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Calculating a result based on a given percentage

by Jacob · in Technical Issues · 09/19/2005 (6:05 pm) · 6 replies

I am trying to figure out how to do this...

For example, I would like to determine the success of an action that the player attempts, based on some skills, which when eveluated will provide a "percentage chance of success". So I thought that I could just do the following:

%chance = 82;  // percent chance

%rand = (100 / %chance);  // 1.2195

%success = getRandom(%rand);

if(%success == %rand)
   return true;  // success!
else
   return false;

Now this would work if %chance is something like 50, 10 or 2 but being 82, things don't work out as planned because %rand becomes a float.
Even if I rounded %rand to a whole number, the result wouldn't be correct/precise. Any ideas?

Edit: As you can see, getRandom will return 0 or 1, making the success of the action 50% and not 82% as desired.
If I do this:

%success = getRandom(1, %rand);

I will always get a 1, making it 100% - also not what I want :)
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Torque Owner Scott Casey
#1
09/19/2005 (6:34 pm)
You want a less than or equals to operator, otherwise you only have a 1% chance at hitting 82.

Torque 3D Owner Jacob
#2
09/19/2005 (7:04 pm)
Edit: I see how you got that...I had 
%rand = 100 // %chance;

but it should have been

%rand = (100 / %chance);

I changed my first post - does my question make more sense now?

Torque 3D Owner Jacob
#3
09/20/2005 (5:13 am)
I figured out what Scott was saying now - all is well. Thank You!

Edit: spelling

Associate Manoel Neto
Default Studio Name
#4
09/20/2005 (6:37 am)
Maybe it can also be done in this way:

%change = 82;
%rand = getRandom(1, 100);
if (%rand <= %change)
   return true;
else
   return false;

Torque Owner Dracola
#5
09/20/2005 (7:24 am)
Yes Manoel's method would work.

Torque 3D Owner Jacob
#6
09/20/2005 (7:40 am)
Thats what I figured too, it's interesting how these things come to me after I post a question :) - anyway, thanks!