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Sephiroth

mystery bug in doom

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there is a bug i have only seen in the original doom engines. it is both in doom1 and 2. This bug is one of the strangest and rarest in the game. I would like to have it explained if anyone knows its secret. Well here is a description. I run into this offten when running a external wad. I have seen it playing the normal game but it has been a long time. Well it is usally a small area that is effected. A small texture, always a wall, is replaced by many colored stripes, or a solid color(usally grey). It then causes the frame rate to drop down to about 2-10 frames/sec. This frame rate drop only happens if it is in visaul range. Also it only effects a few areas and not the whole texture. other spots in the level may use the same texture yet be uneffeced. I have found not documentation on this odd bug. someone please explain what it is, what causes it and how it works

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Huh, I never noticed that.

What I have noticed, however, is that in ZDoom 1.23 b28 the framerate drops when you are near a wall that has lots of blood splats, wall burns, BFG marks, etc. However, it doesn't cause any real problems for me and I move on.

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It is the Medusa effect if it slows down the frame rate...
Following Info from Doom design faq.


From:
DESIGN12.FAQ -- Frequently Asked Questions about DOOM Level Design
---------------------------------------------------
Version 1.2, 09 Sept 1994. Editor: Tom Neff <tneff@panix.com>



[2-4] I wanted to make a doorway that LOOKS like a wall, by taking a
passable two-sided line and giving it a Normal texture on one or both
sides. Then you could walk/shoot through it, hide behind it, etc. But
when I loaded my level and walked up to the secret wall, it looked like
weird colored strings, and my PC slowed to a crawl. What's wrong?

A. We call this the Medusa Effect - it looks like snakes and you turn
to stone. :-) It happens because you used a *multi-patch* texture on
the Normal of your passwall. A fuller explanation of patches and
textures can be found in the Unofficial Specs (see Appendix B), but
briefly, each texture (like STARTAN3) is built from one or more graphic
"patches" (like SW19_1 and SW19_2); and for some reason, DOOM's engine
can only draw SINGLE-patch textures on passable walls. Examples of
single-patch textures (which you could use) are BROWNGRN, SKINTEK2, and
ASHWALL. Examples of multi-patch textures that won't work are STARTAN3,
COMPBLUE, and WOODSKUL. A complete list (TEXPATCH) of textures and the
patches that make them up is available (see Appendix [D-4]).
----------------------

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It's called the medusa effect. It's well known. It's caused by the placement of a texture composed of vertically and/or overlapped patches on the main texture slot of a two sided linedef.

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Another bug thats kina weird but good, is the fact that sometimes pain elementals don't spawn lost souls, even when they die. My theory is that these 'eunech' pain elementals are like this to lessen the amount of objects of the level, which would explain why they seem to only be on levels with large amounts of pain elementals (1.e. The Pit). However, this theory does not hold true on Icon of Sin, where I've never seen one of these inefective monstrosities.

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with the real game, there can ONLY be 20 lost souls on the map at one time.
if there are already 20, then when a PE dies(or attacks), it will not spit any out.

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with the real game, there can ONLY be 20 lost souls on the map at one time.
if there are already 20, then when a PE dies(or attacks), it will not spit any out.

So THAT'S it... weird, I thought it was hard-coded that the first-two you encounter are broken.

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My friend told me that he once encountered a bug on MAP30 where from some reason the Icon of Sin was only spitting out Pain Elementals, but I never encountered this myself.

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I guess it could.

Let's ask this question:

Imagine a plane, which has an X axis and a Y axis.

You pick one (completely random) point. What's the probability that this point will lie on the X axis?

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Depends on liguistics.

That's the old stupid problem that says 50% because it's either IN the axis of OUT of it, right?

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I think it happens when you look at a two-sided linedef with a transparent texture on the sider you're not looking on... At least that's how i remember fixing it in my wad's back in the early doom days.

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I guess it could.

Let's ask this question:

Imagine a plane, which has an X axis and a Y axis.

You pick one (completely random) point. What's the probability that this point will lie on the X axis?



I'm no mathematician, but I at least know the Cartesian coordinate plane.

Anyway, the answer is, oh, almost infinitesimal.

Heh, and that's just on a plane. Imagine the chances of hitting the X-axis if it was SPACIAL! (3-D, with X, Y, and Z axes and 8 quadrants)

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Actually, whether it's on a plane or in 3D space, the chance is the same: 0. It's defined as 0 because it's smaller than any number you may imagine.

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