[{"data":1,"prerenderedAt":312},["ShallowReactive",2],{"project-9969345":3},{"id":4,"name":5,"line":6,"line_source":7,"title":8,"url":9,"domain":5,"maker":10,"posted_at":11,"year":12,"points":13,"comments":14,"rank_in_year":15,"shown_in_year":16,"top":17,"tier":18,"category":19,"subcategory":20,"format":21,"keywords":22,"reception":27,"sentiment":28,"stance_mix":29,"scored_comments":33,"aspects":34,"strip":41,"post_text":43,"what":44,"said":99,"maker_in_thread":192,"shape":202,"grid":205,"attempts":275,"same_week":276,"maker_shows":36,"maker_hidden":304,"reader_version":305,"card":306},"9969345","parametricity.com","Walk around unusual geometries","title","Show HN: Walk around unusual geometries","http:\u002F\u002Fparametricity.com\u002Fpages\u002Fdiffgeo\u002FMain.html","ihm",1438184519,2015,149,34,138,2565,6,"notable","learning_science","interactive math visualisation","web_app",[23,24,25,26],"geodesic","hyperbolic geometry","differential geometry","riemannian manifold","curious",0.061,{"positive":30,"neutral":31,"mixed":32,"critical":30},4,14,0,22,{"design":35,"idea":37,"execution":39,"docs":40},{"positive":36,"critical":32},1,{"positive":38,"critical":32},3,{"positive":32,"critical":38},{"positive":32,"critical":36},[38,42,42,38,32,38,32,32,38,38,38,32,38,32,38,32,32,42,36,32,36,38,32,38,38,32,38,38,32,36,42,36,32,38],5,null,{"problem":45,"audience":61,"pricing":43,"motivation":43,"time_to_build":43,"stack":68,"openness":96,"stage":97,"team_size":98},{"value":46,"source":47,"evidence":48},"Gives intuition for how straight-line motion behaves on curved surfaces and spaces.","inferred",[49,53,57],{"id":50,"by":51,"text":52},"9970240","amelius","Feature request: always show the line that you will walk when you keep going forward (e.g. in a light color).",{"id":54,"by":55,"text":56},"9970767","jameshart","Suggestion: allow me to move in discrete steps of a specified length, and rotate in discrete steps too. Then I can see what happens in different geometries when I go forward n,…",{"id":58,"by":59,"text":60},"9969505","jonahx","Nice work. I'm curious if there are any similar projects which use Oculus\u002FVR to put you in the midst of these strange worlds. I wonder if it could be used to improve your…",{"value":62,"source":47,"evidence":63},"People interested in geometry and curved spaces.",[64,65],{"id":58,"by":59,"text":60},{"id":66,"by":10,"text":67},"9969636","Jeff Weeks has done some excellent stuff. His Curved Spaces[0], lets you fly around funny 3 manifolds. [0]: http:\u002F\u002Fwww.geometrygames.org\u002FCurvedSpaces\u002Findex.html",[69,81,88],{"value":70,"source":71,"evidence":72},"Elm","commenter",[73,77],{"id":74,"by":75,"text":76},"9969777","jacobolus","I think it’s just an artifact of the way the ODE gets discretized. You could probably figure out more precisely by reading the code, though it seems to be written in an ML-like…",{"id":78,"by":79,"text":80},"9969818","bri3d","For the curious (and if it wasn't obvious enough from the file extension), the language is \"Elm\" : http:\u002F\u002Felm-lang.org\u002F",{"value":82,"source":71,"evidence":83},"JavaScript",[84],{"id":85,"by":86,"text":87},"9969876","archgoon","The actual guts of the algorithm are in compiled javascript https:\u002F\u002Fgithub.com\u002Fimeckler\u002Fdiffgeo\u002Fblob\u002Fmaster\u002FNative\u002FODE.js However, this seems to simply be using the numeric…",{"value":89,"source":71,"evidence":90},"numeric.js (Dormand-Prince ODE solver)",[91,92],{"id":85,"by":86,"text":87},{"id":93,"by":94,"text":95},"9970466","conistonwater","Looking