Shock Value

5th June 2003 00:50 UTC

2D rotation problem
Quick question. Shouldn't ...

theta=pi*cc/2;

d=sqrt(x2*x2+z2*z2);

r=atan2(x2,z2)+theta;

x2=d*sin(r);

z2=d*cos(r);

... and ...

theta=pi*cc/2;

ct=cos(theta);

st=sin(theta);

x2=x2*ct-z2*st;

z2=-x2*st-z2*ct;

... do the exact same thing? I thought so, but the second one seems to be acting differently (in other words messing my whole scope up).

EDIT: Figured it out. I just needed to make new variables in place of x2 and z2 instead of using them over. Not sure why I would have to do this with the second method and not the first though.

Would a mod be kind enough to lock/delete this thread?

dirkdeftly

5th June 2003 04:03 UTC

...
x2=x2*ct-z2*st;
z2=-x2*st-z2*ct;

you're altering x2, a term used in the z2 statment, before you get to the z2 statement. to get it to work properly use different variable names, or a storage variable:
x3=x2*ct-z2*st;
z2=-x2*st-z2*ct;
or
x2a=x2; x2=x2*ct-z2*st;
z2=-x2a*st-z2*ct;

Shock Value

5th June 2003 23:36 UTC

Aha, thanks for pointing that out, Atero. And to anyone who cares, my second pack should be done soon.

dirkdeftly

6th June 2003 00:36 UTC

you do mean third pack, right? i could swear i've already got two on my comp...yep, i do....

sidd

6th June 2003 01:07 UTC

me too: onTV and Pixels..