unique_copy (output.begin(), output.end(), std::back_insert_iteratorstd::string(_justDialogue),
[](char a,char b)
srt
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I'm going to use a few terms throughout this video that not everyone might understand.
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A plane is a mathematical term for a square or rectangle.
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This is mostly the walls, ceiling and floor.
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Vertices are the corners of said planes, the singular being vertex.
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Polygons are another term for surfaces derived from computer science rather than maths.
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It's going to be used interchangeably with plane.
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To do something recursively means a process must repeat itself over and over until an
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end goal is met to solve a problem.
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A data type is a way data is classified in programming.
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For example, a string, which are words or a series of letters, and int, which is an
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integer, a typical number.
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There are different kinds of numbers as well, such as float for precise decimal numbers,
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and long for, well, long numbers.
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Of the total size of the games industry today, around 20% are games within the shooter genre.
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Around a fifth of games in this $300 billion industry are shooters, most of them being
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first person shooters.
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The amount of money generated by and riding on the success of this singular genre in this
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industry is stupefying.
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The first person shooter as developed early on was a huge departure from every other kind
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of game that existed at the time.
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Games at the time, PC games especially, were often slow or methodical.
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The personal computer platform was known for careful and considered games, turn-based strategy,
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grand RPGs with a slowly unfolding world.
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Often times these games would be indistinguishable from a spreadsheet.
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Action was the realm of console gaming.
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Platformers were the most immediate real-time action-packed games available, and besides
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notable games like Duke Nukem and Commander Keen, people didn't really play those kind
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of action games on PC.
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This was until the advent of the first person shooter.
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Suddenly people were hit with this visceral representation of violence.
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They represented something which films could not.
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You inhabit a world through the lens of the character.
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You are closer to the action hero than ever before in any medium in history.
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What is widely agreed upon as the first first person shooter ever is Maze War, developed
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in 1973, that's the same year Britain joined the European Union, Dark Side of the Moon
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was released, and the United States announced it would withdraw from Vietnam.
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It was developed for NASA computers by Steve Colleade, Greg Thompson and Howard Palmer.
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It was constructed with simple wireframe graphics.
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People had the idea of adding multiple players using networking, then connecting over the
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ARPANET.
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Then it took off.
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We saw other first person shooter games after that point.
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Spasm or Space Sim in 1974, Battlezone for arcades in 1980.
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Besides these few examples, for the majority of the decades following its inception, the
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first person perspective was known mostly for its association with the role playing
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genre, for example games like Ultima.
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Now, first person shooting did technically exist, but you were merely shooting projectiles
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at your friends.
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You weren't inhabiting a character, you weren't the action hero fighting bad guys,
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That was until Wolfenstein 3D.
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id Software was founded in 1991 by four former soft disk employees, John and Adrian Carmack,
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no relation they just happened to have the same name, Tom Hall and John Romero.
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This was the same year the Soviet Union fell.
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Carmack is going to be more important later on.
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They originally began with a Mario clone named Dangerous Dave before the company was officially
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founded.
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This was mainly to show off the beginnings of John Carmack's technical wizardry, encoding
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an efficient 2D side scrolling graphics renderer.
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The early 90s, when everything was a dark and edgy statement, the satanic inversion
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between PC and console was no exception.
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PC graphics using software rendering were terrible.
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John Carmack developed his adaptive tile refresh for the PC to compete with the raw computational
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power of the Super Nintendo, a true beast.
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Adaptive tile refresh meant that slightly more of the game world could be included in
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the screen buffer, just outside of view.
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This meant they could render smooth 2D scrolling.
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It also made the sprite animations independent from screen scrolling.
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This little bit of code magic powered their games, including the Commander Keen series.
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The Commander Keen series was spread through shareware, with subsequent episodes releasing
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over the next year or so for purchase from Apogee, their publisher.
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This shareware model would be important because it would be used in their subsequent games.
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Speaking of subsequent games…
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Wolfenstein 3D began development in 1991.
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It would use the raycasting technique earlier employed in id's Catacomb 3D.
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Raycasting was a rendering technique necessitated again by the limited processing power of PCs
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at the time.
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PC master race just can't stop losing.
