is it incorrect to use:
value = value - FOO

I imagine you'll find instances of this in the old code only in places where they knew 100% that the bit was set, so just needed to subtract it.

Even so, it's still always better to use
value = value - (value & FOO)

because it shows the coder intent. 

if you know that its already set then just subtracting it is fine... 

After killing something,it drops a weapon,out of which some can be picked-up.Just like AD but with vanilla QC code.How do I get this?

I tried adding rubicon2's code for g_axe and g_shotgun in my mod but it didn't work.So now I am starting with a clean source in a few days,how do I make this code from scratch?

Is there a shortcut way to add frames for a monster in qc? I heard it was there in some tutorial online but I can't find it. 

Maybe start from checking out DropBackpack in items.qc 

Like khreathor says,
when the mod drops a backpack, it spawns an entity, (with a timer to remove it).
To drop a gun seperate from the pack, like the gun in hand with *some* ammo, you need to spawn a new entity, with a PRECACHED model. and give that entity a .ammo amount, and create a touch function for that gun-entity.
I had done this once long ago. I will dig up some code and try to point you to your goal.
It only helps you to become a better coder with hints and not code cut/paste. But I can give you a detail list of what you need to get this working. 

Not exactly what you want but you may find some of the coding useful to get what you are after:-

http://www.insideqc.com/qctut/qctut-60.shtml

http://www.insideqc.com/qctut/lesson-10.shtml 

does anyone know why IDsoftware made the trace for the lg start at the feet not +16?
```
org = self.origin + '0 0 16';

traceline (org, org + v_forward*600, TRUE, self);

WriteByte (MSG_BROADCAST, SVC_TEMPENTITY);
WriteByte (MSG_BROADCAST, TE_LIGHTNING2);
WriteEntity (MSG_BROADCAST, self);
WriteCoord (MSG_BROADCAST, org_x);
WriteCoord (MSG_BROADCAST, org_y);
WriteCoord (MSG_BROADCAST, org_z);
WriteCoord (MSG_BROADCAST, trace_endpos_x);
WriteCoord (MSG_BROADCAST, trace_endpos_y);
WriteCoord (MSG_BROADCAST, trace_endpos_z);

LightningDamage (self.origin, trace_endpos + v_forward*4, self, 30);
``` 

First thing to note is that the player's self.origin is at crotch level, not feet level. However, you are correct that the visual beam projects from a height of 16 units above the damage beam.

The sad truth is that the lightning bolt code is kinda buggy, and that's not even the worst bug. If you look through LightningDamage you'll notice it performs 3 traces in a row. The intent seems to be making the beam wider and allowing it to hit multiple enemies in the path. In fact, the vector calculations for the 2nd and 3rd are completely wrong, and the beams just fire into parts of the level that can't be seen by the player.

The buggy extra beams do fire in a way that is predictable based on the player's origin and facing angle. The following video shows a speedrun which exploits this! At about 50 seconds in, the player rides a lift down, faces in a very specific direction, and starts shooting the Thunderbolt. The specific location and direction of the shot causes a second beam to hit the Shalrath at the end of the level, which kills it before the doors open. This lets you grab the rune early, speeding up the run...

https://www.youtube.com/watch?v=D_P35WtpAwY 

origin is at crotch level

So that's realistic then. 

Sounds like a fast 4 wheeler.

Anyhow, is there a fixed version of the code somewhere? 

I need to keep this thread at the top of the forum!
Someone please make this a permanent thread! 

org not origin 

help guys:
I'm trying a Q1 total conversion(a true one! as Carmack stated in gpl readme) and I created my monsters totally re-skinning the standard knight model in qme.
So,in a supposed commercial release, may I use them also with the knight animations left untouched in qme ?
-my monsters don't resemble id original in any way and after all animations frames are only numeric values in qme not copyrighted assets I guess- 

Lets you sell the stuff too. 

Engine and game code are GPL, the content is not. Even with a new skin, it's still the original model. You'd have to create a new one from scratch. 

..qc code:
qc code is free to use and from what I saw animation frames are also listed in it so what ? 

When you say "skin" do you mean the texture or the model? At some point the word "skin" transitioned from originally meaning just texture to meaning the whole thing - texture AND model.

If your model is a completely new model built from scratch then I imagine it's fine in a commercial release. 