at the source code (I think this is it: https:\u002F\u002Fgithub.com\u002Fimeckler\u002Fdiffgeo\u002Fblob\u002Fmaster\u002FMain.elm#L320, https:\u002F\u002Fgithub.com\u002Fimeckler\u002Fdiffgeo\u002Fblob\u002Fmaster\u002FNative\u002FODE.js#L19)…","open_source","launched","unknown",{"praise":100,"objections":101,"requests":138,"questions":169,"alternatives":175},[],[102,117,127],{"value":103,"source":71,"evidence":104},"Numerical inaccuracy causes loops not to close and paths to drift",[105,109,110,114],{"id":106,"by":107,"text":108},"9969883","Gladdyu","Looks really cool! One question though, how did you implement the movement? When you press up and left at the same time in the flat you'd expect to trace the same circle over and…",{"id":93,"by":94,"text":95},{"id":111,"by":112,"text":113},"9969635","cousin_it","Great work! Can you add the Klein model? It's kind of interesting that moving while turning at a constant rate in the hyperbolic plane makes you gradually \"drift\". Is that…",{"id":115,"by":112,"text":116},"9974509","Yeah, I'm pretty sure it's an artifact. I'm seeing the same drift in the cylinder geometry, which definitely shouldn't be happening. A cylinder has the same internal geometry as…",{"value":118,"source":71,"evidence":119},"Page scrollbars flicker and shake in some browsers",[120,124],{"id":121,"by":122,"text":123},"9971444","BHSPitMonkey","I tried this in Firefox (latest) and the scrollbars kept perpetually disappearing\u002Freappearing, causing the entire page to just shake violently.",{"id":125,"by":122,"text":126},"9984368","I'm on Ubuntu 15.04 with Firefox 39.0+build5-0ubuntu0.15.04.1, and with my window maximized the \u003Cbody> alternates between 1411x689px and 1404x689px (with the difference being…",{"value":128,"source":71,"evidence":129},"Zoom controls are not discoverable",[130,134],{"id":131,"by":132,"text":133},"9970512","dbbolton",">Use the up arrow key to go forward along the geodesic in the direction you're facing and the left and right arrow keys to change direction. > >Scroll to zoom, click and drag to…",{"id":135,"by":136,"text":137},"9970574","smeyer","Using a two finger scroll on my touchpad works fine. I'd try that or a scroll wheel on a mouse or similar.",[139,147,151,158,165],{"value":140,"source":71,"evidence":141},"Discrete step and rotation moves, Logo turtle style",[142,143],{"id":54,"by":55,"text":56},{"id":144,"by":145,"text":146},"9970828","dhimes","This is really cool. My suggestion is similar to (perhaps the same as) jameshart's. I want to be able to form a sequence of known steps in flat space (say, draw a square), then…",{"value":148,"source":71,"evidence":149},"Show the path line ahead of the arrow",[150],{"id":50,"by":51,"text":52},{"value":152,"source":71,"evidence":153},"Support moving backwards",[154],{"id":155,"by":156,"text":157},"9972663","blt","Really cool! Yet another feature request: support moving backwards",{"value":159,"source":71,"evidence":160},"Use the arrow's frame of reference",[161],{"id":162,"by":163,"text":164},"9969847","ThrustVectoring","Feature suggestion: use the arrow's frame of reference instead of a global one.",{"value":166,"source":71,"evidence":167},"Add a Klein model view",[168],{"id":111,"by":112,"text":113},[170],{"value":171,"source":71,"evidence":172},"Why do paths drift or fail to be periodic when turning constantly?",[173,174],{"id":106,"by":107,"text":108},{"id":111,"by":112,"text":113},[176,181],{"value":177,"source":178,"evidence":179},"Jeff Weeks' Curved