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Vorontsov

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    Vorontsov reacted to will2k for an article, Optimizing An Open Map in Source Engine   
    An open map?
    Source engine, which is funnily a Quake engine on steroids (a bit of exaggeration but still), inherited the same limitations of its parents in terms of visibility calculations: BSP and PVS. This fact makes Source, as was Quake engine before, more suitable to rooms and hallways separated by portals where the BSP shines in all its glory.
    Inheritably, Source does not like large open maps where the PVS is of considerable size and the over-rendering is a real issue.
    If you work with Source engine, then you already know the importance of optimization in a large, detailed map. Optimization becomes even more imperative when the said map is open.
    What’s an open map? Good question. The word “open” is an umbrella term to denote any map that does not have traditional hallways and corridors that connect indoors to outdoors. The map is mostly large, outdoors with an unbroken skyline; in other words, the same stuff that source engine nightmares are made of in terms of PVS and BSP.
    In a traditional “hallway’d” map with twisted corridors leading to open areas followed by other hallways, and even if you “forgot” to place hints and areaportals, the geometry itself allows the engine to cut visleaves and limit visibility; granted the visleaves’ cuts will be subpar and messy and the PVS will be in excess, but still, the visibility and fps will be relatively under control. A twisted hallway is a remedy to long sight lines after all.
    In an open map, and without hallways and enough geometry to help the engine, the PVS risks to be huge and the whole map could be rendered at once from any point (over-rendering). We are talking here about a severe fps killer and a potential slideshow on a medium to low range computer. Source does not like over-rendering; I repeat, Source does not like over-rendering.
    I believe a screenshot should be welcome at this stage to illustrate an open map. I’ve chosen a nice medium-size map from CSGO to showcase the issue: de_stmarc.

    The shot is taken in Hammer obviously, and you can immediately see that the skybox is one big unbroken body from one edge of the map to the opposite one. This is the classic definition of open map.
    Let’s see this map in 2D view from the side.

    I have highlighted the skybox in blue so you could see the continuous sky body all over the map. Please note that an open map can have varying skybox shapes but I’ve chosen the simple and classic one to showcase my point where it is easier to see and visualize the concept of open map.
    In contrast, a “traditional” map will have several skyboxes, often not connected directly but rather through a system of indoor rooms or hallways, varying in size and shape.
    I will have my map de_forlorn as example here.

    I have also highlighted the skybox in blue and you can easily notice several skyboxes for CT spawn, T spawn, and Mid/bombsites. These skyboxes are not directly connected to each other but the areas related to them are linked on the lower levels through various indoor locations, some vast (like garage, tunnels…) and some small (like lab hallway…).
    If you are not that comfortable with source optimization or feel that certain terms are alien to you, then please read my previous optimization papers and articles before proceeding further in this article (Previous papers can be found here Source Engine Optimization roadmap).
    The necessary tools
    I’m not revealing a secret when I tell you that the same tools used to optimize any map in Source are exactly the same ones used for optimizing an open map. If you were expecting some magical additional tools, I’m sorry to bust your bubble.
    Since the tools are the same (nodraw, func_detail, props, hints, areaportals, occluders…), it is more about how to use them in open maps that makes all the difference.
    So, how to properly optimize an open map? Well, you could always pay me to do so for you (joking…not…maybe…I dunno!!)
    If the above option is off the table, then read on the rest of this article .
    Horizontal hints
    While in a traditional map one might get away without using horizontal hints, it is virtually impossible to skip them (pun intended) in an open map unless you want to witness single digit fps burning your eyes on the screen. They are of utmost importance to negate the "tall visleaves across the map" issue.
    In a traditional map, even if you bypass adding horizontal hints, the damage in fps will mostly be local since the skyboxes are not connected and areas are mostly autonomous in terms of PVS. In case of my map “Forlorn” and referring to the 2D diagram above, if I remove horizontal hints from CT spawn, then only this area will suffer from tall visleaves and over-rendering. Obviously, this is not cool in terms of optimization, but at least the effect will be somehow restricted to this area only.
    In the case of “Stmarc”, you can certainly see that not including horizontal hints will have tall visleaves seen from across the map as the skybox is one unit. The PVS will grow exponentially and the over-rendering will take its toll on the engine.
    Let’s move on to some screenshots and diagrams, shall we.

    This is our glorious open map in side view. The blue lines denote the skybox, the dark grey one is the ground, and the green rectangles represent solid regular world brushes such as building bases for example. The red starfish little-man-with-arms-wide-open is the player. The orange hollow rectangles denote the various visleaves that the engine would probably create in the map (most go from ground level to skybox level and this is what I refer to as “tall visleaf”).
    If you know your optimization, then you certainly remember that BSP relies on “visibility from a region” approach (for a refresher, please consult my papers Demystifying Source Engine Visleaves and Source Engine PVS - A Closer Look. This simply translates to the following: the player is in visleaf A and visleaf A has direct line of sight to visleaves B, C, D, E, F, and G. The PVS for A in this case would be stored as BCDEFG. Once the engine recognizes that the player is in A, and regardless of the exact position in A, it will proceed to render the whole PVS content. Everything in visleaves BCDEFG will be rendered even though the player is at the extreme end of A and has no line of sight to most of this content.
    You can immediately notice the extent of damage you will inflict on your open map if you neglect adding horizontal hints: excess PVS with additional useless content to be rendered at all times.
    Now that we established the importance of these horizontal hints in open maps, the question remains: where shall I put these hints?
    In the diagram above, the most logical places would be on top of the 3 green rectangles.

