[Status] Understanding Poison

[Shade]

Hi,

 

I'm trying to reduce the limit of poison damage from 25% to 10% but I couldn't get myself to understand what is going on the status.c:

case SC_DPOISON:
// Lose 10/15% of your life as long as it doesn't brings life below 25%
if (status->hp > status->max_hp>>2) {
int diff = status->max_hp*(bl->type==BL_PC?10:15)/100;
if (status->hp - diff < status->max_hp>>2)
diff = status->hp - (status->max_hp>>2);
if( val2 && bl->type == BL_MOB ) {
struct block_list* src = map_id2bl(val2);
if( src )
mob_log_damage((TBL_MOB*)bl,src,diff);
}
status_zap(bl, diff, 0);
}
case SC_POISON:
// Fall through
val3 = tick/1000; // Damage iterations
if(val3 < 1) val3 = 1;
tick_time = 1000; // [GodLesZ] tick time
// val4: HP damage
if (bl->type == BL_PC)
val4 = (type == SC_DPOISON) ? 2 + status->max_hp/50 : 2 + status->max_hp*3/200; 
else
val4 = (type == SC_DPOISON) ? 2 + status->max_hp/100 : 2 + status->max_hp/200;
break;

I don't get what the if condition means:

if (status->hp > status->max_hp>>2) {

Shouldn't it be:

if (status->hp > status->max_hp*1/4) {

Looking forward to gain a better understanding of this.

 

Thanks,

Shade

[nanakiwurtz]

Hello Shade!

The source code sometimes is easier to work with binary.

To make you understand better, I have an example for you:

Let's say that a player's Max HP is 10000, in binary it's 100111000100.

Then we want to make it to 25%, so we just shift it right, twice, so: 100111000100 will becomes 1001110001 which is 2500.

And 2500 is 25% of 10000 right?

 

But then again, you may ask, "Why do I have to shift it twice? (>>2)"

Well it's because 2500/10000=0.25 (25% from 10000) --> 1 / 0.25 = 4 --> 4 is 2^2

 

It would work too just like what you have said earlier "max_hp*1/4".

But, what if your player's Max HP is 9999?

A --> Decimal calculation: 9999*1/4 = 2499.75

B --> Binary calculation: 10011100001111 -> 100111000011 = 2499

 

Since our rA engine doesn't work with floating numbers, then it'll take another steps to omits the decimals from calculation A, but what happened with calculation B? It automatically omits the decimals isn't it?

That's why I said that working with binary is easier...

 

But in this case what you want is "status->max_hp/10" since you want 10% of the Max HP ^^

Edited March 30, 2014 by nanakiwurtz

[Shade]

@nanakiwurtz

 

Now that made more sense. Haha. Thank you.

 

But surprisingly, no matter what condition I put into it will always stop at 25% HP. I'm not sure why.

[nanakiwurtz]

@nanakiwurtz

 

Now that made more sense. Haha. Thank you.

 

But surprisingly, no matter what condition I put into it will always stop at 25% HP. I'm not sure why.

To put new code into effect, you have to recompile your server

[Shade]

Well, yes I always recompile servers after doing SRC edits. I've been doing a lot of SRC edit for skills to gain better understanding and so far most of it works like a charm except this poison status. 

[Kichi]

Find this:

status.c

map_freeblock_lock();
	if(status->hp >= max(status->max_hp>>2, sce->val4)) //Stop damaging after 25% HP left.
		status_zap(bl, sce->val4, 0);

Change to

 

map_freeblock_lock();
		if(status->hp >= max(status->max_hp/10, sce->val4)) //Stop damaging after 10% HP left.
		status_zap(bl, sce->val4, 0);

[Shade]

 

Find this:

status.c

map_freeblock_lock();
	if(status->hp >= max(status->max_hp>>2, sce->val4)) //Stop damaging after 25% HP left.
		status_zap(bl, sce->val4, 0);

Change to

 

map_freeblock_lock();
		if(status->hp >= max(status->max_hp/10, sce->val4)) //Stop damaging after 10% HP left.
		status_zap(bl, sce->val4, 0);

I did that, recompiled, still stays @ 25% max hp.