Common Infected

See also: Uncommon Infected

"I ain't gonna let these god damn vampires beat me."

- Francis "Holy shit, zombies are real. I KNEW it!"

- Ellis

Common Infected (referred to in The Parish and The Sacrifice comic as Whiskey Delta, meaning Walking Dead, by the Military) are the most frequently faced members of the Infected, and the easiest to defeat. Their strength lies in the fact that they attack in groups, more commonly referred to as the Horde, sometimes as large as several dozen.

While they seem capable of ignoring pain, they are as easy to kill as any normal human is. They are capable of climbing ladders and scaling objects once they find a target, and will not stop until it is dead. The default number of Infected that the Director spawns in a horde is around 30. These Infected are fast, sensitive to loud noises and movement, and able to attack in ravenous waves, as determined by the Director. They might not notice The Survivors right away, but when they do, watch out—they're fast, and it won't take long for them to close the distance.

The Horde
The "horde" is a term people often use as a reference, to a medium or large amount of Common Infected. A horde of zombies can be powerful but they are not invincible by any means. These hordes can often be distracted very easily in many ways. For example, the Survivors mainly attract the Common Infected via loud noises and bright lights.

There are several occasions throughout each campaign, called Crescendo Events, where the Survivors must do a certain action, such as opening an emergency door that will set off an alarm, or turning on a noisy generator, that alerts the horde in order to proceed to the next segment of that chapter. There are also other times where the Survivors may accidentally alert them by setting off a car alarm, or if Re: Your Brains starts to play on a jukebox. All of these trigger something called a Crescendo Event, which causes a large horde to spawn and attack the Survivors. When a pipe bomb is thrown, all of the Common Infected in the immediate area will come to investigate the loud beeps and flashing lights, chasing the pipe bomb and clustering around it until it explodes, killing them. When the Common Infected attack from the front, they do approximately 1 damage on Easy, 2 on Normal, 5 on Advanced and 20 on Expert, and when they hit you in the back, they do half as much damage.

Appearances and Action
Common Infected come in variety of appearances, both male and female, such as patients, nurses, construction workers, military personnel, and airport staff, the differences only being cosmetic. They are the vulnerable victims of the vicious virus only known as The Infection, though referred to as "The Green Flu" by newspapers, TV, and on the Midnight Riders website that is sweeping through the area. There is no true theory as to how the infection is spread. However, there are theories from various in-game stories, and even in grafittis, as well as the official comic, that say it is spread through biting, scratching, clawing, blood, water, air, and other various sources. It seems that the Common Infected in Left 4 Dead 2 almost have the same base model, but with slight changes in hairstyle, clothes, and blood marks, while in the first game, there are many different models that stay the same. This is to save memory in the second game, so the Pipe Bomb would now create ragdolls and the Minigun/50cal being able to make gibs.

<!-- This info below needs to be cleaned up A LOT and moved to a different section of the article, will make it invisible for now

The first Infected are said to being "good", the cop is "local flavor" in some of the game areas while the other ones are like extras. These should be visible but not memorable or as if they were clones and had dedicated textures for the body geometry.

Left 4 Dead's Common Infected had limited sharing of different head textures, mostly on male Infected. Making all the maps not looking good on all geometry variations. Color tinting was used by multiplication, the lighter/darker details must be visible under all tints. Untinted things have medium-value base to allow a bit of contrasting detail, it starts dark and only gets darker. Analysis explains that 2 things that didn't work were texture variation that didn't change any contrast or even any fine detail of any sort. What did was geometry variations that changed proportions or just moved features around and large, different color shapes possibly known as "color blocking". The color blocking has concept from traditional painting, it also has a bit of under-painting of a local color without applying shading nor detail. It is also supposed to figure out the local color: what did you see from a distance? Things that Valve learned were that tinting must change the color blocking, being best if it can or does  affect contrast between local areas of the color and that the geometric variation must also affect the color blocking. Another important thing is that the color blocking also works at close range, the blood patterns helped getting mileage out of variants of playtesters mistakenly perceived as clones. The prototyping of the variation system, a prototype in external application, should be no overhead of the implementation in-engine until they're sure. Also choosing the application that allows for distribution to end users which was the HLSL plugin for Maya.