    We added 3 horizontal hints (H1, H2, H3) on top of the 3 regular brushes in our map (the hint face neatly resting on the top of the regular brush while other faces are textured with “skip”). This will create more visleaves as can be clearly seen in the above diagram, and vvis will take more time to calculate visibility due to the increased number of leaves and portals but this is done for the greater good of humanity your map’s fps.
    Now the player is in visleaf A1 and the PVS is reduced to (sit tight in your chair) A2, A3, A4, B1, B2, C3, C4, D1, E4, F3. On top of the nice result of a greatly reduced PVS (and therefore content to render), keep in mind that leaves A4, B2, C4, D1, E4, and F3 are mostly empty since they are way up touching the skybox.
    Some folks will start complaining and whining: what the hell dude, I don’t have 3 green rectangles in my map; where would I put my hints?? My answer would be: deal with it!!
    Joking aside, open maps will greatly differ in size, shape, geometry, and layout. What you need to do is choose 1 to 5 common height locations in your map where you would implement these hints. Medium maps with mostly uniform building heights can get away with 1 horizontal hint, while complex, large maps with various building heights can do with 4-5 hints.
    If your map has a hill made of displacements that separates 2 parts of the map, then it is also a candidate for horizontal hints. You just need to insert a nodraw regular world brush inside the displacement to be used as support for the horizontal hint (the same technique can be used if you have a big non-enterable hollow building made mostly of func_detail/props/displacements).
    Vertical/corner hints
    These might not come into play as much as their horizontal siblings, however they could see a growing potential use depending on the map’s layout, geometry tightness versus openness.
    I cannot go through all combinations of open maps obviously to show you how to lay vertical and corner hints; what I will do is choose one diagram representing a typical open map scenario with some scattered houses, streets, and surrounding fields. Once you see how I proceed with these hints, it will become a lot easier for you to implement them in your own map regardless of the differing geometry and layout.

    Here’s our typical map viewed from top with grey lines being map borders, green rectangles being houses (solid world brushes), and our tiny red player at the rightmost part of the map. The map has a main street that goes in the middle between houses but the player is not restricted to this path only.
    The diagram below shows how I would proceed with my hints for such setup.

    This is basically what you get when you give a 5-year-old some crayons.
    Seriously though, I just gave each hint a different color so you could discern them on the spot, otherwise it would be hard to tell where each one starts and ends.
    Most of these hints go from one side of the map to the other while going from ground level to skybox top; don’t be afraid of having big hints that cross your entire map.
    Notice that we have both straight vertical hints (shown from above in the diagram obviously) and corner hints; what I did is that I compartmentalized the map so wherever the player is, chances are they will have the least amount of leaves to render in the PVS (this is just a basic hint system and more fine tuning and additions could be done but you get the gist of it).
    To get more details on hint placement, please refer to my paper Hints about Hints - Practical guide on hint brushes placement
    Areaportals
    If your map has enterable buildings, then it is imperative to separate indoors from outdoors using areaportals; this is top priority.
    Make sure to slap an areaportal on each door, doorway, cellar door, window, roof opening, chimney, etc. that leads inside the house in question.
    What about outdoor areaportals? Good call. In an open map without much regular world brushes to maneuver, it could get very tricky to set up an outdoor areaportal system to separate areas. However, you should always strive to have one, even if it is one or two areaportals across the map. The reason is very simple: the view frustum culling effect, which, coupled with hints, will yield the best results in cutting visibility around the map.
    Continuing with our previous diagram, a simple outdoor areaportal system setup could be as follows (top view).

    This setup will make sure that the map is split into 4 areas and whenever you are in one of them as player, the view frustum culling effect will kick in to cull as much detail as possible from the other areas.
    Let me show you the setup from a side view to make it easier to visualize.

