You only need closed meshes when using an auto LOD because those don't handle open edges very well (though they know which vertices are supposed to be welded). Maybe an engine can use other stuff as well that requires closed meshes but usually, no. I'm not exactly sure what constitutes a surface but AFAIUnderstood all…
okay I posted this over at CG Talk and didn't get a lot or responses so I'll try my luck here. some things i need clarification on... -graphics engines treat objects as surfaces, in effect making all objects open meshes (it's impossible to create totally seamless UV's), so does that mean creating water-tight meshes is…