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PCs almost all used software rendering, rather than a dedicated graphics chip.
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The shareware model involved getting the game on as many PCs as possible.
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Raycasting was the solution to help them do this.
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Raycasting allowed their game to run on basically any PC.
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Raycasting means you're able to draw only the surfaces which are in the player's field
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of view.
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This helped massively in saving processing power.
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But how does it work?
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In effect, a ray is cast, from the player to the geometry, to the nearest object blocking
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its path.
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In Wolfenstein, none of the levels were truly 3D.
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Every level was drawn out on a flat 2D plane.
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The program scans horizontally, checking that every pixel on the horizontal axis has something
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drawn in it.
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If there's nothing drawn in a position, a pixel column will be drawn out.
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This is simplified from the process of ray tracing, where this process is done for every
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single pixel, rather than every pixel column.
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The distance between the viewer, or the camera or player, they all have the same meaning,
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and the nearest piece of geometry, is obtained.
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The height of the pixel column is calculated using the distance from point of intersection
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in the direction the player is facing.
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It uses trigonometry to find this point of intersection.
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This effectively allowed them to give the illusion of distance, to render a 3D scene.
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This makes the process of rendering 3D much easier, as a line, that line being distance
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from player to geometry, directly transforms to a line, that being the height of the rendered
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column.
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This process is done multiple times every single second.
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The planes in the scene had been texture mapped, where an image is applied to a 3D surface.
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When the columns are drawn, they are really drawing slices of these wall textures at different
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sizes.
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The height of the column being drawn is smaller when the plane, that being the wall, is further
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away from you.
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The textures are scaled appropriately to the size of the wall, relative to the player.
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This gave the world of Wolfenstein so much believability for the time.
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You were no longer just navigating wireframe mazes.
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You were an action hero, BJ Blazkowicz, infiltrating a Nazi castle.
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The walls were adorned with flags of the German Reich.
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You felt closer to the world than ever before.
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You were interacting with a true 3D space.
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This process was, however, flawed.
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In Wolfenstein 3D, there was no verticality at all, no difference in elevation, only the
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walls had texture, the ceiling and floor had to be flat colours.
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If they wanted texture on the ceiling and floor, they would have had to add horizontal
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scanlines.
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You were still ultimately navigating a maze.
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A colourful maze with Nazis in it, but a maze nonetheless.
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Wolfenstein 3D was released in May 1992.
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The sequel, Spear of Destiny, was released later in the same year.
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While the rest of the id team was working on Spear of Destiny, John Carmack, the ascetic,
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high priest of technology, locked himself away to study.
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He would brainstorm the revolutionary tech that would power their next massive game,
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the next game that the rest of the team would start working on in September 1992.
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It would be something inspired by evil dead, brutal and violent.
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The name, Green and Pissed, was ultimately passed up for the much snappier Doom.
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Doom would launch in 1993, the game would truly be able to transport you into a world.
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The levels truly felt like places.
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The architecture of Doom consisted of supernatural science facilities, with Giger-esque and hellish
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environments as well.
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The enemies were a combination of horror and sci-fi with cybernetically enhanced demons.
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The architecture, over the top setting and violence was inspired by films such as Evil
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Dead and Alien.
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The floors could now be angled, they could now have multiple levels with stairs and elevators.
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Tools of toxic fluid surrounded these risen platforms.
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It was truly 3D.
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But it wasn't really.
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They were yet to achieve the full 6 degrees of freedom that John Romero wanted.
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This wouldn't happen until Quake.
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Rumours couldn't be stacked on top of each other, there was no vertical aim, the game
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was entirely played on the horizontal axis.
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The thing is, vertical aim was actually possible at the time.
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They could have limited the enemies' vertical hitboxes to the size of the sprite, but they
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didn't.
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Not because they couldn't, but to save processing power.
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You see, Doom was still using software rendering.
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This shareware model relied on getting their games on as many computers as possible, like
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I said.
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It was essentially the beginning of the free to play game model we have today.
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They aimed for the IBM PC, for machines running DOS.
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They had to sell their game to university students and wagies who were bored at work
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so they could run office tournaments.