    This is the same areaportal that was closest to the player in the top down view diagram but this time viewed from the side. Unlike hints where it’s fine to have one big hint going across the map, for areaportals, it is best to have several smaller ones that tightly follow the contour of the geometry eventually forming one big areaportal system.
    Another possibility for outdoor areaportal system is to have a combination of vertical and horizontal (yes horizontal) areaportals.
    If your map is a village for example with a highly detailed central square where most of the action takes place, a potential system could be made of several vertical areaportals that sit in every entrance to the square from adjacent streets, and a horizontal areaportal that “seals” the area and works as a “roof”.
    For a practical guide on areaportals placement, please check out my article Practical guide on areaportals placement
    Props fade distance
    This is a really, really important tool when optimizing large open maps. In case you got distracted while I was making the announcement, I’ll go again: props fading is definitely vital when tackling open maps optimization.
    What you need to do is to set an aggressive fade distance for all trivial props that do not contribute to gameplay. Players will look closely at how detailed your map is when they check it out solo on the first run; however, when the action starts and the round is underway, adrenaline, focus, and tunnel vision kick in, and all the details become a blur.
    During an intense firefight, players will not notice small props and details up close, let alone at a distance. We need to use this to our advantage to fade props thus releasing engine overhead; a faded prop is not rendered anymore and engine resources will be freed and allocated elsewhere.
    Your map geometry will dictate the proper fade distances, but as a rough guideline, small props could have a fade distance anywhere from 800 to 1200 units (flower pot on a window sill, small bucket at the back door, a bottle on the sidewalk…), while medium props could do with 1400-1800 range (a shrub, a power box on the wall, an antenna on the roof, wood plank, gutter pipe, fire hydrant…).
    Be very careful though not to prematurely fade critical props used for cover or game tactics (car in the middle of the street, sandbags, stack of crates, dumpster on the sidewalk…).
    Cheap assets
    Many people forget about this technique which is more than needed when it comes to open maps that tend to have larger average PVS than traditional maps.
    I showcased in a previous article of mine the fps cost of cheap and expensive assets (Source FPS Cost of Cheap and Expensive Assets).
    Get in the habit of using the low-poly model version as well as the cheap texture version in the distant non-playable areas and the high unreachable areas where players won’t have much of close contact with the environment. Potential candidates could include a distant field, the unreachable opposite bank of a river, a garden behind hedges/walls, high rooftops, the 3D sky…).
    Fog/Far-z clip plane
    This technique, when correctly used, can provide a big boost to your frame rate as parts of the world beyond the opaque fog won’t be rendered at all.
    For this technique to work properly, your map should have a foggy/rainy/stormy/dusty/hazy/night setting (use as applicable) where a fully opaque fog won’t appear out of place. Obviously, if your map takes place in a sunny and clear day, this technique won’t work much and it will look inappropriate.
    Using this is simple: For example, if your map is set in a rainy and foggy day, you just need to set the fog end distance while having its density set to 1. You will then set the far-z clip plane to something slightly higher than the maximum fog distance (if the fog end distance is 8000 units for example, the far-z could be set to 8200).
    3D skybox
    This is another good technique to reduce engine overhead and the cost of rendering.  
    It is true that the 3D sky is used to expand the limits of your level and decorate its surrounding, however, since it is built at 1/16 scale (and expanded in-game), it is also a nice way to decrease rendering costs. Use this to your own advantage and relocate assets in the non-playable areas with limited player interaction to the 3D sky.
    One thing to keep in mind though, the 3D sky’s visleaf is rendered at all times on top of the PVS in the playable area. Do not go overboard and make an extra complex, highly expensive 3D sky or you would be defeating the purpose of this optimization technique.
    Occluders
    You thought I forgot about occluders? Not a chance as these are the big guns when it comes to large open maps with little world brushes to use for other optimization techniques.
    Let’s clear one thing first; if your map is made mostly of brushwork and displacements with little to no props, then there is absolutely no need to resort to occluders as they’d be totally useless in this case. Only when the map is loaded with models and props in an open setup with little regular world brushes that occluders come to play in force.
    To place occluders, you would search for areas where these occluders could make the most impact (low fps, high traffic, props abundance) since they run in real time and are expensive, otherwise their cost would outweigh their benefit in terms of frame rate variation.
    Remember that occluders rely on the player’s position and field of view relative to the occluder to calculate what gets culled. You need to place them in a way to maximize the number of props to be culled behind them when the player stands in front of these occluders.
    Let’s see some examples.

    We go back to our famous top down diagram; the occluder is dark blue placed on the left wall of the large house while the little black stars represent various props and models. The 2 diagonal black lines denote the player’s FOV relative to the occluder. Anything behind the occluder and within the view frustum will be culled.
    That’s nice; we are able to cull 4 props but is it enough? It is not optimal as we can still do better. What if we move the occluder to the right wall of the house?

    Much better if you ask me. 5 additional props were added to the culling process meaning less overhead and fewer resources to render for the engine. That is why I said earlier it is all about maximizing the impact of the occluder by placing it in a way relative to the player’s position that maximizes the number of culled models.
    Here’s another example (still top down view).