Much later they start with the biggest effect for the least investment called tinting and gradient mapping. The gradient mapping works just like in Adobe Photoshop, but it should luminance the values only and map every pixel with the same luminance to color the specified in a gradient ramp. However overdoing the colors doesn't and will not work. This fits well with some DXT compression scheme, it only needs a single channel, the alpha has the most fidelity and the alpha compresses the independently from RGB (Red Green Blue). It can't overdo the colors, but it can't tint the character with the same gradient ramp either. When doing this the artist or person must avoid Monochrome results, the RGB can be used for masks and the skin and clothing must be masked seperately. Another feature that was used was "masking the blood and grime", in Left 4 Dead the players identified different textures as clones and the Common Infected used blood to differentiate the similiar textures while in Left 4 Dead 2 the players should identify the same texture as different, also the Common Infected had blood masking applied to then in order to disguise the identical textures.

When masking, the Blood and the Dirt masking can be used to add blood and store all variants in the existing texture, splitting the texture into quadrants and store 4 masks in the dedicated channel. It also uses 2 texture lookups which were a 1/4 size to select a single mask and a full-size to get the luminance from the alpha, should be done the same for grime. The blood is a solid color while the grime doesn't have to be this, can use a detail texture that can vary depending on the environment. Can be anything like mud, algae or so. Might result in being able to make green, purple, blue, azure or even orange. Some discussion and additional feature requests are:

Initial results promising: some good overall range of luminosity, individuals still relatively being monochrome, the blood-splats being a bit blurry since the masks are 1/4 sized, unfinished goals for the first Left 4 Dead were retro-reflective effects of eye-glowing in headlights signalling the inhuman nature of infected. Specular masking was used because of the lack of normal maps. Their texture budget is limited, so using normal maps would mean halving their texture budget which would mean half the variation and they have got to look at the fidelity of the horde as a whole and not its individual members. Things that were used were 6 masks in 3 channels, listed below:

Skin tinting

Cloth tinting

Blood

Grime

Retro-reflectivity

Specularity

With so many masks they choose to give up the normal maps for variation, the answer to this is "No way are we adding another texture just for masks!"

Exlusive masking says that the Cloth and Skin don't overlap and shouldn't, it can also use different value ranges to mask each effect. Modify the mask in a shader using a levels-like operation, moving the blackpoint to ignore all values below value 127, resulting in a proper skin-tint mask. Should be done the same for cloth-tint masks, but must be inverted first (G-Major effect), all values above 127 should be ignored, resulting in a proper cloth-tint mask. The result is that you can mask two seperate gradient mappings by only using a single channel, this only works because the masked areas do not overlap.

Storing the information: Use the exclusive masking and pair up effects with Spec...Detail (Specular Detail), Blood + Retro-reflectivity, Clothing tint + Skin Tint and last but not least luminosity in the alpha. Should use a specular mask from the detail's alpha in detail-masked zones, this can pair the blood and retro-reflectivity, at least if the blood gets some priority. The blood on top of a retro-reflective material damps the retro-reflectivity anyway. A smoothstep for blood patterns, lose some of the painted detail, get back the hard edges.

One last problem is: The individual infected still look relatively monochrome, modify the ranges in luminosity for further color variation, create a more complex gradient ramp, limit the luminosity in areas to map to only a portion of the ramp. Next step is modifying the ranges, screenshots needed here. In the end of modifying the ranges it will need buffer between the ranges because of compression. On geometric variation, much of the texture is shared, it helps render batching, and texel density in areas players focus on are:

Torso which is the center of gravity, direction of motion and intent to move

Head for when the AI has spotted a target

Hands for attacking

Authoring the textures a bit later says that all geometry variations are made first and unwrapped together. There are lots of steps, making a high probability of an user error which is an obvious candidate for scripting.

Let the texture artists see the final result while working, the shader does a lot of compositing with the masks. Photoshop is also pretty good at compositing, after this a review of what the shader does comes. Screenshot needed, after that step a standard configuration with named layer sets should be created. A script setup and reconstruction: It uses gradient adjustment layers, pattern layers, and some solid layers for masked effects. The blood and detail painted at full size, one at a time and is hidden when it is not needed. The luminosity is painted at a full range, levels adjustment layers push the values into correct ranges for gradient mapping. A specular mask is painted in the same file, is hidden when not needed.

