{"id":1642,"date":"2014-01-27T21:38:19","date_gmt":"2014-01-27T20:38:19","guid":{"rendered":"http:\/\/cb.nowan.net\/blog\/?p=1642"},"modified":"2014-01-27T21:48:50","modified_gmt":"2014-01-27T20:48:50","slug":"creating-vr-games-the-fundamentals","status":"publish","type":"post","link":"http:\/\/cb.nowan.net\/blog\/2014\/01\/27\/creating-vr-games-the-fundamentals\/","title":{"rendered":"Creating VR games &#8211; the fundamentals"},"content":{"rendered":"[This is a re-post of <a href=\"http:\/\/gamedeveloper.com\/view\/feature\/192810\/creating_virtual_reality_games_.php\">the original Gamasutra article<\/a> which was published on <strong>May 23, 2013<\/strong>]\n<p>When I was on a field trip to London back in high school, I played my first virtual reality (VR) game: <a href=\"http:\/\/www.youtube.com\/watch?v=_TtHrgR9GNg\"><em>Zone Hunter<\/em><\/a>. I was immediately hooked and I knew I wanted to work in VR! I started my <a href=\"http:\/\/cb.nowan.net\/blog\/about-me\/\">VR career<\/a> more than 12 years ago working on industrial VR training applications and VR software tools.<\/p>\n<p>I am now the founder and president of a company called &#8220;<a href=\"http:\/\/www.imin-vr.com\">i&#8217;m in VR<\/a>&#8220;. We offer tools to simplify the creation of VR applications such as <a href=\"http:\/\/www.imin-vr.com\/middlevr-for-unity\">MiddleVR<\/a>, a VR middleware that enables 3D applications (like <a href=\"http:\/\/www.unity3D.com\">Unity<\/a>) to run on any VR system (HMD, caves etc.). I&#8217;ve been <a href=\"http:\/\/cb.nowan.net\/blog\/\">blogging<\/a> about VR long before it was cool, and you can also find me on twitter (<a href=\"https:\/\/twitter.com\/Cb_VRGeek\">@Cb_VRGeek<\/a>)<\/p>\n<p><!--more--><\/p>\n<p>Now, you may think creating VR applications is easy: simply add  camera rotations using the Oculus Rift tracker and you&#8217;re done. This can  work for some applications, but it will fail for the vast majority of  them.<\/p>\n<p>VR is all about <strong>presence<\/strong> in a virtual world. If you can&#8217;t <strong>keep<\/strong> your player immersed into it, you&#8217;re not doing it right. You can trick  your brain into thinking it is in another reality, but this is more  difficult than it sounds. This feeling of presence is very fragile.<\/p>\n<p>Articles dealing with VR often adopt a too technical approach. I  think VR is first about what&#8217;s happening in the user&#8217;s mind. In this  article I am going to focus on some fundamental points about this  presence in another world and why it is important to design your  application for this goal.<\/p>\n<h1>VR in 2013<\/h1>\n<p>Virtual reality allows you to <a href=\"http:\/\/cb.nowan.net\/blog\/2012\/11\/17\/an-introduction-to-immersive-virtual-reality-update\/\">immerse people in a 3D environment<\/a>, with head-mounted displays (HMDs or VR goggles), or <a href=\"http:\/\/cb.nowan.net\/blog\/state-of-vr\/state-of-vr-displays\/\">other immersive systems<\/a>. That&#8217;s why we often call it immersive VR (iVR) &#8212; to differentiate it from virtual worlds like <em>Second Life<\/em> or <em>World of Warcraft<\/em>. VR was hyped in the early &#8217;90s, but failed to deliver the experience the public expected.<\/p>\n<p>However, it continued to evolve on the serious games side, to a point where it is now <a href=\"http:\/\/cb.nowan.net\/blog\/state-of-vr\/state-of-vr-application\/\">an essential tool for several markets<\/a>:<\/p>\n<ul>\n<li><strong>Training<\/strong> in VR can be much more efficient than in  real life: you can control the training environment very precisely, view  replays, and actually safely practice real gestures in many different,  potentially dangerous, scenarios. This is used for training surgeons,  soldiers, policemen, firefighters, dentists and even workers applying  coatings on houses! This allows companies to save expensive materials  while delivering better feedback about gestures.<\/li>\n<\/ul>\n<ul>\n<li>All major car manufacturers have their VR systems where they can test <strong>designs and ergonomics<\/strong> of products that don&#8217;t yet exist, and iterate very quickly compared to a  physical mock-up. This is now also applied for planes, boats, tractors,  production lines, factories, and even kitchens! See the VR applications  and systems from <a href=\"http:\/\/youtu.be\/pBuNHqJrHHk\">Peugeot<\/a> or <a href=\"http:\/\/cb.nowan.net\/blog\/2010\/10\/12\/more-about-fords-vr-facilities\/\">Ford<\/a>.