    The player has moved to the middle of the central street, and beyond that L-shaped house is an open field with a lot of props scattered around. One way to implement occluders is as showcased in the above diagram. Notice how I arranged 2 perpendicular occluders along the walls for the maximum occlusion effect as all of these props in the field are not rendered from that player location.
    Another way to arrange occluders in this case would be diagonally across the L-shaped house (split into 2 or 3 occluders if needed to accommodate the nearby geometry; they can be floating without the need to seal an area).
    If you’re feeling brave enough (you should be after reaching this far in this article), you could also add an extra occluder along the wall of the house to the left of the L-shaped house to further enhance the view frustum occlusion effect and cover more props in the field.
    The most common places to add occluders in open maps include a displacement hill that separates parts of the map, a hedge that stands between a street and a field full of props, a floating wall between a house garden and the street, the walls of a large house, the walls of a tall building, a ceiling when it separates multiple levels…
    To read more about occluders placement and cost, please consult my article Practical guide on occluders placement
    In conclusion
    The foundation of optimization in Source engine will be the same whether it is a traditional map or an open one. You will heavily rely on func_detail, nodraw, displacement, props… to achieve your goals but it is the way you use these tools in an open map that makes all the difference.
    One might get away with being a bit sloppy with optimization in a traditional map, however, make no mistake that an open map won’t be any forgiving if you decide to skip a beat in your optimization system.
    Talking about different open maps and formulating varying optimization systems for them could fill articles; I hope this article has shed enough light on the open maps optimization approach to let you easily design a system for your own map.
  2. Like
    Vorontsov reacted to will2k for an article, Viability of Hostage Rescue Scenario in CS:GO   
    This level design article is about the past and the present of the hostage rescue mode in Counter-Strike. Showcasing the inherent issues that accompanied the scenario allowing the bomb/defuse mode to gain traction and popularity. This article will also present what can be done, level design wise, to remedy some of the shortfalls and allow the scenario to be viable.
    A historical background
    Counter-Strike officially started life in June 1999 with the release of beta 1, and it shipped with four maps, that’s right, four whole maps. They were all hostage rescue maps and the prefix used for these maps was cs_ as opposed to the standard deathmatch maps starting with dm_. This prefix was an abbreviation of the game’s name (Counter-Strike) which hints to this hostage-rescue scenario being the only one in the minds of Gooseman and Cliffe, the creators of CS, at the time of launch.
    Fast forward a couple of months, beta 4 rolled out in November 1999 bringing to the table a new scenario, bomb defuse. The new maps carried the prefix de_ and while one would think that the hostage rescue maps would be switched to hr_ prefix, they kept the same prefix which started to be referred to as the “Classic Scenario”. Counter-Strike was built on hostage rescue scenario.
    I started playing CS in beta 2 in August 1999 (I totally missed beta 1, screw me) and maps like Assault and Siege were all the rage at LAN parties. The nearest LAN/internet café was a 5-minute drive from my place, and LAN parties with friends used to be a blast full of shouting, cursing, bluffing, noob-trashing; the standard menu for a CS session. Good times.
    Siege, the oldest CS map (beta 1), and Assault (beta 1.1) were the epitome of the game. You had to dive in as a CT deep into the T stronghold to rescue the hostages and bring them back to safety. These maps were the most played on LANs and embodied the style of early CS gameplay. At the LAN place where I used to wage my virtual battles, Assault equaled CS, literally. A fun fact is that when Dust came out, I started a LAN session with this map and everyone in the room shouted at me: "What the hell is this? We wanna play CS!" For my friends, Assault was CS.
    However, those rosy days for hostage rescue began to turn into grim grey when folks started playing bomb defuse scenario and realized how…fun it was. A map like Dust almost single-handedly pushed the scenario into higher ground with its bright environment/textures, clear/wide paths and its ease of use and noob-friendliness. A year later, around Summer 2000, Counter-Strike was now equivalent to Dust for my friends.
    How did this happen? What went wrong?
    Inherent flaws of hostage rescue
    Hostage rescue is a very delicate and tough scenario for law enforcement operators in the real world. It puts the assailing team at a great disadvantage against heavily-armed barricaded hostage-takers who are probably using civilian hostages as human shields and as a bargaining chip for a later escape.
    As you can deduce, transferring this scenario as realistically as possible into the game will not fare well, and this disadvantage will carry on for the CT team. The problem is only exacerbated when you add the more or less “flawed” game mechanics to the scenario. This is exactly what went wrong with hostage rescue scenario in case you are still wondering about the rhetoric questions at the end of the historical background introduction. The popularity of cs_ scenario started dwindling and the rise of the bomb/defuse scenario only made things worse.
    Almost all the early cs_ maps featured a relatively tiny hostage zone/room having one entryway usually sealed with closed doors that the CT must open to get access inside. This room was typically located behind T spawn which made the area a camping ground and made camping that zone an obvious and rewarding tactic for Ts. The doors having to be manually opened with a loudening sound made things worse and negated any surprise or sneaky rush towards the hostages. A classic example is the hostage area and T spawn in cs_assault.

    I dare not think of how many Ts are camping behind those doors
    Another equally important camp fest occurred in the hostage rescue zone. Early designs made the rescue zone relatively small with one or two access paths that can be defended from one location. If the CT team manages to reach the hostages and rescue them, the Ts could easily fall back to the rescue zone to camp and patiently wait for the CTs to show up. The hostage rescue zone in cs_italy is a nice example to showcase how one T could camp in the southernmost spot in the zone allowing him to monitor both entryways, from market and from wine cellar, within the same field of view. CT slaughter was almost a guaranteed thing to happen.