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They didn't calculate the enemies' vertical hitbox so that they could save memory.
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They didn't want to give the enemies' hitboxes a height value, just have another factor to
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calculate.
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These levels were drawn on a 2D plane, like Wolfenstein.
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Just this time, the map creator is quite different.
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The ground is divided into sectors, this will be very important later.
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Each sector has two associated values, ceiling height and floor height.
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Well, it has several associated values, but those are two important ones.
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This is also why one room could not be placed above another and why every surface had to
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be made out of a flat square or rectangle.
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Another reason that vertical aim couldn't have worked is due to how the texture mapping
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worked.
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One game that did have vertical aim and levels on top of each other, before Quake and not
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that long after Doom, was Bungie's Marathon.
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And look what happens when you look up and down in that game.
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The textures start to distort.
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This is because the game, like Doom, uses affine texture mapping.
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This, like many of the other methods, was done to save memory on the processor by taking
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advantage of CPU caching.
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Basically, what happens is that texture coordinates are linearly interpolated, using screen space
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distance between vertices, rather than the actual 3D in-engine distance between them.
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The distance between points on a plane remains the same when you look up and down.
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What this means is that perspective when looking up and down is not accounted for.
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You know how pixels on a texture start to warp as you get closer?
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It looks like a straight line from far away begins to turn inward as closer pixels get
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larger, while more distant pixels get smaller.
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This doesn't happen in Doom, because accounting for perspective is taxing on 90s computers.
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You know how the game only draws things in columns to save processing time?
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They'd have had to do vertical scans as well as horizontal scans.
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Newer ports of Doom with newer rendering engines made for new hardware like GZDoom obviously
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don't have this limitation.
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As such, they use more current texture mapping and don't have this issue.
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But all of these concessions weren't enough.
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John Carmack's coding brilliance met its most devious enemy yet.
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Stairs.
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John Romero came out with a really way-out and strange idea on his early incarnation
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of E1M2.
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Yes, he wanted to mix things up with the earth-shattering invention of stairs.
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You see, just raycasting alone wasn't enough to efficiently optimise the game.
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Raycasting saves memory by only rendering things which are visible to the player.
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However, surfaces on the inside of these stairs were visible to the existing algorithm.
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Thus, they were drawn when they shouldn't have been.
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You see, for 3D rendering to not waste performance, they need to draw as few surfaces, as few
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planes as possible.
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This necessitates occlusion culling, or visible surface determination, or backface culling.
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Basically, the renderer should only draw what is in the player's field of view.
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There need to be absolutely no overdraw whatsoever.
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Adding height as a variable, such as with Romero's stairs, requires a much more sophisticated
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algorithm than was present in Wolfenstein, and in id's existing rendering engine.
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There are many different rendering algorithms out there, it seems that we need to dip into
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the hypothetical algorithms to start trawling the literature for some better algorithms.
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Let's explore some of the options.
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There's the painter's algorithm, named so because, like in a painting, the background
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is rendered first with detail layered on top.
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Basically, the polygons are sorted by their distance from the viewer, and the more distant
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polygons are rendered first, and the closest polygon is rendered last.
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It is easily the most simple solution.
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It was developed in 1972, the year MASH started, as an easy to implement solution for CAD.
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It also has the worst possible case for space complexity, meaning it takes up as much memory
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as an algorithm possibly could.
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Every single surface in the field of view is drawn.
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Obviously, this isn't a good fit.
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It's more of an example from the early days of exactly what not to do.
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There's also Warnock's algorithm.
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John Warnock was the founder of Adobe, and this algorithm originated in his doctoral
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thesis in 1969, the year man landed on the moon and In the Court of the Crimson King
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was released.
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Essentially, it recursively subdivides the screen into four parts.
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What this means is it splits the screen into four windows and splits each window into four
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smaller windows.
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It does this again and again until each window is trivial to render, meaning it has only
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one or zero polygons present.
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The algorithm also checks if multiple polygons are within one window.
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If the closest polygon covers the whole window, then it is drawn.
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This is more efficient than Painter's algorithm as it renders front to back, but it's still
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not very well suited.
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It will eventually keep subdividing to a ridiculous degree, to the point where a window is smaller
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than a pixel.
