[Fixed] Proximity of things to walls

Post by **Kappes Buur** » Wed Aug 06, 2003 8:56 am

I am not sure if that subject had come up before.

In Heretic, the torches were regularly attached right to the walls.

However, ZDoom does not display them properly.

Moving the mouse, just slightly, back and forth, the torches blink in and out or sometimes are not displayed at all.

Anonymous · Post by **Anonymous** » Wed Aug 06, 2003 10:03 am

I've noticed that myself. Good example: E1M1. You start off looking straight ahead, and there's the part where the ceiling lowers and there are the two torches on the wall there, right before the outside part. In Heretic.exe they're there, but not in ZDoom.

randomlag · Post by **randomlag** » Wed Aug 06, 2003 10:12 am

I just tested E1M1 can't see it (clipped through the level - pretty sure I looked at them all).

However, the torch is right ON the line (not 100% sure since there's no cross for the center). The torches in Heretic are slightly OFF the wall. As I recall, even in Heretic this causes the exact same problem.

[Edit, well I missed the most obvious one

Still that was a problem in Heretic and putting them right ON the line is not a good idea because of the ambiguity presented.]

PS. When I moved the E1M1 torch 1 unit over, it's all fine.

HotWax · Post by **HotWax** » Thu Aug 07, 2003 2:29 pm

The wall is being rendered in front of the torch.

Post by **randi** » Thu Aug 07, 2003 8:48 pm

ZDoom's renderer is not the same as Doom's. Because of imprecision, a sprite that lies directly on a line will sometimes be behind the line and sometimes in front of it when it gets projected to the screen. Raven really shouldn't have made levels with sprites positioned like that.

Post by **Xaser** » Thu Aug 07, 2003 9:06 pm

randy wrote:Raven really shouldn't have made levels with sprites positioned like that.

So that means it's not really a zdoom bug, then. Problem solved. Well, sort of.

HotWax · Post by **HotWax** » Fri Aug 08, 2003 10:14 am

With this being a display bug only, and not a game-killer in any way shape or form, I definately wouldn't advise breaking or hacking the engine to make it compatible with poorly made maps.

Post by **Graf Zahl** » Fri Aug 08, 2003 1:39 pm

HotWax wrote:With this being a display bug only, and not a game-killer in any way shape or form, I definately wouldn't advise breaking or hacking the engine to make it compatible with poorly made maps.

I fully agree. Maybe a solution as in the Doomsday engine which moves the torches out of the walls is the best (although even that doesn't handle all torches correctly).

Ultraviolet · Post by **Ultraviolet** » Fri Aug 08, 2003 4:54 pm

Or maybe Doomsday just has some poorly hacked solution that gives sprites close to lines a certain margin for draw-order preference... like, if it's within 1 unit of the line that sprite gets drawn after the wall or something.

Post by **Kappes Buur** » Sat Aug 09, 2003 12:10 pm

I just remembered the original thread in the old phorum, where this rendering imprecision had come up with the barrel, half burried in a wall, in Doom2 map02.

I had a closer look, again, at that and noticed that anything placed directly onto a linedef, when the two adjoining sectors are of differing heights, that the thing will be rendered with some flaws.

This is the same area in Doom2 map02 as the above, but the opposite wall.

So, the moral of the story is, I guess: Do not place things directly on a linedef!

Maverick · Post by **Maverick** » Sat Aug 09, 2003 4:01 pm

Actually, many of the barrels in that area of the map show some rendering problems (from certain angles), and they don't appear to be directly on any lines.

Regards,

Maverick

Post by **Graf Zahl** » Sun Aug 10, 2003 3:01 am

Ultraviolet wrote:Or maybe Doomsday just has some poorly hacked solution that gives sprites close to lines a certain margin for draw-order preference... like, if it's within 1 unit of the line that sprite gets drawn after the wall or something.

No, it has some code to actually move them out of walls. For most torches it works fine but sometimes it screws up. That's because it uses the torch's sector links instead of the blockmap to determine where to move it and this doesn't always find the right wall.

Hirogen2 · Post by **Hirogen2** » Wed Aug 13, 2003 3:03 am

Putting a sprite directly on a linedef would -- in 2D as in 3D space -- violate
the space continuum. Two objects cannot exist at the same point. At least not
right now.

HotWax · Post by **HotWax** » Wed Aug 13, 2003 2:27 pm

Hirogen2 wrote:Putting a sprite directly on a linedef would -- in 2D as in 3D space -- violate
the space continuum. Two objects cannot exist at the same point. At least not
right now.

So you're saying it's not possible to place your couch in any position where it would cross from one type of floor (e.g. carpeting) onto another (e.g. wood flooring)? Fascinating....

Hirogen2 · Post by **Hirogen2** » Fri Aug 15, 2003 2:55 am

Nah I mean if I had two equal cubes, they could not exist at the same position at the same time, except if there is some weird physics.