Spaces","maker",[180],{"id":66,"by":10,"text":67},{"value":182,"source":71,"evidence":183},"HyperRogue",[184,188],{"id":185,"by":186,"text":187},"9970329","Filligree","It ain't VR, but check out HyperRogue: A roguelike game in hyperbolic space. http:\u002F\u002Fwww.roguetemple.com\u002Fz\u002Fhyper\u002F",{"id":189,"by":190,"text":191},"9970969","TeMPOraL","This is awesome! Reminds me of a game that was featured recently on HN: HyperRogue[0]. It's a simple roguelike on a hyperbolic plane. [0] - http:\u002F\u002Fwww.roguetemple.com\u002Fz\u002Fhyper\u002F",{"comments":17,"answered":193,"key":194},2,[195,198,201],{"id":196,"text":197},"9969923","Movement is implemented by using approximate numerical solutions to the geodesic equations (a system a differential equations whose solutions give geodesics in a Riemannian…",{"id":199,"text":200},"9972128","A friend of mind suggested the very good idea of solving the diffeq for the constantly turning curve and using this when the user is simultaneously turning and going forward…",{"id":66,"text":67},{"commenters":33,"max_depth":42,"maker_replies":17,"first_comment_mins":203,"lifespan_hours":204},19,53,[206,208,210,211,213,215,216,219,220,222,224,226,227,230,231,232,236,238,239,241,243,244,247,249,251,252,253,254,256,259,260,265,270,273],[50,32,38,207,51,32],"project\u002Fneutral\u002Fdesign",[54,36,42,209,55,32],"project\u002Fpositive\u002Fidea",[144,36,42,209,145,32],[106,193,38,212,107,32],"project\u002Fneutral\u002Fexecution",[196,193,32,214,10,36],"maker\u002Fneutral\u002Fexecution",[93,193,38,212,94,32],[217,193,32,218,75,32],"9970545","other\u002Fneutral\u002Fnone",[199,193,32,212,10,36],[221,193,38,207,75,32],"9972247",[223,193,38,212,94,32],"9974987",[58,38,38,225,59,32],"project\u002Fneutral\u002Fidea",[66,38,32,218,10,36],[228,38,38,225,229,32],"9970278","VLM",[185,38,32,218,186,32],[162,30,38,207,163,32],[233,30,32,234,235,32],"9971738","commenter\u002Fneutral\u002Fexecution","gipp",[237,30,32,234,163,32],"9971921",[189,42,42,209,190,32],[121,17,36,240,122,32],"project\u002Fcritical\u002Fexecution",[242,17,32,214,10,36],"9971576",[125,17,36,240,122,32],[131,245,38,246,132,32],7,"project\u002Fneutral\u002Fdocs",[135,245,32,248,136,32],"commenter\u002Fneutral\u002Fdocs",[111,250,38,212,112,32],8,[74,250,38,212,75,32],[78,250,32,218,79,32],[85,250,38,212,86,32],[255,250,38,212,86,32],"9969973",[257,250,32,258,10,36],"9970074","maker\u002Fpositive\u002Fdesign",[115,250,36,240,112,32],[261,262,42,263,264,32],"9969638",9,"project\u002Fpositive\u002Fdesign","drewolbrich",[266,267,36,268,269,32],"9971078",10,"project\u002Fcritical\u002Fdocs","im3w1l",[271,267,32,272,10,36],"9971171","maker\u002Fneutral\u002Fdocs",[155,274,38,207,156,32],11,[],[277,281,286,291,295,300],{"id":278,"name":279,"points":280,"category":19},"9962185","Spot the Drowning Child",1215,{"id":282,"name":283,"points":284,"category":285},"9944746","Showgoers",281,"consumer_social",{"id":287,"name":288,"points":289,"category":290},"9956415","Meshtag",270,"dev_tools",{"id":292,"name":293,"points":294,"category":19},"9963714","Flexbox.io",236,{"id":296,"name":297,"points":298,"category":299},"9969171","File.io",155,"infrastructure",{"id":301,"name":302,"points":303,"category":19},"9955553","r2d3.us",128,false,"v2",{"id":307,"name":5,"line":6,"ai":304,"cat":19,"year":12,"points":13,"comments":14,"rec":27,"s":308,"top":17,"kw":309,"maker":10,"domain":5,"tier":18,"attempts":32,"strip":310,"url":9,"mix":311,"praise":-1,"objection":103,"sub":20},9969345,0.06,[23,24,25,26],"3553030033303030051013033033015103",[30,31,32,30],1794036533886]