Make dragged point leave trace

Questions
1

Hi everyone,

I have been interested in getting a dragged point to leave a trace of where it has been on the graph, but I haven’t figured out how to code it. In other words, as you drag a point around the graph, it leaves a continuous trace, or discrete points if there are step values associated with the coordinates.

Below is a workaround I came up with for investigating a linear inequality. I capture each sketch point, color it in white, then add that point to a set of plotted values.

I’d rather just let a graph point itself add to a set of plotted values.

Is there a straightforward tool I’m missing?

Thanks,
Jason

2

I’m wondering if anyone has figured out another approach? In particular, I would like some sort of command that just turns on a trace-- GSP and GeoGebra both have one. The situation I am working on at the moment is a geometric construction of a parabola and I want the point (C) to leave a path of where it has been when point B is moved.

3

I don’t think there is a simple command. But I used actions and tickers to make this. Does this approach do what you need?

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4

I also did something similar here to trace the users’ graph.

5

Thanks Daniel. Going to have to play with this a bit.

6

Here is a way it could look. You basically just keep adding the current point to the list with the ticker running the action continuously, but first check to see that the point is not already in the list so it doesn’t just grow without bound. Parabola Noodle 2

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7

This is awesome. TY Daniel.

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8

I’ve done something similar to your “stamp” a line segment activity in the regular Desmos graphing calculator, but now I’m exploring the Desmos Geometry calculator which has more commands with line segments and polygons that I’d like to take advantage of. So I’m trying to recreate the stamping in the Desmos Geometry with segments, but I’m getting an “Cannot compare a segment to a segment” message. Do you have any suggestions on making this type of dragged object trace with objects other than points? Here is what I have so far: https://www.desmos.com/geometry/xt4ygrdyco

9

I haven’t played with the Geometry calculator much yet, so there may be a better way to deal with segment comparisons. But instead I just made two separate lists for the endpoints and checked that either of the current points moved before adding the new endpoints to the lists. Does this do what you are looking for? geometry test | Desmos

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10

You do the coolest stuff, Daniel!

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