Rotation of Child Prims

[xtc4u]

Trying to write a general rotator of child prim routine.  The code below works but only rotates on a single axis whether I pass in x, y or z.  I'm sure it's a matter of basic misunderstanding of rotation but I am stumped.  

Whether I call MoveChildsRot as below I get the same rotation on the Y axis:

MoveChildsRot(10, "x", 2);
llSleep(2);
MoveChildsRot(10, "y", 2);
llSleep(2);
MoveChildsRot(10, "z", 2);

 

 

// calc the rotation
rotation rotAmount ( float amt, string xyz)
{
    vector x_angles = < amt,0,0 >;
    vector y_angles = < 0,amt,0 >;
    vector z_angles = < 0,0,amt >;
    vector angles_in_radians;
        
    if (xyz = "x")
    {
        angles_in_radians = x_angles* DEG_TO_RAD; // Change to Radians
    }
    if (xyz = "y")
    {
        angles_in_radians = y_angles* DEG_TO_RAD; // Change to Radians
    }
    if (xyz = "z")
    {
        angles_in_radians = z_angles* DEG_TO_RAD; // Change to Radians
    }
    if (debug) llOwnerSay("Angle in Radians: " + (string)angles_in_radians);    
    return llEuler2Rot ( angles_in_radians ); // Change to a Rotation
}

// Rotate a child prim 
//  nAmount: number of degrees to rotate (i.e 10, -10)
//  str_xyz: axis to rotate (i.e. "x", "y", "z")
//  nun: child prim number
MoveChildsRot(integer nAmount, string str_xyz, integer num)
{
    // rotate a child prim    
    list        lRot = llGetLinkPrimitiveParams(num, [PRIM_ROT_LOCAL]);
    rotation    localRot = llList2Rot(lRot, 0); // current Rot
    rotation  deltaRot;

    if (debug) llOwnerSay( (string)nAmount);    
    if (debug) llOwnerSay("xyz: " + str_xyz + " " +  (string)localRot);
    
    deltaRot = rotAmount ((float)nAmount,str_xyz) ;
    
    llSleep(.5);
    
    if (debug) llOwnerSay("xyz2: " + str_xyz + " Delta: " + (string)deltaRot);
    
    llSetLinkPrimitiveParamsFast(num , [ PRIM_ROT_LOCAL, (localRot * deltaRot)] ) ;
        
}

 

[Rolig Loon]

Two mistakes, one fatal:

(1) You are using "=" (assignment) in the if statements in the rotAmount function, instead of "==" (equivalence), and

(2) Your second and third if tests should be else if tests.

rotation rotAmount ( float amt, string xyz){    vector x_angles = < amt,0,0 >;    vector y_angles = < 0,amt,0 >;    vector z_angles = < 0,0,amt >;    vector angles_in_radians;            if (xyz == "x")    {        angles_in_radians = x_angles* DEG_TO_RAD; // Change to Radians    }   else if (xyz == "y")    {        angles_in_radians = y_angles* DEG_TO_RAD; // Change to Radians    }    else if (xyz == "z")    {        angles_in_radians = z_angles* DEG_TO_RAD; // Change to Radians    }    if (debug) llOwnerSay("Angle in Radians: " + (string)angles_in_radians);        return llEuler2Rot ( angles_in_radians ); // Change to a Rotation}

[xtc4u]

Wow, talk about a big time rookie mistake.  I have stared at this code for you can't imagine how long, I really should have spotted that.  Thanks much.

As to the if vs. if else.  I agree I should have used the if else's but wouldn't it have worked even with just the if's.  I'm assuming it would have but would be less efficient code.  I guess that is what you meant by one fatal and one "not fatal".

Again thank you.

[Rolig Loon]

Yeah.  That one's not fatal, but there's no point in continuing with extra if tests once you have found the one that works, so else if is the better choice. 

[Ela Talaj]

An interesting thing here is that if left as is it should always rotate around all 3 coordinates because xyz = <whateverstring> evaluates to TRUE so condition if(xyz=<whateverstring>)  (with "=" instead of "==") is always satisfied.

 

[Nexii Malthus]

Not quite correct.

 

It would always use the Z coordinate because the last assignment would win every time.

[xtc4u]

OK here is the final version, tightened up a bit and only one function.  Thanks for the help and second set of eyes. Note it does not check if the prim number is valid.

 

// Rotate a child prim //   degrees: number of degrees to rotate (i.e 10, -10)//       xyz: axis to rotate (i.e. "x", "y", "z")//  prim_nun: child prim numberMoveChildsRot(float degrees, string xyz, integer prim_num){      list lRot = llGetLinkPrimitiveParams(prim_num, [PRIM_ROT_LOCAL]);    vector angles_in_radians;            if (xyz == "x") {        angles_in_radians = < degrees,0,0 > * DEG_TO_RAD;     } else if (xyz == "y") {        angles_in_radians = < 0,degrees,0 > * DEG_TO_RAD;     } else if (xyz == "z") {        angles_in_radians = < 0,0,degrees > * DEG_TO_RAD; }    // rotate the child prim      llSetLinkPrimitiveParamsFast(prim_num ,         [ PRIM_ROT_LOCAL,(llList2Rot(lRot, 0) * llEuler2Rot ( angles_in_radians ))] ) ;       }

 

[Ela Talaj]

Correct. Didn't notice that each conditional writes the same variable so the last value remains. Late at nite when seeing several if's in a row and no else's, one might assume they would write into different variables