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Thread: Custom Tools

  1. #1
    Sketchpad Developer
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    Custom Tools

    I just returned from a conference at which I got a couple of interesting questions that led me to create some tools that others may find useful. So I started this thread; feel free to comment on these tools, to request other tools, or to describe useful tools of your own. (There are also a number of very useful tools on the Sketchpad Resource Center: http://www.dynamicgeometry.com/Gener....html#Toolkits)

    Here are the two new tools I created:

    Circle Inversion: Mirek Majewski wanted an easier way to invert points and paths through a given circle, so I created two tools (one to invert a point, and the other to invert a path). To use them, you need to click only on the circle and the object to invert. Here's the tool:
    http://sketchexchange.keypress.com/s...nversion-tools

    Point Lever: Mirek's friend Michael Sejfried, who's done some impressive work exploring and proving theorems about triangles, wanted a way to move a point by a fraction of a pixel. That's hard, because the mouse only moves a pixel at a time. So I created a Point Lever tool: you can click the target point, and then two more points that determine the direction of the lever, and click Initialize to configure the lever. You get a lever point (actually a dilated image) that you can move by 1 pixel to move the target point by 0.1 pixel. You can click Finer to increase the sensitivity by a factor of 10 for each click, to 0.01 pixel, or 0.001 pixel, and so forth. Here's the tool:
    http://sketchexchange.keypress.com/s...int-lever-tool

  2. #2
    Sketchpad Developer
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    Custom Tools for Stacking Cubes

    I had another question come up, about creating a sketch that shows a stack of cubes. So I posted a file that explains how to do it using either copy/paste and merge points, or with a custom tool. The sketch contains the custom tool to make a cube, and three other tools that are useful when you want to show only certain faces of the cubes in order to stack them in a particular arrangement. Here's where I put the sketch:
    http://sketchexchange.keypress.com/s...stacking-cubes

  3. #3
    Sketchpad Developer
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    Angle Slider Tools

    I just posted some angle slider tools (http://sketchexchange.keypress.com/s...e-slider-tools). They include a couple of circular sliders, one going from 0° to 360° and the other from –180° to 180°, an unbounded linear slider for when you want a larger domain than 360°, and an adjustable spiral slider that allows you to drag 'round and 'round and 'round.

  4. #4
    Sketchpad Developer
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    Numeric Tools

    I had a question from a user who wanted to fix a parameter so that its value always stayed within a certain interval. Using the Boolean tools (http://www.dynamicgeometry.com/Gener....html#Toolkits), you can do a calculation that compares the parameter's value to the upper and lower limits, and based on the results returns the lower limit (if the parameter's value is less), the actual value of the parameter, or the upper limit (if the parameter's value is greater). But the user's question seemed like a sufficiently useful operation that I decided to make a custom tool out of it, and add it to a toolkit of mine that already includes div/mod, min/max, and even/odd tools. (I also decided to fill the toolkit out with floor/ceiling tools. Floor(x) returns the largest integer that is ≤ x, and ceiling(x) returns the smallest integer ≥ x.) You can get these tools here: http://sketchexchange.keypress.com/s.../numeric-tools

  5. #5

    Angle Slider and Measurements for Angles > 360°

    I had a question about my angle slider tools. Gerald wanted to know if it was possible to make the spiral slider truly sensitive to the actual number of rotations. (In the original slider, you could jump from one arm of the spiral to another, increasing the angle by 360° without actually rotating about the center.) This new sketch contains three tools:
    1. A tool that measures an angle and is sensitive to the number of turns that the terminal side of the angle has made about the center point.
    2. A similar tool that shows a spiral to indicate the number of turns visually. For instance, when the measurement is 900°, the spiral shows two and a half turns from the initial side of the angle.
    3. A slider on a circle that tracks the number of rotations from the starting point and shows a spiral corresponding to the current slider value.
    For more details, there's an extensive technical background note on the last page of the sketch.
    All three tools require an active Movement button to work. (This button allows hidden objects in the sketch to keep track of the number of rotations.)
    Last edited by Scott; 02-05-2013 at 07:25 PM.

  6. #6

    Architectural Distance Measurements

    Architectural and technical drawings often display measurements using a broken two-headed arrow, with the measurement in the middle of the break. A user asked how to do this in Sketchpad, so I created two tools that I've posted here in Sketch Exchange..
    One tool shows the distance directly between the two given points, and the other allows you to offset the broken arrow from the measured points. Both allow you to set the scale on which to base the measurements.
    Attached Images

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