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Yeah, this ain't a good fit for a game.
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You could do a z-buffer for every pixel you want to draw, check if there's anything in
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front of it.
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And check on every single pixel?
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Yeah, there's no chance in hell.
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The final solution does kinda use a z-buffer, but it doesn't do that check on every single
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pixel, it finds a much more efficient way to do it.
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No.
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In order to truly revolutionize not just gaming, but 3D graphics forever, our protagonist,
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John Carmack, needs to go to a much more inspired source, something that hadn't actually been
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implemented before.
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Something he'd just read in a white paper.
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Just a concept.
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Yes, how common is it in gaming to see people run into optimization issues and seek out
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a white paper to solve their problem, because nobody else had done it before?
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Yes, that's Carmack for you.
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We needed a renderer that would draw objects closest to the player to furthest away until
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every pixel was written to, that had no overdraw.
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The solution was in a 1980 white paper, as the same year Genesis released the reclaimed
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album, Duke, where they really came into their own.
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00:15:37,960 --> 00:15:45,820
This 1980 white paper by Bruce Nailup was given the humble title, On Visible Surface
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Generation by Apriori Tree Structures.
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It described a rendering model we know as Binary Space Partitioning, or BSP for short.
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This was the method that would change gaming for years.
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This wasn't the first time Binary Space Partitioning was alluded to.
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A 1969 study by the Air Force of the good ol' US of A alluded to the use of partitioning
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3D scenes to solve the visible surface problem.
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The study was conducted to determine the viability of 3D for flight simulation.
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We can thank the armed forces of the United States for giving us doom.
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They explored using a matrix to track which objects are occluded.
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These of course wouldn't do so well as the size of the matrix would need to be the square
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of the number of objects in a scene.
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That wouldn't scale very well.
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It wasn't until 1980 that Binary Space Partitioning was properly realized in the white paper that
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would reach John Carmack alongside its core tenant, the binary tree.
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But what is Binary Space Partitioning anyway?
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Well, the name gives you a clue.
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Is partitioning space in a 3D environment?
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This is done using a BSP tree.
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What is a BSP tree you may ask?
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In computer science, a tree is a data structure used as a mathematical model for displaying
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certain data types.
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It's separated into nodes with parent nodes that have child nodes.
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BSP uses binary trees, binary essentially meaning two.
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A binary tree is a tree where there are two or less child nodes stemming from any given
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parent, from any node.
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There are never more than two child nodes.
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This is as opposed to a non-binary tree, which is a tree that has dyed hair and a gender
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studies degree.
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The data stored in the nodes of the binary tree are the sub-sectors of the map.
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Sub-sectors being smaller parts of those map sectors I spoke about earlier.
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Remember, each map is designed on a flat 2D map editor, with each sector having associated
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height values.
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The genius is that the map is sliced up via binary space partitioning after the map is
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built.
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Hard work is done when the map is created, rather than by the processor at runtime while
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the player is playing the game.
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The map is already split, already partitioned when the player loads it, reducing processing
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needed at runtime.
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To create the binary tree, a root node is established covering the whole map.
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After this, the map is recursively subdivided along every plane until only convex sub-sectors
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are left.
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The sectors are carved into smaller sub-sectors.
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The entire map is essentially cut in two along every single wall.
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Every time the map is cut in half, the two halves are added as nodes at the bottom of
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the tree.
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By the end, you're left with a tree where each node at the bottom of the tree represents
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a distinct sub-sector.
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Remember, this tree is entirely conceptual.
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It doesn't actually exist.
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00:18:47,519 --> 00:18:52,920
So long as the planes don't move – vertical movement is accepted from this because vertical
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movement is a separate value – the same BSP tree can be used.
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00:18:57,960 --> 00:19:03,480
Doom's BSP tree generation was done after levels were complete and would search for
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the best possible tree, that being the one that generates the fewest binary tree nodes.
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A binary search is performed to determine what sector the player is in.
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A binary search is when an array of pre-sorted data is searched through by continually halving
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said array.
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A search through a binary tree is, by its nature, a binary search, because every time
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you go down a node, you're removing half of the possibilities.