<\/li>\n<\/ul>\n<ul>\n<li><strong>Communicating<\/strong> around a digital mock-up is very  natural: you can get immersed in your future building, or live urban  planning years before modifications. See this <a href=\"http:\/\/www.youtube.com\/watch?v=EySdWbR4qcg\">Enodo demo reel<\/a>.<\/li>\n<\/ul>\n<ul>\n<li>It is also a great tool for <strong>market research<\/strong> for the <a href=\"http:\/\/www.theaustralian.com.au\/archive\/business-old\/virtual-reality-takes-shoppers-to-another-world\/story-e6frg90x-1111112380446\">retail industry<\/a>:  you get a real feeling of your shop before it is built or rearranged.  You can track all the customer&#8217;s movements and record where they look.  This is useful to test the layout of furniture or make sure that the  design of your product is visible among other products.<\/li>\n<\/ul>\n<ul>\n<li><strong>Treating phobias<\/strong> in VR is an efficient method: if  you&#8217;re subject to a fear of heights, we can create a virtual cliff and  you will actually experience your phobia. Then a real therapist can help  you dealing with it more efficiently than going to a real cliff. The  same applies for fear of taking the plane, fear of spiders, dogs, and  speaking in public for example. See the <a href=\"http:\/\/w3.uqo.ca\/cyberpsy\/en\/index_en.htm\">Cyberpsychology lab<\/a> from St\u00c3\u00a9phane Bouchard.<\/li>\n<\/ul>\n<p>And, of course, VR can be used for games! But since the mid-&#8217;90s,  very few games have been created with this technology; most were  developed at research labs or by enthusiasts. Doing so required the  skills and hardware to assemble a VR system and program the game  themselves. To my knowledge, no commercial VR game has been created in  the past 10 years.<\/p>\n<p>Here&#8217;s an <a href=\"http:\/\/www.vrgeeks.org\/wiki\/vr-games\">on-going list<\/a> of pre-Oculus VR games. But now, thanks to the arrival of the Oculus  Rift, everyday is Christmas! We&#8217;re just starting to see new VR games and  experiences (like the <a href=\"http:\/\/vimeo.com\/65510054\">virtual guillotine<\/a>).<\/p>\n<hr \/>\n<h1>Why (Not) Create a VR Game?<\/h1>\n<p>The first question to ask is whether your game would be relevant in  VR. It&#8217;s like with 3D. Not everything is interesting in 3D, and if it is  not appropriate it can get worse in VR!<\/p>\n<p>So why go VR?<\/p>\n<p>The objective of VR is that you feel like you&#8217;re <strong>present<\/strong> in another reality, whether it is realistic or not. For me, presence is the definition of VR. <strong>Without presence, there is no VR!<\/strong><\/p>\n<p>Obvious game genres that would be great in VR are all the first-person games, like first-person shooters. Imagine <em>Mirror&#8217;s edge<\/em> or <em>Call of Duty<\/em> as VR games! Some third person games like <em>Assassin&#8217;s Creed<\/em>, <em>Splinter Cell<\/em>, or <em>Gears of War<\/em> could potentially be converted to first-person, so we can actually <strong>be<\/strong> the hero. Of course, I&#8217;m sure we will see a revival of puzzle and  exploration games. We will also probably see very different VR games in  the future: God games? <em>Guitar Hero<\/em>?<\/p>\n<p>But I think the games that will benefit the most from VR are those that try to <strong>generate emotions<\/strong> in the player.<\/p>\n<p>Survival horror games would be extremely intense. Also take <a href=\"http:\/\/www.heavyrainps3.com\/\"><em>Heavy Rain<\/em><\/a>,  for instance. The game is great; I felt really present, and I  experienced a lot of emotions while playing it. However, the game was  sometimes ruined by non-natural interaction, and lacked half the  presence &#8212; the physical presence. And this is where VR can help!<\/p>\n<h1>VR as a New Medium<\/h1>\n<p>I should say a word of warning here before continuing: adapting  existing games to VR is difficult if they weren&#8217;t designed for this from  the outset. VR is like radio or TV at their beginnings: radio was only  used to broadcast opera, and TV was only used to broadcast theatre  plays. Slowly, people started to create content specifically tailored  for these new media. Camera movement, zoom, and cuts created a new  grammar for film, for instance.