Results in Photoshop looking remarkably congruent with the in-game result, 4 screenshots needed.

The Zombie Recipe: Each Common Infected cotains 2-3 head textures with 4 blood patterns each, 4-7 head geometry variations, 1 body texture with 4 blood patterns (just like the head textures since they also have 4 blood patterns each), 3-8 body geometry variations, a detail from a shared texture and 8 skin & clothing tints from a shared 16x256 texture. The "Uncommon" Common Infected like the construction guy have their own dedicated palette. Insert screenshot of gradient palette on Zombie Recipe Page 1 here.

The simplest Infected have over 24,000 variations, the levels use as many as 6 models, as few as 2 models. This depends on memory, maybe costuming too. Creation time is a bit less: it made fewer, more effective textures. Picture of final results needed here, the measuring success makes 50% less memory usage, 10 times more variation, the lighting is done per vert instead of per pixel. Vertex shader instructions will be increased by ~100 and the pixel shader is comparable with Left 4 Dead. And finally, only "Uncommon Commons" stand out.

End of information on The Horde with changes from L4D1 to L4D2, explained a bit of gradient mapping too. --> Common Infected do not differ in appearance from a sick human as much as Special Infected do. According to the game commentary, the developers designed multiple types of faces and bodies, and would have the computer pair them when spawning Infected, ensuring a variety of characters. This allows for "something around 1500 possibilities". Some Infected models can be seen in any scenario of the game, while others, such as the Infected patients in Mercy Hospital or airport custom officers in Dead Air, are only encountered at certain areas.

When not attacking, they are very vulnerable, usually sitting down, leaning on walls, or simply standing. Usually, when in this state, a Common Infected can easily be taken down instantly by a shove or melee attack; they must be unaware of the Survivors' presence to be taken down with one hit. They are easily provoked by light, sound, or touch, but are normally only dangerous in large groups or when completely surrounding a player. The heads, arms and legs can all be shot or cut off, this happening easiest with the use of a powerful gun or a slicing melee weapon. The Infected react naturally to gunfire in their vicinity, turning towards the sound to attack the shooter. Shooting one in the foot will cause a very different reaction than shooting one in the chest with a Pump Shotgun. Usually, if an idle Common Infected receives a non-fatal gunshot wound from a distance they will writhe in pain and clutch the wound with their hands, but if they are running towards the player and receive a non-fatal gunshot wound they will just continue to pursue the player and ignore the pain. This can be most easily observed by shooting them with a Pistol.

They are often seen engaging in bizarre activities (e.g. vomiting, attacking inanimate objects, fighting each other, showing that the sickness may still be affecting them even in this state, even perhaps killing them rather than keeping them as Infected) when unaware of the Survivors, but begin to rush at the Survivors the very moment they see them. Very rarely, an Infected can be seen facing a wall and making mumbling noises, as if talking to itself. A Common Infected's attack slows down the target player, making it exceedingly difficult to run away from a mob of them that is close to you. They also seem to be at least smart enough to attempt to trap the player, commonly running ahead of him or her and attacking from in front to prevent movement, assuming there is also a horde or something like a Tank behind the player.

The Infected appear to lack a sense of self preservation, as they will actively charge into flames, explosions, jump off from high buildings, and against superior forces of the Survivors and their weapons, even if they have encountered these things before. This can be best observed by throwing a Bile bomb into a fire in The Hotel. A possibility is that the Infection has affected their brains to such a degree that they only think of spreading it, or may simply think of attacking anything that disturbs them from their vicinity. This could mean that the Infected ignore their injury, only to attack the Survivors. When approached by a melee-wielding survivor, the Infected frequently dodge or duck from the attacks. The Infected also rigorously make flanking attempts, trying to hit Survivors from the sides or backs as to avoid danger. The Infected also are not known to feed or drink, however, they can still survive, as in the first level of Dead Air, there is a piece of graffiti that says "They don't eat, they don't sleep, what keeps them going?", and it is possible that the Infection has removed the mental ability to perform these necessary life functions. This may indicate that the Infected may eventually die of starvation or dehydration, and possibly even exposure to the elements as the Infected do not seem to seek shelter in conditions that non-Infected would (the theme of the Infected dying out and repopulation commencing is similar to what happened following the events of the film 28 Days Later). However, it's possible that the Infected resort to cannibalism, as evident from the blood on their mouths. It is also possible that the Infected just bleed from their mouths, but it is more likely it is just blood from earlier victims.

