Problem MeshgroupTransform no 3-axis rotation ?

Mindblast

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I'm trying to do some manual animations using clbkAnimate and manipulating my meshgroups with MeshgroupTransform. I noticed the following: When i try to do a rotation around an axis vector that has 1 or 2 of its components set to nonzero the rotation works, if i use a vector that has all 3 components nonzero the rotation is not carried out. Semi automatic animations using MGROUP_ROTATE and AddAnimationComponent etc. don't seem to have this problem. Has anyone had the same problem? Might be a bug in the API i think. (I just tested this with the 2006 release, not with the current beta)

---------- Post added at 10:45 AM ---------- Previous post was at 09:37 AM ----------

Just tested it in the beta and i have the same problem there.
 

Urwumpe

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Did you remember making sure that the rotation axis vector has to be normalized?

I can't remember ever having had such problems.
 

Mindblast

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Yes i tested it with _V(0.577350269, 0.577350269, 0.577350269) for the axis vector. With the semi automatic animation it works, with MeshgroupTransform it does nothing, whereas if i use _V(0.707106781, 0.707106781, 0) it works both ways.
 

martins

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Looking at the code, you are correct. Rotation around a general axis is currently not supported with MeshgroupTransform. I have regarded this method as somewhat obsolete with the arrival of the animation component mechanism using the MGROUP_TRANSFORM classes, so I never updated the transformation code for MeshgroupTransform. If this is still regarded useful, I can try to bring it up to date for the next beta.
 

Mindblast

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It would certainly be useful for me. I'm trying to do a somewhat complicated landing gear animation with inverse kinematic like features (pneumatic cylinders and such) so i decided to use the clbkAnimate method for better control of the non-linear rotations. I probably could have done it with the MGROUP_TRANSFORM too but i had the impression it would have been more complicated.

Maybe you could make a MeshgroupTransform like function that takes a MGROUP_TRANSFORM pointer as a parameter just like AddAnimationComponent does ? So the MESHGROUP_TRANSFORM structure could go obsolete.

---------- Post added at 03:26 PM ---------- Previous post was at 03:06 PM ----------

Hmmmm.. actually now looking at the documentation for MGROUP_TRANSFORM and AddAnimationComponent.. maybe i was wrong.. especially being able to track Vectors through the animation would simplify things alot for me as i do that manually now. I guess i'll rewrite my code to use this.. so never mind Martin. :)
 

JLBarnes

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Workaround to do 3 axis MeshgroupTransform

This is a little bit of code to fix the problem if you still need to use MeshgroupTransform

bool MeshGroupRotate(VESSEL2 *vs, VISHANDLE vis, MESHGROUP_TRANSFORM &mt)
{
// Test to see if speacial code needed to over come bug is needed
if(mt.P.rotparam.axis.x!=0 && mt.P.rotparam.axis.y!=0 && mt.P.rotparam.axis.z!=0)
{
// calculate the angle of the axis from the xz plane
double tmp_angle;
if(mt.P.rotparam.axis.x>=0.0 && mt.P.rotparam.axis.y>=0.0)
tmp_angle=atan2(mt.P.rotparam.axis.x,mt.P.rotparam.axis.y);
else
if(mt.P.rotparam.axis.x>=0.0 && mt.P.rotparam.axis.y<0.0)
tmp_angle=PI-atan2(mt.P.rotparam.axis.x,-mt.P.rotparam.axis.y);
else
if(mt.P.rotparam.axis.x<0.0 && mt.P.rotparam.axis.y<0.0)
tmp_angle=atan2(-mt.P.rotparam.axis.x,-mt.P.rotparam.axis.y)-PI;
else
if(mt.P.rotparam.axis.x<0.0 && mt.P.rotparam.axis.y>=0.0)
tmp_angle=-atan2(-mt.P.rotparam.axis.x,mt.P.rotparam.axis.y);
// save the existing axis and angle
VECTOR3 save_axis=mt.P.rotparam.axis;
float save_angle=mt.P.rotparam.angle;
// create the two new axis vectors
VECTOR3 temp_axis={sqrt(save_axis.x*save_axis.x+save_axis.y*save_axis.y),0.0,save_axis.z};
VECTOR3 z_axis={0.0,0.0,1.0};
//temp_axis=NormalizeVector(temp_axis); No need to normalize it is already normalized.
// first rotate to the xz plane
mt.P.rotparam.angle=(float)(-tmp_angle);
mt.P.rotparam.axis=z_axis;
if(!vs->MeshgroupTransform(vis,mt))
{
// return the MESHGROUP_TRANSFORM to the way it was before exit
mt.P.rotparam.angle=save_angle;
mt.P.rotparam.axis=save_axis;
return false; //failed
}
// now rotate around the the two axis value of the intended rotation
mt.P.rotparam.angle=save_angle;
mt.P.rotparam.axis=temp_axis;
bool b=vs->MeshgroupTransform(vis,mt);
// finally rotate back the way we came away from the xz plane
mt.P.rotparam.angle=(float)(tmp_angle);
mt.P.rotparam.axis=z_axis;
b= (vs->MeshgroupTransform(vis,mt) && b);
// return the MESHGROUP_TRANSFORM to the way it was before exit
mt.P.rotparam.angle=save_angle;
mt.P.rotparam.axis=save_axis;
return b; //succesful
}
else
return vs->MeshgroupTransform(vis,mt);
}
 
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