[Potato Uno]

Title says above.

How does one detour an in-game function to execute some other code rather than the one Valve has set it to execute?

So rather than function A executing instructions 1, 2, 3, 4, 5 and return 0.2 (as written by Valve), make function A execute instructions 6, 7, 8, 9 and return 0.3 (written by me or someone else).

Is there a tutorial or some methodical way to do this? I'm assuming an SM extension would be required to do this?

[Chdata]

use DHooks

[kadet.89]

Here is a simple example for beginners:
https://forums.alliedmods.net/showthread.php?t=159876

[pheadxdll]

Use dhooks or sourcehook for hooking virtual functions. They modify the vmt leaving the original function unchanged.
Use CDetour for everything else (static/member functions). They modify the first few instructions of the function to perform the hook.

These two things are what 99% of extensions do.

[WildCard65]

Originally Posted by pheadxdll Use dhooks or sourcehook for hooking virtual functions. They modify the vmt leaving the original function unchanged. Use CDetour for everything else (static/member functions). They modify the first few instructions of the function to perform the hook. These two things are what 99% of extensions do.

SourceHook and CDetour are what extensions use, DHooks is a wrapper of SH I believe(I'm not 100% sure but I'm pretty sure) for plugins to interact with it.

[asherkin]

Originally Posted by Chdata use DHooks

If it's a virtual function, use DHooks and avoid the pain of writing / maintaining (where the real pain is) an extension.

There is a tutorial here: https://forums.alliedmods.net/showthread.php?t=191171

[Potato Uno]

What's with people saying extensions are so painful? Can I have a couple of reasons WHY they are painful? Using TF2Items for example it only broke like 3 times this year, whereas gamedata went stale like 10 times (or more).

If extensions are truly painful then I might not even want to bother dealing with them lol.

Also how do you know if a function is a virtual function?

[asherkin]

Originally Posted by Potato Uno What's with people saying extensions are so painful? Can I have a couple of reasons WHY they are painful? Using TF2Items for example it only broke like 3 times this year, whereas gamedata went stale like 10 times (or more). If extensions are truly painful then I might not even want to bother dealing with them lol.

TF2Items has 5 years of experience and the entire AlliedModders build infrastructure behind it, it's in maintenance mode only and requires absolutely no manual work to build - just push a commit and a download for each package magically appears within 10 minutes. You're not going to have this.

Originally Posted by Potato Uno Also how do you know if a function is a virtual function?

See if it has a reference from a vtable (and only from a vtable).