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00:19:29,079 --> 00:19:33,859
After the player's sector is determined using this binary search, the sub-sectors
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00:19:33,859 --> 00:19:38,279
are then sorted by their distance from the player – closest to furthest.
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00:19:38,279 --> 00:19:42,279
The tree is iterated through to determine which planes to draw.
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00:19:42,299 --> 00:19:47,220
The horizontal scanlines from raycasting are still used to track the parts of the screen
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that have been drawn over.
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00:19:48,859 --> 00:19:53,619
This way they are able to render front to back and ensure that there is no overdraw.
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00:19:53,619 --> 00:19:57,859
When each node is passed over in the iteration, a few things are checked.
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Has that area already been painted over?
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If so, don't bother drawing it.
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00:20:02,339 --> 00:20:08,660
When a plane, polygon or wall is drawn, it is akin to a curtain being drawn left to right.
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00:20:08,720 --> 00:20:14,200
To unveil an area, so to speak, whenever a curtain is seen by the player, it is unveiled
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from closest to the furthest.
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00:20:16,040 --> 00:20:20,759
To be exact, it's the closest 256 walls that are displayed.
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00:20:20,759 --> 00:20:26,240
Remember how height of the pixel columns drawn on screen depended on distance from the player?
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00:20:26,240 --> 00:20:32,120
For Doom, this required determining the angle of both ends of every wall, relative to the
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player's field of view.
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00:20:33,440 --> 00:20:38,580
In the early 90s, most processors didn't have dedicated floating-point capability.
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00:20:38,599 --> 00:20:41,599
This is a float in programming, if you've ever heard of that.
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00:20:41,599 --> 00:20:45,359
Basically a data type for very precise decimal numbers.
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00:20:45,359 --> 00:20:51,659
The Doom engine had to use binary angle measurements, which avoid floats, and used a lookup table
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to determine the x coordinates.
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A lookup table is essentially a cheat sheet.
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00:20:56,960 --> 00:21:02,359
Instead of the processor doing the maths itself, it just looks up the answer in this lookup table.
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00:21:02,359 --> 00:21:08,559
They also used these angles for backface culling, with a simple and elegant piece of mathematics
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00:21:08,559 --> 00:21:14,379
Backface culling basically means the renderer doesn't draw the inside of every polygon.
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It only draws the part on the outside that you actually see.
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00:21:18,099 --> 00:21:23,339
The walls are rendered first as pixel columns from front to back, then the ceilings and
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floors using pixel rows.
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00:21:25,819 --> 00:21:31,500
The objects such as barrels and enemies are rendered from the furthest to the closest.
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00:21:31,500 --> 00:21:37,599
The ceilings and floors are determined using visplane underscore t, or visplanes.
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00:21:37,600 --> 00:21:41,900
Plains were determined using height values within each sector.
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00:21:41,900 --> 00:21:46,940
Visplanes are not constrained to single sectors, and will be continuous provided they all possess
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00:21:46,940 --> 00:21:50,600
the same height, illumination and textures.
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00:21:50,600 --> 00:21:53,180
Pixel rows are drawn top to bottom.
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00:21:53,180 --> 00:21:59,080
One final thing you may wonder about Doom's graphics is why are all the enemies just pictures
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facing towards you?
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00:22:00,780 --> 00:22:04,880
Probably something to do with them being what we call front-facing sprites.
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00:22:04,880 --> 00:22:08,980
They're rendered last, and like I said, furthest to closest.
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00:22:08,980 --> 00:22:11,340
That's the opposite order to the geometry.
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00:22:11,340 --> 00:22:16,340
They are just pictures, taken from the data files and projected onto screen.
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Of course, they're a range of pictures.
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00:22:18,840 --> 00:22:24,020
The one that is drawn depends on the player's location relative to the enemy, and the direction
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00:22:24,020 --> 00:22:25,500
the enemy is facing.
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00:22:25,500 --> 00:22:29,040
The enemies do actually have a full 3D hitbox.
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00:22:29,040 --> 00:22:34,260
The pictures, as most fans know, are actually from real pictures taken of sculptures made
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00:22:34,259 --> 00:22:35,400
by the artists.
