Modify Slider Joint 2d via script?

Questions & Answers
1

Been trying to modify the translation limits of these new Slider Joint 2D’s. I add them onto gameobjects at runtime, so I need to do it via script. These are two things I’ve tried, but don’t seem to work. Any help is appreciated!

sliderJoint.limits.max = targetLength;

error CS1612: Cannot modify a value type return value of `UnityEngine.SliderJoint2D.limits’. Consider storing the value in a temporary variable

sliderJoint.limits = new JointTranslationLimits2D(0,targetLength);

The type UnityEngine.JointTranslationLimits2D' does not contain a constructor that takes 2’ arguments

2

I’m not familiar with Slider Joints, but for this type of situation you have a few options.

  1. Copy the existing thing you want to change (here it’s sliderJoint.limits) into a new variable, change the part(s) you want, then assign it back.
  2. Create a new thing of the type you want, set its values, then assign it to the object you want to change.

Here’s how option 1 might look:

     // 1) Copy it.
    JointTranslationLimits2D copiedLimits = sliderJoint.limits;
    // 2) Change what you need in the copy.
    copiedLimits.max = targetLength;
    // 3) Assign it back
    sliderJoint.limits = copiedLimits;

Option 2 would be something like this:

    // 1) Make a new one.
    JointTranslationLimits2D newLimits = new JointTranslationLimits2D();
    // 2) Fill out all the fields.
	newLimits.max = targetLength;
	newLimits.min = 0.0f;
    // 3) Assign it.
    sliderJoint.limits = newLimits;

I personally like option 1 in most cases, since I only have to change what I need.