This is a strange one. Using the latest versions of both Microsoft Edge and Google Chrome (i.e. WebGL under Emscripten / WebAssembly) SDL_RenderDrawPoint() and SDL_RenderDrawPoints() are working correctly in 64-bit Windows but are plotting nothing at all in 32-bit Windows! Every other rendering call is working on both as far as I can ascertain.
So this seems to imply that the 32-bit and 64-bit versions of WebGL are behaving differently, which is surprising but I can’t think of any other explanation. Can anybody else confirm this?