    A CT will show up any second now; imminent slaughter commencing in ...3, 2, 1
    A third flaw was the hostages themselves. They were difficult to escort and protect and were easily stuck or left behind in various parts of the maps between their initial hostage zone and the final rescue zone. I lost count of how many times I rescued the hostages and ran as fast as I could to the rescue zone, reaching it with a big grin on my face only to turn around and find out that only one or two of the four hostages actually followed me; the others were randomly stuck on a ladder, door frame, window ledge, vent, chair, table…I could go on but my blood is starting to boil just thinking of this.
    To add insult to injury, hostages could also be killed or “stolen” for ultimate trolling. When Ts were stacked on money, they could easily kill all the hostages, basically turning the round to a frustrating terrorist hunt for CTs. In early CS versions, a CT teammate could press the “use” key on a hostage that you were already escorting to steal it. This would leave you helplessly wondering where the hell did the 4th hostage go in case you did not catch the teammate performing the action.
    Lastly, maps themselves contributed to the issues that were piling up against hostage rescue scenario. If you are a CS veteran and you were around the early betas in 1999, you would most certainly remember how quickly hostage rescue maps were pruned from one beta to another; some maps even had a life span of 1 week before being discarded out of the official roster. Most of these early cs maps featured dark, nightly environments that were unfriendly to both newcomers and established players. Other maps had a confusing-as-hell labyrinthine layout that confused even the most great-sense-of-direction players, and made remembering paths nigh impossible. Some of these maps had narrow twisted paths and choke points, vents, and ladders that not only frustrated players (especially CTs) but also made rescuing and escorting the hostages more of wishful thinking. The icing on the cake was the different gimmicks introduced in some maps that made a frustrating gameplay/layout even more annoying: some maps had a machine gun nest in T spawn allowing Ts to master and perfect the art of CT slaughtering while other maps had flammable drums that could be shot and blasted for the ultimate carnage right next to the hostage zone. Good example maps include cs_prison, cs_bunker, cs_iraq, cs_hideout, cs_facility, cs_desert, among many others.
    Meanwhile, bomb/defuse scenario was gaining grounds at an increased rate and before too long, hostage rescue was relegated to a distant second place in terms of popularity among players and level designers alike.
    As a small experiment, I tallied the number of custom hostage and defuse maps submitted on Gamebanana for Counter-Strike Source and Global Offensive. For CS:GO, there are 761 de_ maps against 157 hostage maps while for CS:S, the figures are 4060 de_ for 1244 cs_ maps. The disparity is rather meaningful as the ratio in CS:GO is 4.85:1 while for CS:S the number is 3.26:1. This means that for each hostage map in CS:GO there are almost five maps of bomb/defuse whereas this number drops slightly to almost three maps for CS:S. With CS:GO putting extra focus on competitive gameplay, this ratio is bound to further grow widening the rift between bomb/defuse and hostage rescue maps.
    That’s it? Is it done for cs_ maps? Shall we prepare the obituary or is there a magical solution to breathe some fire and life in them?
    Solutions for viability
    There is a magical solution that involves you transferring a large sum of cash to my bank account, then my “guys” will contact your “guys” to deliver the “solution”. The drop point will be at the…apparently, there has been a mix-up, this is for another “deal” …nervous chuckle.
    Seriously though, while there is no magical solution that will lift hostage rescue onto the rainbow, there are a couple of things that level designers can do to start injecting some momentum to the scenario. Luckily for us, Valve has already paved the way (so these “Volvo pls fix pls” do work after all?). In March 2013, Valve introduced a major CS:GO update that completely overhauled the hostage rescue scenario mechanics and introduced cs_militia as well. The update was a game changer and a much needed tweak towards a better hostage rescue gamemode.
    We now have two hostages instead of four, and the CTs only need to rescue one of them to win the round. Moreover, the hostage does not stupidly follow the CT but instead is carried on the CT’s shoulders. Obviously the movement speed of the CT carrying the hostage is decreased but this “inconvenience” is countered with added bonus round time and the fact that the CT doesn’t have to glance over his shoulders every five seconds to make sure the hostages are still following him (this kind of distraction can prove fatal to the CT escorting the hostages). The hostages’ spawn location is randomized and can be controlled by the level designer. A nice change is that hostages don’t die anymore thus cutting any chance of Ts trolling (you still lose money when you shoot a hostage – shooting a hostage is pretty pointless now akin to shooting yourself in the foot).
    This is all good news if you ask me; hostage rescue is on the right path to become popular and viable again. With Valve doing the first half of the change, level designers have the duty to continue with the second half.
    Hostage defuse?
    As a first suggested solution, let us start treating hostage rescue as bomb defuse. Let’s be honest, bomb defuse works really well, so why not transfer this “experience” into hostage rescue. What we can do is to have a hostage rescue map’s layout mimic one of bomb defuse – that is have two hostage zones that are similarly placed as two bomb sites. We need to start treating a hostage zone like a bomb site with all accompanying techniques of rushing, pushing, faking, peeking, holding, smoking, flashing, etc. The good thing about this is that whatever knowledge, skill, and layout awareness that players have acquired from defuse scenarios will transfer effortlessly to the hostage rescue scenario; you do not need to learn new tactics and strategies. The roles will be inversed: instead of Ts rushing bomb sites and CTs defending, CTs will push hostage zones and Ts will defend and rotate.  
    Sounds logical, right? Some people might argue that having 2 separate hostage zones is not “realistic” and my answer is Counter-Strike was never about realism (carrying and running around with a 7 kg (15.5 lb), 1.2 m (47.2 inch) AWP sniper rifle with 25x telescopic sight, quickscoping and headshotting opponents is the epitome of “realism”). If you want a realistic hostage rescue scenario, then you are better off playing the original Rainbow Six Rogue Spear and SWAT 3 from 1999, or the more recent ARMA and Insurgency for a realistic military setting. I practice what I preach and I already implemented this technique in my last map “cs_calm”. The map was a remake of my CS 1.5 map from 2003 and obviously I made the “mistake” at that time to follow the trend set by official maps of having one hostage zone right behind T spawn. A playtest on Reddit CS:GO servers back in March 2015 confirmed that this setup won’t work well as Ts will inevitably abuse the hostage zone.
    I made some radical layout changes towards T spawn and hostage zone and created two new hostage zones on the upper and lower levels of the map that are connected by a back hallway to allow quick rotations (in addition to the one through T spawn). Obviously, there is no direct line of sight between hostage zones to prevent 1-zone camping. Ts have absolutely no incentive to camp one zone as CTs can reach the other one, rescue the hostage and head back to the rescue zone without being spotted from the other zone. CTs actually have a chance of winning the round by rescuing the hostages.
    I like to believe the new layout worked well. Only time and more hostage rescue maps will tell.

    Layout of the map "cs_calm"
    Rescue zone anti-camping
    We have remedied the hostage zone camping but we still need to tend to the rescue zone camping issue. A solution to this is to have two rescue zones in a similar setup to what is nicely done in cs_office. While Ts can still camp one zone, they risk a big chance of having CTs reach the other rescue zone. Again, CTs will have a viable option to save the hostages without being shredded by camping Ts. If the layout does not allow or facilitate having two rescue zones, then one big rescue zone with multiple entrances (three is a good number) should work fine. The trick here is to have the entrances not easily covered within the same field of view to prevent camping.
    Into the zone
    Just as we established that we should treat hostage zones like bomb sites, it goes without saying that each hostage zone should have at least 2 to 3 entry points. It’s pretty pointless to have only one entrance as this totally defeats the purpose of spreading hostages into two zones. The different entryways should also not be covered within the same field of view of one T; if a T decides to camp the zone, then he should be able to cover two entrances from one point leaving the third one more or less at a dead angle and viable for a CT rush or stealth/sneak surprise. 

