 | | | expressions question | expressions question 2004-05-25 - By kim aldis
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you appear not to have anything that factors in the radius of your ball.
This expression may have been correct for one ball but have the sizes of you
balls (snicker) changed?
. The correct expression should be:-
posx = 2 * rotx * radius
where rotx should be radians, not degrees. You may need to convert.
conversely:-
rotx = posx/(2*radius)
again, rotation is in radians.
__ __
From: owner-xsi@(protected) [mailto:owner-xsi@(protected)] On Behalf Of
alex dinnin
Sent: 25 May 2004 12:30
To: xsi@(protected)
Subject: expressions question
For years, when translating a sphere. I have applied an expression so that
as it moves in z space it rotates in x... thus rolling along the floor....
this is the expression I have used..
Editing expression on: SPHERE1.kine.global.rotx
Valid expression : SPHERE1.kine.global.posz * 36
As I have never had to go to close up... I have never noticed that this is
actually wrong !!! and that on close inspection.. the translation of ball in
relation to the rotation is wrong.. the ball is sliding !!!
could anyone point me in the right direction please !!!!
Alex
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<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2>you appear not to have anything that factors in the radius
of your ball. This expression may have been correct for one ball but have the
sizes of you balls (snicker) changed?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2>. The correct expression should be:-</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2>posx = 2 * rotx * radius</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2>where rotx should be radians, not degrees. You may need to
convert.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2>conversely:-</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2>rotx = posx/(2*radius)</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=500011612-25052004><FONT face=Arial
color=#008080 size=2>again, rotation is in radians.</FONT></SPAN></DIV><BR>
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style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #008080 2px solid;
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<FONT face=Tahoma size=2><B>From:</B> owner-xsi@(protected)
[mailto:owner-xsi@(protected)] <B>On Behalf Of </B>alex
dinnin<BR><B>Sent:</B> 25 May 2004 12:30<BR><B>To:</B>
xsi@(protected)<BR><B>Subject:</B> expressions question<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>For years, when translating a sphere. I have applied an expression so
that as it moves in z space it rotates in x... thus rolling along the
floor.... this is the expression I have used..</DIV>
<DIV> </DIV>
<DIV><FONT size=2><FONT size=2><FONT size=2>
<P><STRONG>Editing expression on: SPHERE1.kine.global.rotx</STRONG></P>
<P><STRONG>Valid expression : SPHERE1.kine.global.posz * 36</STRONG></P>
<P>As I have never had to go to close up... I have never noticed that this is
actually wrong !!! and that on close inspection.. the translation of ball in
relation to the rotation is wrong.. the ball is sliding !!!</P>
<P>could anyone point me in the right direction please !!!!</P>
<P>Alex</P></FONT></DIV></FONT></FONT>
<P>
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