<\/p>\n<p>The same will happen with VR! At first, there will be a lot of  adaptations of existing games that don&#8217;t take full advantage of  presence, and might even damage the field: adding VR will only  marginally improve immersion, thanks to the display, but awkward  controls and gameplay unsuited to VR could potentially make the  experience poorer than it originally was.<\/p>\n<p>I&#8217;m happy to see that a lot of indie developers are creating new  games with VR in mind from the beginning, which is the right way to do  it. And why wouldn&#8217;t they? VR is the ultimate experience! Those of us  with experience we will happily provide feedback for your game, so don&#8217;t  hesitate to <a href=\"http:\/\/cb.nowan.net\/blog\/about-me\/\">contact me<\/a>.<\/p>\n<h1>Presence<\/h1>\n<p>As I said, <strong>presence is, for me, what defines VR<\/strong>.  Without this feeling of actually being somewhere else, your system is  just an interactive 3D system, not a true VR system &#8212; even if it costs  millions of dollars. Trust me, I&#8217;ve tested a few of those, and it&#8217;s a  tragedy.<\/p>\n<p>Once you get presence, your player will experience <strong>natural reactions and emotions<\/strong>:  if you&#8217;re on top of a high cliff, you will experience the fear of  heights (guaranteed). If a virtual ball is thrown at you, you will try  to catch it. If an avatar saves you from certain death, you might  actually smile at him. <a href=\"http:\/\/cb.nowan.net\/blog\/2007\/04\/23\/laval-virtual-2007\/#more-330\">True story<\/a>!<\/p>\n<p>Presence is a complex and subtle topic. <a href=\"http:\/\/melslater.eventlab-ub.org\/\">Mel Slater<\/a> is one of the scientists conducting some of the most interesting research on presence. In a well-known <a href=\"http:\/\/cb.nowan.net\/blog\/2009\/09\/18\/immersion-place-illusion-and-plausibility\/\">article<\/a>, he splits presence in two: <strong>cognitive <\/strong>(mind)<strong> <\/strong>and<strong> perceptive <\/strong>(senses).<\/p>\n<p>Most people report presence when playing a game, watching a movie,  reading a book, or just hearing a story (the roots of VR!). This is  actually <strong>cognitive presence<\/strong> &#8212; where their mind takes them to another world.<\/p>\n<h1>Perceptive Presence<\/h1>\n<p>All of these experiences lack <strong>perceptive presence<\/strong>, which is in fact <strong>fooling your senses <\/strong>in a realistic way. Vision, but also sound, touch, smell, <a href=\"http:\/\/en.wikipedia.org\/wiki\/Proprioception\">proprioception<\/a>&#8230;  Keep in mind that humans are not able to perceive the world perfectly:  the human brain makes all sorts of simplifications. Knowing the limits  of human perception, which is a fundamental part of understanding VR,  allows you to create <a href=\"http:\/\/cb.nowan.net\/blog\/2010\/03\/29\/ieee-vr-2010-perceptive-illusions\/\">perceptive illusions<\/a>, such as <a href=\"http:\/\/cb.nowan.net\/blog\/2008\/12\/02\/redirected-walking-playing-with-your-perceptions-limits\/\">redirected walking<\/a> or <a href=\"http:\/\/on.aol.com\/video\/virtual-reality--from-headsets-to-handhelds-517341756\">impossible spaces<\/a>.<\/p>\n<p>So how do you achieve that?<\/p>\n<p>For me, the most basic way of creating perceptive presence is by  using head tracking. Moving your head and, as a result of this movement,  seeing the world from a different viewpoint, is the basis for the  action\/perception loop.<\/p>\n<p>So you need to be able to move, and those moves must have an effect on the virtual world. Your body is engaged: as <a href=\"http:\/\/en.wikipedia.org\/wiki\/Antonio_Damasio\">Antonio Damasio<\/a> says, &#8220;the mind is embodied, not just embrained.&#8221;<\/p>\n<h1>Breaks in Presence<\/h1>\n<p>This also means that if, as a result of your actions, you&#8217;re not  getting the result that you&#8217;re expecting your brain will know something  is wrong. This is called a &#8220;<strong>break in presence<\/strong>&#8221; (BIP).