    Showcase of Hostage Zone A on the map "cs_calm"
    The above screenshot showcases “Hostage Zone A” in cs_calm. A terrorist will typically camp near the hostage covering the two encircled entrances. The third entrance from upper level denoted by the arrow is not in the direct FOV, and is prone to a surprise attack by CTs that could catch the camping T off guard. If possible, try to spread the entrances on different vertical levels to spice things up and keep Ts on their toes.
    Lastly, it is a good idea to have a connector between hostage zones to allow fast rotations but without having a direct line of sight between hostage zones. We want to make the scenario fairer to CTs but not at the expense of Ts, inadvertently making it unfair for them.
    Conclusion
    Hostage rescue is a fun scenario if you ask me. It had many inherited and added flaws that contributed to its waning but it’s nothing that can’t be reversed. We, as level designers, need to push some changes to put the scenario back on track. What I just showcased in this article might not be the only viable solutions but they certainly are a step in the right direction. Level designers are intimidated by players who shun away from cs_ maps, and this turns into a vicious circle where players avoid hostage rescue maps and mappers in return avoid designing them. We need to break this cycle and designers need to bravely embrace the solutions I presented here or come up with their own solutions. The more cs_ maps that come out and get tested, the more we could validate these solutions as viable.
    In either case, we need to get proactive towards hostage rescue scenario; after all, this is the cornerstone that Counter-Strike was built upon.
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    Vorontsov reacted to Rick_D for an article, Making Agency, the popular CS:GO map   
    What is Agency?
    Just in case you have never heard of Counter Strike: Global Offensive, it's a hugely popular online FPS, successor to Counter Strike: Source and the original Counter Strike. The original came out in 1999 and the core gameplay has remained almost unchanged. Players are split into two teams and challenge each other in various game modes such as Bomb Defusal (one team has to plant and detonate the bomb while the other tries to stop them) and Hostage Rescue (one team must rescue the hostages whilst the other attempts to prevent that). The Bomb Defusal mode is by far the most popular, with maps designed with such detail that players can predict down to the second when another player is due to arrive in a certain area of the level. It's also the only mode played in competitive events and for huge prize money.
    This leaves the poor Hostage Rescue mode sitting on the sidelines twiddling it's thumbs and feeling a little rejected. In part this is because the Hostage Rescue mode is far more of a roleplaying experience, often with very poor odds of success for the team tasked with doing the rescuing. Often the levels are designed in such a way that the defending team has a large positional advantage, where simply staying-put will give them a good chance of winning.
    That's where we can start talking about Agency. Agency is a Hostage Rescue level, created as a collaboration between level designer Patrick Murphy, and myself doing the art. The basic idea being that Hostage Rescue could be just as precise and exciting as Bomb Defusal. It's been included in three official releases from the games creator, Valve, as part of their community level packs: Operation Bravo, Operation Phoenix and Operation Bloodhound. Phoenix being a community-voted choice, which was especially great to see that players enjoyed the style of gameplay and visuals that Agency brought with it.
    In this article I will go over the process of creating the art, from props to set dressing, texture creation and lighting, while maintaining a visually pleasing aesthetic and serving to enhance the gameplay. This isn't a postmortem but rather a walk-through of the various stages, hopefully to give some ideas to others, with lessons learned both positive and negative.

    Iteration from Whitebox to Final
    Starting out you should always have an idea of what you're going to create, even if it is quite vague, as it'll point you in the right direction for both creating architectural spaces and letting your imagination fill in the blanks as you build the basic shapes of the level. We knew we were going to build an office space, but style was leaning towards an older government building with red bricks and musty wood. As I started to put in some basic textures we decided it felt too bland, and similar to other levels in the game. In order to stand out and create something really interesting and intriguing that would entice players to want to explore the level we decided to modernize the space and use white as the primary colour - this would help players see each other more easily and provide a striking visual setting it apart from other levels.
    "Modern Office" is not exactly a style that has a single look, if you search for images you'll get back a lot of contrasting designs and ideas, trying to put every single one of those into a level would create a visual mess with no consistency. It's important to choose the right references for what you are building, something that looks cool in a single image or from a specific location might not fit into the theme of the level, and in a worst-case-scenario it might actually start to detract from the level as a whole. Trying to cram in as much content as possible simply makes your level feel less unified and jarring.
    Unfortunately when you are presented with so many fantastic designs and ideas it can be hard to pick out what is important. After settling on the location: a modern advertising agency's office, I broke down the needs of the level into a few different categories:
    Area Specific General Use Overall Theme The Area Specific content is "hero assets" for each location in the level. These are the things that help the player tell different areas apart from each other, a reception desk, a kitchen, a bathroom, etc. Assets that won't be used anywhere else except in their specific location.
     

    Examples of Area Specific Content

    The General Use content is the backbone of the building, it's wall sockets, ventilation tubes, sprinklers, desks and chairs. The things that could be used anywhere and would blend in to the background and not stand out unless you were specifically looking for them.
     

