div dir="auto">the next part was modelling a concave orthographic projection onto the floor showing what regions the center of mass was stable in.</div><div dir="auto"><br></div><div dir="auto">how to model this? it’s in 2d space. a basic query might be whether or not a point is within it.</div><div dir="auto"><br></div><div dir="auto">i remember the code already existed for paths. could a concave projection be a closed path? does it matter? 1847 i’m thinking it’s pretty normal to assume a polygon. one can always add curves to the polygon with a separate edge class or something.</div><div dir="auto"><br></div><div dir="auto">how to tell if a point is within a convex polygon? shouldn’t i know this?</div><div dir="auto">there is probably optimized code somewhere, but would it maybe help to order the coordinates clockwise or such, and then take the dot product of one of those vectors with another?</div><div dir="auto"><br></div><div dir="auto">i’m thinking maybe for each side, if a point is within the polygon, it will be on the same side of that line or line segment, if they are all treated clockwise or such. then i’m somehow thinking thisncould be tested with a dot product. is this true?</div><div dir="auto"><br></div><div dir="auto">considering: identifying side of point from line between two other points using dot product.</div><div dir="auto">dot product is same-sign when two vectors are &lt;90 degrees different, for them being on left or right of the other, then opposite-sign when two vectors are &gt;90 different, and is 0 at 90 and product magnitude or 1 at 0 and 180 (-1). so if i were to check side using dot product, i might consider valuing the change at 90 degrees. the 0 value is also appropriately ambiguous if a point lays entirely on an edge.</div><div dir="auto">so, we could take the tangent or right angle to the edge, and then dot product that with a vector to the point in question. i guess if all their signs are the same, they’ll be on the same side. it’s an idea</div>