<\/p>\n<p><strong>If you have only one goal<\/strong> when creating a VR game, it would be to <strong>create and maintain presence<\/strong>. Feeling present in an empty room is VR. Not feeling present in <em>Gears of War<\/em> is not VR.<\/p>\n<hr \/>\n<h1>Minimal VR system<\/h1>\n<p>My recommendation would be to support head tracking (rotations +  translations), tracking of at least one hand (rotations + translations),  and a joystick with a couple of buttons. From my personal experience,  when you have this minimum setup, you cross a threshold, and your brain  much more easily accepts this other reality.<\/p>\n<p>This means that, for me, the Oculus Rift by itself is not (yet) a  minimum VR platform. It&#8217;s missing head position tracking and doesn&#8217;t  provide any kind of hand tracking. I know you can easily add it yourself  with devices such as the <a href=\"http:\/\/www.razerzone.com\/gaming-controllers\/razer-hydra\">Razer Hydra<\/a> or others. But unless we have a complete VR platform, game developers  can&#8217;t rely on the fact that players all have the same standard hardware.<\/p>\n<h1>Latency<\/h1>\n<p>The first enemy of VR is latency. If you move your head in the real  world and the resulting image takes one second to appear, your brain  will not accept that this image is related to the head movement.  Moreover as a result, you will probably get sick. John Carmack reports  that &#8220;something magical happens when your lag is less than 20  milliseconds: the world looks stable!&#8221;<\/p>\n<p>Some researchers even advise a 4ms end-to-end latency from the moment  you act to the moment the resulting image is displayed. To give you an  idea of what this means, when your game runs at 60 frames per second  it&#8217;s 16ms from one frame to another. Add to that the latency of your  input device, which can range from a few milliseconds to more than 100ms  with the Kinect, and the latency of the display, which also ranges from  a few milliseconds to more than 50ms for some consumer HMDs.<\/p>\n<p>And if you want to run your game in stereoscopy, keep in mind that  the game needs to compute the left and right images for each frame. As a  game developer, you can&#8217;t do much for the input and display latency,  but you have to <strong>make sure that your game runs fast<\/strong>!<\/p>\n<p>For more information about latency, I recommend these great articles by Michael Abrash and John Carmack (my personal heroes): &#8220;<a href=\"http:\/\/blogs.valvesoftware.com\/abrash\/latency-the-sine-qua-non-of-ar-and-vr\/\">Latency, the sine qua non of AR and VR<\/a>&#8221; and &#8220;<a href=\"http:\/\/www.altdevblogaday.com\/2013\/02\/22\/latency-mitigation-strategies\/\">Latency mitigation strategies<\/a>.&#8221;<\/p>\n<h1>A Coherent World, Not Necessarily a Realistic One<\/h1>\n<p>We have seen that perceptive presence requires you to fool your  senses in the most realistic way. Cognitive presence &#8212; fooling the  mind, not the senses &#8212; results from a sense that your actions have  effects on the virtual environment<strong>, <\/strong>and that these events are credible. This means that you must believe in the &#8220;rules&#8221; of the simulation. For this, you must <strong>make sure that your world is coherent<\/strong>,  not necessarily realistic. If a player can grab a particular glass, for  example, but can&#8217;t grab another one, it will break presence because the  rules are not consistent. Once cognitive presence is broken, it&#8217;s very  difficult to &#8220;fix&#8221; it. The player is constantly reminded that the  simulation is not real, and it will take some time to accept it again as  reality.<\/p>\n<p>If you&#8217;re targeting a visually realistic environment, it is more  likely to generate breaks in presence. This is because your brain will  expect many things that we are not yet able to achieve technically:  perfect physics, sound, force feedback so that your hand doesn&#8217;t  penetrate an object, objects breaking in pieces, smell, etc. Having a  non-realistic environment will lower your expectations that everything  should be perfect, resulting in a more consistent presence feeling.