Common Infected hair and skin pigmentation is usually very low, resulting in a pale gray skin, which explains the gray skin and white hair color of the Witches, lesser Infected may also have pale hair, though some female Common Infected have dark, blond, or red hair. Some Infected, such as Boomers and Smokers, may have black or dark hair. The Infected appear to be capable of many acrobatic actions, such as climbing fences, climbing walls and many other actions to get at Survivors.

Location Common Infected
In both Left 4 Dead and Left 4 Dead 2, there are special Common Infected that are only found on specific areas or chapters in different campaigns. Unlike the Uncommon Common Infected, these Infected individuals only look different in appearance and do not have any special abilities.

No Mercy
In the final two chapters of this campaign, the Survivors come across Infected doctors and nurses as well as patients at Mercy Hospital. The hospital staff were trying to treat the infected individuals however, they too became infected themselves.

Dead Air
In the final two chapters of this campaign, the Survivors pass through Metro International Airport finding several infected airport staff such as TSA agents, baggage handlers, and airplane pilots as a result of when the infection hit.

Dark Carnival
At Whispering Oaks Amusement Park there are still members of the park staff seen by the Survivors. When CEDA converted the park into an evacuation center, they were assisting in the evacuation by directing civilians and trying to maintain a level of calmness with the public however, due to the severity of the Green Flu virus, they too became Infected.

Hard Rain
There are hillbilly Infected in the town of Ducatel which are commonly mistaken for Chargers due to the fact that they look like Chargers since both of them wear the same type of overalls.

Extent of Mutations
Though the Common Infected have evidently been mutated the least physically by this strain of the infection, the strain appears to have had a bigger effect on their minds. They seem to have lost many of their higher brain functions. However, their sense of smell and hearing have been greatly enhanced, possibly explaining things such as Crescendo Events and how the Infected are able to notice the Survivors from the littlest things, such as the Boomer bile. It's possible they've had very slight boosts in strength (as hinted by their capability to break walls and take a Survivor down in a few hits on expert difficulty), speed, and endurance—though, again, it appears to be slight, as they don't withstand many bullets or hits in general. Perhaps due to loss of higher brain functions, they seem to ignore pain and damage even when their limbs are blown off.

An exception to this, is the Fallen Survivor from The Passing, which will run from the Survivors once shot, as opposed to other Common Infected. There seems to be little explanation for this behavior, other than the individual's will to survive surpassed the Infection or that they have a strain of it that affected their sense of self preservation less, though, despite this, they still seem not to notice wounds that would be fatal if left untreated, such as a severed limb. The Infected also tend to be incredibly hostile to anything not perceived as being Infected, though there are occasions when two Infected are seen fighting one another and even killing each other. Additionally, the bodies and bones of the Infected seem to have weakened, seeing how their bodies explode with blood when they are shot/chopped, compared with how a normal human being would react. Overall, they seem quite animalistic in nature.

If nothing else, they seem to have some grasp of their current situation, or at least how they feel; generally, idle Infected act physically ill, holding their heads and vomiting as they shuffle around slowly. Occasionally, if you watch one long enough, one of the Infected who is holding their head may begin to writhe in pain, or they may simply lie down and sometimes die without being shot or punched, suggesting that the virus is deadlier than it seems. It is also possible that after Infection, they have a limited life span, just like how people Infected with rabies (the virus the game's virus was based on) have a limited lifespan if left untreated. It could also be through brain hemorrhaging, as Infected appear to bleed out the ears and eyes. This also explains why they hold their heads in pain. Another possibility is that these deaths may be the result of an injury that the Infected person received earlier, such as from a gunshot from other Survivors or from a fall that they endured. They are shown to have a primitive but working communication system with others, generally through grunts and screams. In the comic they are also shown to see the Survivors as something inhuman, or something of the sort, which may explain why they attack them. It may even be that symptoms of the Infection include immense hallucinations followed by adverse paranoia which leads them to attack nearly anything they see moving, including their own kind on various occasions.