    Examples of General Use Content

    The Overall Theme content is what sells the theme of the level to players, advertising boards, company logos, large art installations and so on. These can be used everywhere but sparingly and should only be used as a subtle reminder to the player of where they are thematically. They shouldn't detract from the Area Specific content but should stand out more than the General Use content. This came in the form of abstract paintings, corporate logos, rotating advertisement panels and so on - things that would subtly tie the level together.
    Once these categories were laid out, searching through reference images became much simpler as you know what you need and only have to find an interesting design or detail that enhances a specific category.
    This isn't to say that everything was completely planned out or that development was flawless. Sticking to a plan only works until you open the editor, and if you try to force something you'll end up frustrated when it consistently fails to work. As an example we originally had the level set on the ground floor of a tall skyscraper. I spent a few weeks working on content for the ground but never really getting it to feel right within the theme of the level: the contrast between a dirty exterior street section and a spotless interior didn't feel right for the level, and felt a little too similar to another Counter Strike level. Patrick played around with some ideas and tried something I was afraid of: simply deleting everything I had done on the outside and adding an epic city vista. Instantly it felt right. The important thing to take away from this is that just because you have worked on something doesn't mean it's the right thing to be working on, and that getting input from other people with different ideas can vastly improve what you are working on.
     

    The first mockup of Agency's rooftop exterior
     

    The same space after an art pass

    Another incredibly important thing I realised is making use of modular assets. If you are going to duplicate something in your particular modelling software you should ask yourself: is this efficient? Chances are you're just making things harder to change later and locking yourself into a particular shape; eg: a walkway has a railing around it, you model the entire railing as a single object. Now if you need to change that walkway a month later you're going to have to go back and change your railing model. It's better to create a smaller tiling mesh that can be used multiple times, as often you'll find you can use that model in other areas and in different ways than you had initially intended. You're simply applying the concept of tiling textures to models, and in the process saving yourself a lot of time.

    A Believable Clean Art Style
    Creating a clean environment can often be more difficult and time consuming than a very dirty and cluttered one, simply because any mistakes are magnified by the lack of other objects to disguise them. A room with a single chair in the middle is going to end up with the focus being on that chair, if you fill that room with a hundred chairs you're going to be less concerned with the details of the chair and more worried about why someone would fill a room with a hundred chairs.
    In the modern office setting of Agency it would have made little sense to fill it with props and clutter, but a large empty space would just feel unfinished. A delicate balance of larger architectural shapes and smaller objects was needed. I like to think of this as functional art: it serves a purpose in the lore of the game world. Window and door frames, electrical sockets, thermostats and card swipes along with the maintenance apparatus of ventilation systems. These are the general use objects mentioned earlier, they fill out space and prevent an empty wall or ceiling from actually looking empty and at the same time they contribute to the believability of the level. It's important to think of the infrastructure of the building when placing these assets - if a wall has an air vent on it then the wall needs to be thick enough to support the ventilation pipes that feed it, Card swiping mechanisms need to be placed near doors at the correct height, electrical sockets should be placed logically in areas where they would be of use to the fictional inhabitants of the level and so on.
     

    Several examples of functional art details

    One of the most important things to do right when creating clean environments is to get the most out of the materials. It's not possible to cover every surface in dirt or decals, so the surfaces themselves become your way of showing detail.
    For Agency this was achieved by making liberal use of the phong shading techniques in the Source engine for models, and cubemaps for world textures. Almost all models in the level have some amount of phong shading, and although it doesn't produce a completely physically accurate result it can be used to create materials and surfaces that look relatively accurate. Simply by increasing or decreasing the intensity of the phong amount allowed for a vast majority of the levels surfaces to be rendered accurately. As I didn't need to have a lot of noisy detail in the materials due to the clean style I simply used a small phong texture as a mask for 75% of the models and let the lighting and general shapes of the models do the rest of the work.
     

    Simple phong shading to mimic real world materials

    As most of the surfaces had a single layer of material, ie paint or coloured metal, the phong shading could be completely even without breaking the illusion; however some of the dirtier surfaces such ventilation tubes and water pipes had several layers: a painted metal surface with area peeled away to reveal with metal underneath or a layer of dust. These had specific masks that would enhance the different materials, and showing wear and tear in the background assets added an extra layer of depth without compromising the clean style.
    Most of these textures were created with dDo, an excellent tool for quickly creating textures. I generally started with quite a dirty texture preset and toned down the details and noise until they were barely perceptible surface imperfections.
    Agency features probably close to 95% custom art, and that's a lot of work for a single person. Using dDo allowed me to make a lot of content relatively quickly, and kept it all visually consistent.
    The process of creating the assets with dDo was quite simple: first I modeled the basic ingame asset, then did a very quick and dirty placement of edge loops that allowed me to smooth the mesh and get a workable high poly. A very rough normal map was baked (along with a more solid ambient occlusion map), this rough normal map would never make it into the game, it was used purely for texturing with dDo. This rough-and-dirty technique was mostly used on the more general purpose assets that nobody would spend a lot of time looking at. For the objects that were in high traffic areas or that required finer detail a more robust normal map was created.
    Tiling textures used throughout the world were photo-sourced and tiled in Photoshop. A few examples worth pointing out are the plaster wall textures and the marble floors:
     


    The image above shows the ingame result, the diffuse texture, and the normal map of the standard plaster that is used throughout the level. The normal map was authored at 1024x1024 compared to the diffuse texture which was 512x512. I created several colour variations of the diffuse texture and for a very plain surface using a 1024x1024 diffuse didn't make much sense. The final touch was to add a subtle cubemap effect to bring out the normal map and add interesting coloured reflections in various areas.
     


    Another example is a marble floor used throughout the level. The normal map is unrealistic in that it portrays an uneven bumpy surface when in fact it is more likely to be uniformly flat. However to break up the reflections and add some visual interest to such a large and empty area I added a subtle bumpy normal map which warps the reflections, but is subtle enough that it doesn't get picked up by the lighting and actually appear like a lumpy mess.
    Good shading only gets you part of the way there, however. A poorly scaled model can break immersion instantly, especially when you are trying to create a believable real-world environment. There are tried-and-true metrics for Counter Strike so having a base to work from helped immensely, but these only give you a good starting point or a bounding box for your object. It's important to study real world reference and make sure your object is proportional to the world around it and also to itself. A unit in Hammer is an inch, so having wood that's 2 units thick, or a doorway that is 1.5m wide quickly makes things look wrong.