'may I use them also with the knight animations left untouched in qme'
if you started with the knight model in qme, then the result is still a derivative work in some small way, and still subject to id's copyright.
strictly speaking such derivative works (note that this includes maps that just contain id's textures) should not be distributed at all, but we usually do so anyway on the understanding that the recipient has the full version of quake. I believe we follow that interpretation thanks to someone at id saying it'd be okay despite not being stated in the license, but I can't prove that sadly.
you may also be able to get by on fair-use laws, depending on legal jurisdictions... so you can probably get away with loading up the model and deleting the skins+verticies+triangles. names and sizes of frames+skins is probably okay under fair use, but sticking to those frame numbers means that your resulting model is probably going to play back at the wrong speed or something stupid/ugly like that, so its not something that's really worth much anyway.

the sources for the maps was also released (under the gpl) a while back, but combining that with the vanilla textures is arguably a violation of the gpl!

if you want a _total_ conversion, then delete pak0.pak and pak1.pak from your harddrive...
(and use a different palette... if only because quake's sucks...) 

I wonder what is minimum PAK content to run engine?
I guess palette, sprites to run MENU, start map, what else? 

gfx.wad

Should be it I think. 

dp+fte will both start up with absolutely nothing, depending on your definition of 'start'.

FTE:
for instance, if fte can't find id1/pak0.pak (or equivalent) then it'll not know what sort of game its meant to be running nor which gamedirs it should use. you can get it to behave with -basedir . -quake -nohome and it'll get the idea then. alternatively put fteqw.exe+default.fmf in the same dir and you can get the same effect without commandline args (possibly with other gamedirs instead, no id1).
if there's no [qw]progs.dat then fte will fail to spawn any entities. however, it will still load the world, the PutClientInServer function will fall back to spawning the player with noclip, and the various other missing functions will be ignored. The result is that you can at least view maps with nothing but the engine and a bsp... (and one of those 3 ways to get the filesystem code to be happy).

DP:
dp tends to have extra dll dependancies. I don't know if it'll cope without a progs.dat, but it should be fine if you give it a progs with just entity self;.float movetype;void()PutClientInServer={self.movetype=8;};
or you can just compile some gpled progs. obviously this isn't needed if you're just running it as a client.

QuakeSpasm/Other:
ignoring dll dependancies, other engines will definitely need some gfx.wad, for the palette lump, the colourmap(in sw renderers) lump, conchars lump, the various sbar image lumps (apparently quakespasm doesn't need those any more). They'll also need a gfx/conback.lmp, in most cases a gfx/pop.lmp (so they actually allow loading files without the demo's pak0.pak - this file can be generated correctly from the engine source which defeats the point of the check for it). annoyingly they'll also need a player.mdl (player baselines expect it, use a renamed spr or bsp if you want). any menus that are displayed (most noticeably the main menu) will need their images to load in order to avoid sys_errors.
you'll need a progs.dat if you're running it as a server. You'll need to provide everything up to end_sys_fields without reordering etc. this will also include a few functions which will need bodies, though they can be empty (you'll probably want at least the noclip thing though).
you'll also need a map, presumably.
those are the files/lumps that I can think of. 

..to run Quake, so better leave them there.
As for my TotalConversion project, do ya think a single person could bear all the load of work needed ?
I'm relatively good at creating textures, levels, models.. even weapons(aarrrgh!), but I fall short on fx sounds and AI code for example :(
AI is an intangible thing so how could people be aware if I use IDsoftware one ? 

I found this thread about minimum code in QuakeC too: http://quakeone.com/forums/quake-talk/quake-central/11506-quakec-developer-tools.html

...but I think writing everything from scratch is kinda tedious task. 

Quake's AI uses a set of think functions for various behaviours: th_run, th_stand, th_die,etc.

These functions start a chain of frame functions: void run1 [0] () { ai_run (<somedistance>)}, void run2, run3 etc.

Each function in the chain references a frame number in []'s.

The ai_run, ai_walk, ai_slide, etc. within each chain function moves the enemy by the set distance so that the monster can move realistically with its steps. For instance, at a frame where a foot touches the floor, you might not have an ai_run function or the ai_run will have a small value so the monster stops or slows with its steps.

Other functions do other actions timed with that frame in the animation.

Study the qc source for reference. 

Is there a documentation for the QuakeC opcodes? I'm planning to write a small compiler for something less crappy than QuakeC.