Tactics and Tips
Common Infected are only strong in numbers. Sticking together is key to keeping them off you and your teammates' backs. If you are concerned about conserving ammunition, consider using the pistol, which kills them in just a few shots or in one head shot on any difficulty, not to mention it has infinite ammo. It is possible to kill a Common Infected simply by jumping on their heads. To do so, simply walk off an edge which is at least a little taller than the Common Infected, and onto their head. Hitting a Common Infected from behind can instantly kill them, and earn the player the SPINAL TAP achievement.

Closet mode
When a horde is about to attack, the best tactic is to back into a corner (preferably) or a wall. Assign the front two Survivors to crouch and melee continuously (not viable in Versus or Survival mode in Left 4 Dead) while the two Survivors behind them stand and fire their weapons at them. This works equally well when Survivors have been covered in Boomer bile. Finding the nearest door, closing it, and using a shotgun to blow out a significant chunk of it provides you with a shield that you can see through, as well as keeping the Infected from touching you—very useful for higher difficulties. The most important thing is limiting the area the Common Infected have to attack from. You may also throw a pipe bomb to divert the Infected once you have been covered in Boomer bile

Note: This is not recommended for Left 4 Dead 2. This is because the Director will eventually spawn a Spitter or Charger that will force you away from your position. Ultimately, this will bring you out into the open, possibly surrounding the player with even more Infected. Also, a patch for Left for Dead ' s Versus and Survival modes (consequently passed on to Left 4 Dead 2 in all modes) implemented Melee Fatigue, which will force a short pause after five rapidly consecutive melee hits, and then after every hit until a 'cooldown' has been taken. The cooldown usually lasts anywhere from one to three seconds. However, Melee Fatigue can be negated for a short period of time by the use of adrenaline.

Remove Loners
Pick off lone Infected that have strayed away from fellow Infected whenever you can. When entering a new area, swap to pistols or snipe via a hunting rifle or a sniper rifle and take out as many lone Infected as you can from the entryway as long as it stays quiet. The Director has a tendency to spawn hordes once you reach the mid-point of areas, and this "event" will cause any idle Infected in the area to attack as well. In Versus, however, it is unlikely the Special Infected will allow you to sit in one place long enough to clear a room in this manner, so keep moving.

In a safe room it is often a good idea to stay by the door and pick off any Infected that you can see. They can't hurt you if you're inside. This can make for an easier exit from the safe room.

Weapon of choice
All weapons possess the ability to fire through multiple Infected, therefore positioning yourself so that the Infected are funneled into lines is effective.

Any shotgun can be very useful against the horde, as their shells deal large amounts of damage and can pass through multiple Infected. The Auto Shotgun and Combat Shotgun are slightly superior as shotguns go, as they can decimate groups in mere seconds, and there is no pause to pump the gun. A good tactic to use if they are coming through one area, such as a doorway, is to keep your fire pointed at the entry, as the Infected will be clustering together to get through, making them easier to kill. Remember to push the Infected back while reloading simultaneously taking into fact that the shotgun will take much longer to reload than any automatic weapons. It is also a good idea to aim low when using a shotgun against smaller hordes, since gibbing the legs is an instant kill towards Common Infected.

As far as automatic weapons go, the rifles can do major damage at any range. The Combat Rifle excels at accurate long-range shooting, but when a horde is in a player's personal space, it will lack the automatic fire and power to dispatch the Infected quickly. The AK-47 is the opposite; while it is poor at best at taking out distant enemies, its high power and low accuracy spread can clear out Infected in mid-to-close range. As for the Assault Rifle, its a medium grade in between both the Combat Rifle and the AK-47, it has a decent power and long range, fully automatic and good accuracy.

Given the Hunting Rifle or the Sniper Rifle, both should only be used to kill distant Infected. If need be, they can be used to kill attacking Infected with their high rate of fire. However, the rifles do excel at one thing: bullet penetration. If multiple Infected are being funneled through a tight area or are otherwise "stacked" (like when climbing an obstacle), the rifle family can shoot through several Infected with a single bullet.

