DEH for ability to see VPO (numvisplanes>128) with doom2+

[entryway]

Only for doom2-plus-1.92.6

Usage: apply this DEH for doom2p.exe, start any pwad with hacked exe, activate pistol. If AMMO is 0 in statusbar - there was no overflow of 'vanilla' visplanes limit (MAXVISPLANES = 128)

Patch File for DeHackEd v3.0

# Note: Use the pound sign ('#') to start comment lines.

Doom version = 19
Patch format = 6

Weapon 1 (Pistol)
Ammo type = 124732

Already patched doom2p.exe and show_vpo.deh:
http://prboom-plus.sourceforge.net/doom2p_show_vpo.zip

[esselfortium]

O_O

....HOW?!

[entryway]

esselfortium said:

....HOW?!

With "Ammo type" overflow it's possible to see any memory value in AMMO part of statusbar.

124732 = (0x100000 + 0x298 * 128 - 0x9AF14) / 4 + 1

0x100000 - address of visplanes table from doom2+
0x298 - size of one visplane (sizeof(visplane_t))
128 - MAXVISPLANES from doom2.exe
0x100000 + 0x298 * 128 == &visplanes[128]
0x9AF14 - address of players[0].ammo[0]
+1 is for visplane_t::pichum instead of visplane_t::height

Thus, address of players[0].ammo[124732] actually is equal to address of visplanes[128].picnum which is initialized to 0 at start.

[myk]

Ah, see, VPOs are a good thing now... they give you ammo!

(This should be useful while testing Doom levels from the DOS prompt.)

[fraggle]

Cool hack!

[Mechadon]

Wow, amazing :O

[printz]

What if vanilla mods appear, replacing gun slots with various indicators?

Heh heh. Not even CHOCOLATE DOOM will work with them!

[Gez]

PROTIP: When visplanes overflow, shoot at them until they die.

[entryway]

printz said:

Heh heh. Not even CHOCOLATE DOOM will work with them!

But you can try this in Choco:

Patch File for DeHackEd v3.0

# Note: Use the pound sign ('#') to start comment lines.

Doom version = 21
Patch format = 6

Weapon 1 (Pistol)
Ammo type = 12

Will give you one bullet for every killed monster (14 for secrets count). Works in prb+ 2.5.0.4.test too.

[cybdmn]

This is by far the greatest dehacked patch i've ever seen.

[printz]

Oh. I can finally make necro weapons in vanilla or chocolate Doom! (soul cube for Doom 1 -- yet gotta resolve the restoration part...)

[Redneckerz]

Holy omega bump:

A bump of this magnitude obviously needs merit. Luckily, i believe this one does.

 

The story so far:

The OP's original link has been in absentia for numerous years (dead link). Knowing that @entryway still visits this place, i decided to put on my Dooming shoes and do an enquiry regarding this (and something else, but that's for later). He lost the actual executable.

The story continues:
Even though one could patch this themselves given the patch was directly posted, Entryway did a most generous thing:

Spoiler

''Ok, I've applied that deh to doom2p.exe and uploaded with the same link:

http://prboom-plus.sourceforge.net/doom2p_show_vpo.zip

''

Some testing:

• Entryway recreated the DEH (From the page) and then crafted a Doom-2Plus executable out of it.
• The executable is called DOOM2PSV.EXE.
• Tested it with Astro.WAD. Gave a nice 0 back as a reading.

So now we have a working link again and a unique tool to detect VPO's. I reckon this is most useful for vanilla mappers and editors like @Doomkid, @fraggle, @Linguica, @esselfortium and @JadingTsunami for instance.

More lost Entryway obscurities are to come but ill put that in a seperate thread.

Edited January 24, 2021 by Redneckerz

[Doomkid]

Oh wow, this seems like a great way to hunt down VPOs! Thanks for the bump.