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00:22:35,400 --> 00:22:41,519
So, John Carmack was faced with a fierce issue in the problem of visible surface determination.
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00:22:41,519 --> 00:22:46,759
He had to find a solution that was both incredibly fast and very accurate.
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00:22:46,759 --> 00:22:53,000
BSP doesn't completely solve the visible surface determination problem, but it is one
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00:22:53,000 --> 00:22:56,900
of the most reliable and efficient methods of optimisation.
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00:22:56,900 --> 00:22:59,039
It saw massive acceptance.
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BSPs were evolved and made their way into Quake's dramatically improved game engine
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when they took on Michael Abrash and finally figured out the full six degrees of freedom.
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00:23:09,819 --> 00:23:15,220
From there, it was in every FPS, and I mean all of them.
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00:23:15,220 --> 00:23:16,859
Half-Life and Half-Life 2?
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00:23:16,859 --> 00:23:17,859
Every Source game.
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Counter-Strike to Left 4 Dead.
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00:23:19,819 --> 00:23:21,500
The Halo series used it.
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00:23:21,500 --> 00:23:24,579
You know the Scarab from Halo 2 is actually a BSP object?
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00:23:24,579 --> 00:23:27,980
Yes, it's a moving piece of level geometry.
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00:23:27,980 --> 00:23:33,039
Many would say it's a sign of Carmack's genius that he took an idea from concept to
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mainstream solution.
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00:23:34,839 --> 00:23:41,839
He did all this crazy work in between supercharging Ferraris and becoming a judo master.
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00:23:41,839 --> 00:23:44,519
One time, he got locked inside a building.
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00:23:44,519 --> 00:23:49,759
Instead of, say, waiting for security or calling a locksmith, he devised a brilliant solution.
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00:23:49,759 --> 00:23:54,759
He'd luckily gone to a Renaissance Fair earlier, where he bought a medieval battle axe.
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Also, naturally, he smashed down the door with his mighty axe.
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00:23:58,779 --> 00:24:01,539
He was rich so he could afford to get the door fixed.
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00:24:01,539 --> 00:24:07,379
He truly is a unique figure in the gaming industry, and you can see why he's so highly
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00:24:07,379 --> 00:24:08,379
respected.
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00:24:08,379 --> 00:24:12,019
If you made it this far, comment, thank you John Carmack.
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00:24:12,019 --> 00:24:17,700
The use of BSP trees has begun to be replaced over the last few years.
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Developers instead opt for things like static meshes.
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00:24:20,740 --> 00:24:25,620
With more powerful hardware now, they can afford some level of overdraw.
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00:24:25,620 --> 00:24:30,400
Other methods give artists more creative freedom and a much quicker workflow.
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00:24:30,400 --> 00:24:36,420
BSP often leads to the distinct blocky look that many old games had.
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00:24:36,420 --> 00:24:41,839
One could certainly argue that these technical limitations are what gave source maps and
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00:24:41,839 --> 00:24:45,720
early 2000s maps in general their distinct charm.
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00:24:45,720 --> 00:24:47,079
Their soul.
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00:24:47,079 --> 00:24:54,079
With stark and distinct architectural choices, some magic is truly lost in busy modern day
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00:24:54,079 --> 00:24:55,399
maps.
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Many new games have actually tried to go back to recreating these older, cleaner, more distinct
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visuals.
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BSP is still occasionally used today in prototyping levels for games, quickly blocking them out.
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It's of course still used in games such as Counter Strike Go.
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00:25:11,279 --> 00:25:16,000
This was a big video, and naturally it took a bit of research, which I've provided links
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to in the description.
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00:25:17,539 --> 00:25:23,960
If I got anything wrong, please feel free, in fact feel obligated, to call me out in
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00:25:23,960 --> 00:25:24,960
the comments.
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00:25:24,960 --> 00:25:31,359
Like, join the Discord server and subscribe with notifications on to join the nerd army
405
00:25:31,359 --> 00:25:33,000
and become a sigma male.
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00:25:33,000 --> 00:25:34,799
Thanks for watching, goodbye.
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00:26:03,000 --> 00:26:24,680
Bye.
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