    Working with Designer Blockouts, and not Destroying Gameplay
    Agency was a collaboration, with Patrick doing the design work and me doing the visuals, this meant there was a lot of potential for overlap and working on the same areas, the potential for breaking things was huge.
    Often when you create things as an individual you don't have to worry about version control or stepping on someone else's toes, however when you work with other people either for pleasure or business you, as an artist, need to change your mindset. You are not creating a portfolio piece but rather something functional that has to withstand hundreds of hours of real people playing it.
    Your first role is to support the designer, and this benefits you as well. By creating the basic structures of the level: doorways, window frames, stairs, railings, cover objects etc, you are allowing them to work with the final assets and tweak gameplay according to those assets. Nothing needs to be finalized instantly, it's better to provide a rough mockup of the intended asset so the designer can play around with it and give feedback on the shape, size and silhouette. Once you are both confident it's going to work they can populate the level with these assets which saves you time in the long run, and once you finalize the model and textures they are going to be updated across the entire level without having to manually replace assets.
    It can be difficult to determine exactly when you should start an art pass, especially when a level is constantly evolving. Rather than sitting idly by whilst Patrick was ironing out the design of the level I started on the creation of a few visual test levels to explore materials, lighting and modular assets. Once the first iterations of Agency were created, with rough shapes for important cover and controlling lines-of-sight. I went in and created an art pass and altered many of these original gameplay ideas, simply experimenting with different shapes and designs for the rooms. We had a constant dialogue and never considered something finalized just because it was finished. Playtests would determine whether an idea was valid or not in a way that speculation can only hope for. The most important lesson learned during this process of constant iteration was that work is very rarely wasted, and it is far more important to stay true to a gameplay ideal than to have an area that looks interesting in a screenshot but utterly fails when players get their hands on it. A box is a box is a box, it is down to you as an artist to imagine how that box can be interpreted within the context of the environment.
     

    Initial art pass ideas for the central area (above) versus the end result (below)
     

    Initial art pass ideas for the reception (above) versus the end result (below)
     

    Initial art pass ideas for a hostage (above) versus the end result (below)

    Lighting
    An important part of any environment is the lighting. Too contrasted and moody and it becomes hard to identify players, too bright and monotone and it becomes boring and a strain on the eyes. For Agency I used a series of instanced lighting setups: a model to visualise the light source, a spot light to direct the light, and a sprite or light cone to add a visual effect around the light. Each light setup was unique to the type of model used for the actual light source, ie: all spotlights were identical, all fluorescent lights were identical etc. This meant I could change a single light and have the others update automatically, and always get an accurate result.
    Then it was just a case of placing these different types of lights where they logically made sense in the environment, and if an area was too dark an appropriate light source was added, and if an area was too bright lights could be moved around or removed entirely. This made it quite easy to light as everything was guided by reality, which has plenty of reference material, and had the side effect of helping to make the environment more believable. By using various colours on the floor and walls I could direct lights towards them and take advantage of the Source engine's excellent radiosity and spread interesting colours to nearby surfaces.
    In many areas the ceiling was opened up to reveal the sky and to let natural sunlight into the interior spaces, this was done to provide contrast to the electrical lights and to get extra radiosity bounces into the environment. Some areas had lights removed or toned down to allow other more important gameplay areas to stand out, for example the image below shows how the corridor here was darkened both by using darker textures and by using restrained lighting to make the room in the distance appear brighter as this is an area that enemy players will appear from.
     


    This could have been taken even further by possibly using emergency exit signs to add hints of colour to important gameplay areas and chokepoints. A consistent lighting language would have helped guide players during the first few times playing the level. There are some large open spaces that would have benefited from some coloured screens or lighting panels, or possibly making some of the larger glass surfaces tinted, to add a little extra colour and prevent such a monotone look whilst not being over-bearing or detracting from the realistic style of lighting I was aiming for.

    Final thoughts
    During the course of developing Agency I had a chance to learn a few things and come out the other end a, hopefully, better artist.
    So, what went well?
    The iteration process never had any hiccups, by using modular content and being prepared to discard ideas and art styles that weren't working we ended up with a better level. If we had tried to force the original idea of a ground-level government office we would have ended up with a completely different level, complete with underground parking lots and elevator shafts. Exciting stuff!
    The power of iteration cannot be understated, and understanding that a mockup or a blockout of a level is simply a temporary phase that doesn't represent the end result. Areas changed drastically between versions, sometimes due to design requirements, and sometimes of shifts in art style; but each version was better than the last, more refined and polished.
    What went less well?
    In direct contrast to the statement above, sometimes the iteration interfered with more important tasks. I got stuck on areas trying to get them to work instead of letting them sit for a while and returning to them later. I tried to force an idea for the exterior part of the level and it never felt right and consumed way too much time, when all it took was getting some outside perspective. Luckily during the process I learnt to trust designers when it comes to art, just because they might not build high poly meshes doesn't mean they aren't artistic.
    Another problem was building too much content completely unique for an area which meant when we inevitably changed things it became time consuming to shift assets around, and makes it less easy for others to re-use that content without creating an almost replica of the area it was designed for. These unique assets helped sell the realism of the level but made them harder to work with.
    Hopefully this has been interesting and insightful!
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