<\/p>\n<p>If you manage to achieve cognitive presence,\u00c2\u00a0 and fool the mind of your player, the events from the simulation <strong>will affect his sensations<\/strong>. If an attractive character looks at a shy guy into the eyes, his heart rate might increase, he will blush, etc. <a href=\"http:\/\/portal.acm.org\/citation.cfm?id=641638\">People with a fear of public speaking will react with anxiety if speaking to a virtual audience<\/a>.<\/p>\n<p>This is why the application I still find the most immersive is &#8220;<a href=\"http:\/\/www.youtube.com\/watch?v=ZBfYIefenp0\"><em>Verdun 1916-Time Machine<\/em><\/a>.&#8221;  It fools many senses at a time: vision, smell, touch&#8230; But the most  important point is that, by design of the &#8220;experience,&#8221; the interactions  are extremely simple: you can only rotate your head, because you&#8217;re a  wounded soldier.<\/p>\n<p>Given that extreme limitation, it&#8217;s extremely simple to keep the  player from experiencing a break in presence. You can&#8217;t move your hand,  so it cannot penetrate objects; you aren&#8217;t forced to navigate with an  unnatural joystick. It has been reported several times that some people  smiled at another virtual soldier that came to save the player in the  simulation!<\/p>\n<h1>Measure Presence<\/h1>\n<p>The problem is that it&#8217;s very difficult to concretely measure whether  a player feels present in the world. There are currently no absolute  indicators for that. You can measure the heart rate or skin conductance  if you want to evaluate anxiety. But this is only relevant for stressful  simulations.<\/p>\n<p>What you can try to evaluate though is if the player is responding  naturally. We already mentioned a few natural reactions: trying to catch  a ball, fear of heights near a cliff, fear for your virtual body if  somebody is trying to hurt you, trying to avoid collisions&#8230;<\/p>\n<hr \/>\n<h1>Tips for VR Games<\/h1>\n<p>Enough with the philosophical considerations, for now. Here are a few practical tips:<\/p>\n<p><strong>Scale 1<\/strong>. The scale of the world has to be realistic.  You should feel like you are the right height (unless you want your  player to be a child, as in <em><a href=\"http:\/\/www.kickstarter.com\/projects\/krillbite\/among-the-sleep\">Among the Sleep<\/a><\/em>). Head movements should not be amplified (unless you&#8217;re using <a href=\"http:\/\/cb.nowan.net\/blog\/2008\/12\/02\/redirected-walking-playing-with-your-perceptions-limits\/\">redirecting techniques<\/a>).<\/p>\n<p>The easiest way to achieve Scale 1 is to make sure that 1 world unit  is 1 meter. The field of view should exactly match the field of view of  your HMD. In an ideal world (or big industrial VR system) the distance  between your two eyes should also be correctly measured and used. Your  brain picks up all these cues; you might not be able to create or  maintain presence &#8212; and even make people feel sick! &#8212; if you don&#8217;t  strictly follow this rule.<\/p>\n<p><strong>Know your hardware<\/strong>. Know the <strong>range of tracking<\/strong>:  Can my hardware track translations, or only rotations? If the tracker  also reports positions, up until what distance? What&#8217;s its <strong>precision<\/strong>? When does the tracking data stop being usable? Know the <strong>field of view<\/strong>:  As you are supposed to follow the &#8220;Scale 1&#8221; rule, you shouldn&#8217;t distort  the virtual field. If the field of view is narrow, the user will have  to move her head much more to see around than with a bigger field of  view, and might miss some important action in the periphery. Know the <strong>resolution<\/strong>:  if you want the user to read information, she will have to come much  closer with a low-resolution display than with a high-resolution  display. As with Android development, your game might end up running on  different hardware. We will soon have a HMD war with lots of HMDs, each  with different characteristics. Using tools like <a href=\"http:\/\/www.imin-vr.com\/\">MiddleVR<\/a> will help you work with many different VR systems.<\/p>\n<p>Have a <strong>consistent viewpoint<\/strong>. If your game is a first  person game, avoid playing cinematics or making the player drive a  vehicle from a third person view. It breaks immersion.