Power of the Horde
The Common Infected are especially dangerous on the expert difficulty. It can only take a couple of hits to down a Survivor, depending on the Survivor's current health. On this mode, the Common Infected also deal much more damage: 20 for each hit on the front, and 10 for each hit on the back. This means a Horde can easily cripple an entire team if they do not pay attention. The Infected often run up behind Survivors and hit them in the back, downing them before they can realize that they are being attacked. To avoid this, constantly watch behind you and look for Infected sneaking up behind your teammates, but do not shoot when they are close to Survivors to avoid friendly-fire. Instead, Melee them off, and then shoot. A good tactic is to always have someone watching behind the group. Communication is also key; always tell other Survivors when they are in danger. Also, it might be a good idea to hop on top of a car or van that has no alarm set because higher ground is usually recommended for fighting large amounts of Infected. Horde attacks also slow down players, if they do not communicate this to other players, they can easily be left behind.

Darkness is your Friend
The Common Infected are obviously known to be attracted by the noise of car alarms and other loud sounds caused by most Crescendo Events, however, most have not realized the flashlight can also enrage Infected. Its effect is similar to that of a pipe bomb, as the bright, flashy lights irritate them, drawing their attention to the player. Flickering the lights on and off will disturb them faster. Using this knowledge may help if two of the Survivors have their flashlights on while the others do not, causing the two "aggro men" to become focused on while their partners are able to break off the rest of the Infected.

In addition, the glare of the flashlight can sometimes cause your vision to focus directly at where the flashlight is pointed at. Shutting off the flashlight during a horde is usually a good idea, and practice using the silhouettes to identify Infected. In low-light situations this can drastically improve your vision of oncoming Infected. In addition, most Left 4 Dead 2 levels are in areas with generous light, yet shining your flashlight on the Infected will still disturb them. Use natural light whenever possible to avoid Infected.

Duly note that having a flashlight on whether it's day or night time and whether or not you shine it directly onto an Infected doesn't matter, it seems to aggravate them from anywhere nearby if the Flashlight is in sight. This kind of behaviour exemplifies the Common Infected's animalistic traits.

Playing smart
Although Common Infected are easily dispatched, it is still very important to eliminate them when possible and still pay attention to one's surroundings. In the event of a Horde or Crescendo Event, communication between players is necessary in order to avoid Special Infected ambushes and separation. Having a predetermined path and assigned combat roles can all contribute to a successful campaign or versus match. Also sometimes, when Infected are near a wall, their shadows can be seen through the walls, giving you a chance to plan or dispatch them before they become troublesome in a horde.

Targeting priority
The Common Infected's targeting priority is:

Thrown Pipe Bombs > Survivors or Infected who are covered in Boomer bile > Thrown Bile Bombs > Survivors (Only during hordes, Panic events, Crescendo events, Finales, or after they realize Survivors' existence).

Notice that sometimes Common Infected will not switch their target when they are already attacking a Survivor. Survivors have to shove them to make them switch targets.

Infected tips
When playing as the Infected in versus, you can use the Common Infected to your advantage. While the Survivors are attempting to reach the safe room, there are many ways you can exploit the Horde. Once the Survivors are occupied by the Horde, a competent Tank can defeat even the most organized Survivor team. Boomers can not only summon the Horde but also "extend" it by vomiting on the Survivors after they have dealt with the present Horde. Vomiting on downed Survivors is extremely effective and will very often result in death for the Survivor unless someone goes to help them deal with the Horde. Smokers are also effective during a Horde as they can snatch a Survivor and pull them away whilst the others are too busy fighting to help. Smokers can also be protected by the Common Infected. If you have snared a Survivor and you pull him in front of you where you can hit him, the Horde will attack along with you, killing them faster. This circle of Infected makes it harder for the Survivors to kill you. You can even do a substantial amount of damage with a Hunter before the Survivors can deal with the Horde and kill him. Other Infected will also surround the Hunter to claw at the Survivor. There are around 30 Common Infected within a Horde. During a Horde attack is the best time to work together, Special Infected need to cooperate and doing so with the Common Infected can be fatal to the Survivors.

Achievements

 * See Main Article: Achievements

Left 4 Dead

Left 4 Dead 2