17 comments
Some related content from Youtube channel "Matt's Ramblings":
Quake's PVS: A hidden gem of rendering optimization: https://www.youtube.com/watch?v=IfCRHSIg6zo
How Quake's software renderer ELIMINATES overdraw: https://www.youtube.com/watch?v=zdXsHWHxeBY
I added portals into software Quake: https://www.youtube.com/watch?v=kF-7Jd37gYk
Some additional points of interest: Quake level designers could use "hint" brushes to help the BSP compiler determine where to create cells. Starting with Quake II, designers were able to place "area portals" which are portals programmers could toggle at runtime (think disabling a doorway portal when the door is closed).
Interesting. I recall Prey being the first game to hype portals for rendering, though I think theirs may have been for drawing not just culling? Does anyone know how it worked?
Dark Forces apparently also used portals for culling, IIRC.
No. Prey was one of the first games to hype portals and non-euclidean maps for gameplay.
Portals for rendering date back to the dawn of 3d graphics and many early FPS engines used the concept.
But these portals were only there as a rendering optimisation. While you could abuse them to make non-euclidean maps, the tools were intended to make proper maps, and the portals would be invisible to players.
Marathon 2 by Bungie also had weird non-euclidean maps with overlapping sections in the late 90s I think.
I miss the customizability of that game. Early bungie works were up there with early blizzard or early valve. They sold a tool for fun instead of casting a bait for profit.
[delayed]
> Dark Forces apparently also used portals for culling, IIRC.
DF used BSP for culling. But, I made a mod level long ago playing with features and made a stairway in the middle of a room that you could only see from in front of it. It was some kind of free-standing portal with no surrounding support.
Fun fact: the creator of the DF engine told me he based it on a reverse engineering of a beta release of DOOM. Apparently, the final release of DOOM cut a lot of engine features to gain speed. But, DF shipped with them and maybe a few more.
> Fun fact: the creator of the DF engine told me he based it on a reverse engineering of a beta release of DOOM.
Can you provide a source? As I understand it DF is based on the (pre release?) Tie Fighter engine, and DF began production before Doom released. That's why for example DF has some non-textured 3D models like the turrets and mouse droids. I follow The Force Engine (reverse engineered fan port) and Dev Game Club (hosts worked at LA).
Supposedly DF devs did see Doom (perhaps even a pre release version), but already had their own tech working by that point.
> Apparently, the final release of DOOM cut a lot of engine features to gain speed.
Doubt. There's a lot of interviews with the ID guys, and I don't recall anyone saying they cut significant technical features. They made Doom in only 13 months, minus almost a month to port Wolf3D to SNES. Maybe Carmack -- or the released alphas and betas -- can clarify? Or perhaps you are confusing some of the Doom porting efforts, which did cut down levels and sometimes features significantly.
I think Build used some form of portals as well... primarily for water/underwater transitions, but there was at least one level in Duke3d that used it for some non-euclidian geometry.
E2L11 “Lunatic Fringe.” The map has an outer ring containing 720 degrees of hallway. Surprisingly disorienting even when you know that’s what’s going on.
Pretty sure water was just a teleporter? You may be thinking about the mirror effect? I think that was a kind of a portal effect. You had to make a large empty section behind each mirror that was used by the engine to render a mirrored copy of things in front of the mirror.
You could make some weird impossible geometries by just superimposing sections. Two sections could occupy the exact same coordinates, but movement and rendering were done across edges shared by sections and did not care about if there was some other section in the same space. As long as there was never a way to see those sections at the same time.
Pretty sure water was just a teleporter? You may be thinking about the mirror effect?
That's what they just said? They didn't mention the mirror effect? The mirror effect was done with duplicate geometry? It occupied the overlapping space of what was behind it? The build engine also didn't have vertical levels.
Shadow Warrior (Build) did have some room over room stuff. But IIRC it still leveraged offset sectors like Duke's water. FWIW some modern Doom ports appear to have this as well, at least with levels that support it.
Descent used portals
Acknowledge splitgate 2
This makes me really want to play quake 3 with a portal gun