Question with wrapping muscles tutorial

Main Forum
1

I previously completed the wrapping muscles tutorial and went back to this model to learn more about wrapping muscles.

I tried to replace the cylindrical surface with a sphere using the following code:

  AnyRefNode CylCenter = {
    sRel = {0, 0, 0};
    //ARel = RotMat(20*pi/180,y);
    
    AnySurfEllipsoid WrapSurf = {
      Radius = {0.15, 0.15, 0.15};
      //Length = 0.4;
      AnyDrawParamSurf drv = {};
      //CapRatio = 0.100000;
    };
    
  };

This code seemed to work BUT muscle 2 for which InitWrapPosVectors were set to make the muscle wrap under the object wrapped over the object.

I modified to origin and insertion points for this muscle so that they were on the xy plane (i.e. set z to zero) to see if this was the problem. When I did this I got the following error:

ERROR(OBJ.LIB.OOS1) : E:/AnyBody_Monique/Demos/MuscleDemo.4.any : Muscle2.SPLine : Unexpected exception in the library OOSol :
OOSol exception : MISSING MESSAGE.

This error is the same as I was experiencing with my own model. Maybe there is lack of understanding on my part on how the ellipsoid surfaces work. Could you please help me with this problem.

Thanks

Monique

2

Hi Monique,

This is not your fault but a weakness in the system’s wrapping algorithm. The incomprehensible error message means that something went wrong in the wrapping algorithm. A typical cause of this error is when a wrapping muscle falls off the end of a wrapping object. It may happen easily with spheres because they are round in all directions and therefore offer no resistance against muscles sliding off them.

The error also sometime occur when the muscle string has too few points compared with the width of the object it wraps about, such that the object falls between two points on the muscle.

Best regards,
John