pointOnPath wraps at 100% to 0%

[fjenett]

Currently (NodeBox 3.0.45) the point-on-path wraps at 100% to 0% which is not desirable because one might want to step up to the full 100% (think animation never reaching the final destination).

I think the problem is the modulo here: https://github.com/nodebox/nodebox/blob/c15874a11f7b90c262afcd2db5f20ea69dc011b2/src/main/java/nodebox/function/CoreVectorFunctions.java#L460

Checking > 100 and then setting to exactly 100 (same for 0) would be a better strategy:

    public static Point pointOnPath(AbstractGeometry shape, double t) {
        if (shape == null) return null;
        if ( t < 0 ) t = 0;
        else if ( t > 100 ) t = 100;
        return shape.pointAt(t / 100);
    }

[fdb]

Thanks! This is indeed not the desired behaviour.

There are two "correct" solutions:

• as-is: this is useful in some cases where going over the point actually gives an interesting result (think "extrapolation", ie. http://www.enigmeta.com/codevember/18/).
• Clamping: so values stay on the path.

I'm not sure which is the right one. I'm leaning toward the first one, and then using an extra node to clamp the value.

[fjenett]

Extrapolation is fine with me and yes it is interesting. My problem is that it never reaches 100%, so it is not possible to animate between two states because the final state is never reached.

[jcartan]

This is a frequent problem for me too. My workaround is wrap a subnetwork around pointOnPath with a switch inside. If T<100 the switch returns an intermediate state based on pointOnPath; if T=100 it returns the end state instead.