<\/p>\n<p><strong>Break habits<\/strong>. Longtime video game players have bad  habits: when they wear an HMD they will stand still, as if they&#8217;re  seated in front of a TV. Those who are less experienced with games  people will naturally look around. Gamers need to <em>unlearn<\/em> the  constraints of current games. In a tutorial, you should force the user  to look around and move his hands. Your game should also take advantage  of those new possibilities. For example, in a recent game prototype I  worked on, we had enemies appearing to the right, left and above the  player; there is no joystick\/mouse to navigate and look around. It  forces the user to look around and aim with his hand to get all the  enemies. In another game prototype I worked on, the only interactive  object is a candle in a very dark environment. This was a great way to  force the player to explore: he naturally took the candle, and used it  to explore the dark environment, pushed some objects, and burned others  to solve the puzzles.<\/p>\n<p><strong>Try to keep the player active.<\/strong> In <em>Heavy Rain,<\/em> for example, you&#8217;re almost always playing. There are numerous cutscenes  that look like videos, but suddenly you&#8217;ll have to perform an action.  If you don&#8217;t have the game controller in your hands at this moment,  you&#8217;ll fail the action. This forces you to always be alert and ready.<\/p>\n<p>Another very interesting feature of <em>Heavy Rain<\/em> is that <strong>the game happens in real-time,<\/strong> which means you sometimes have to take decisions and act fast: do I  have to shoot this guy before he kills my partner? You&#8217;re forced to act  quickly &#8212; and as in real life, once you make a decision, you&#8217;ll never  know if it was right or not.<\/p>\n<p><strong>Create realistic puzzles.<\/strong> Still another example from <em>Heavy Rain<\/em>:  You&#8217;re in a rush and have to phone a room in a motel. Can you remember,  in less than 15 seconds, the room number? Just as in real life, you  have to dig it from your memory while experiencing a lot of stress.<\/p>\n<p>Finally, <strong>work hard on presence<\/strong>. Presence is not easy  to build. Start light, test often. Build presence slowly, make small  additions, test again. The experience is what happens in the user&#8217;s  brain! Your simulation enables the experience: it is not the experience!  Presence should be natural. Observe the reactions and modify the game.  Don&#8217;t throw in every possible gimmick just because it will make a cool  video. A lot cool videos really end up being terrible experiences.<\/p>\n<h1>Conclusion<\/h1>\n<p>There is of course a lot more to be said about developing a VR  application, but I hope this article got your attention on some  fundamental points. I leave you with this quote that I hope you will  apply:<\/p>\n<p><em>&#8220;Our approach is to treat virtual  reality as something quite new with its own unique conventions and  possibilities that provide a media where people respond with their whole  bodies, treating what they perceive as real.&#8221;<\/em> &#8211; Mel Slater<\/p>\n","protected":false},"excerpt":{"rendered":"<p>[This is a re-post of the original Gamasutra article which was published on May 23, 2013] When I was on a field trip to London back in high school, I played my first virtual reality (VR) game: Zone&#8230; <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7,9],"tags":[],"_links":{"self":[{"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/posts\/1642"}],"collection":[{"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/comments?post=1642"}],"version-history":[{"count":3,"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/posts\/1642\/revisions"}],"predecessor-version":[{"id":1652,"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/posts\/1642\/revisions\/1652"}],"wp:attachment":[{"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/media?parent=1642"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/categories?post=1642"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/cb.nowan.net\/blog\/wp-json\/wp\/v2\/tags?post=1642"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}