Jerry Davis mailto:jdawgaz@gmail.com
November 20, 2015 at 07:19
I have been teaching openscad to a mix of people (my amateur radio
buddies), and some have had a little experience in programming (like
basic), others have had fairly extensive programming experience, and
others have absolutely none.

I started talking about rotation, and got them thoroughly confused. It
is not an easy concept, even when you are a programmer.

So, I came up with the following script which I hope will help
alleviate the visualization of what rotate does.

Just wanted to share this.

Jerry

============== script ==============

$fn = 300;

module textcube(t, c) {
// t = text, c = color
color(c) cube(2, center=true);
translate([-0.5,-0.5,0.75]) text(t, size=1);
}

// make a part, that has n,s,e,w, up, down obvious orientations.
module part() {
cylinder(h=5,r=3, center=true);
translate([3,0,0]) rotate([90,0,0]) rotate([0,90,0]) textcube("N",
"Blue");
translate([0,0,3]) rotate([0,0,0]) rotate([0,0,0]) textcube("U",
"Magenta");
translate([-3,0,0]) rotate([-90,0,0]) rotate([0,-90,0])
textcube("S", "MediumSpringGreen");
translate([0,-3,0]) rotate([0,0,0]) rotate([90,0,0]) textcube("E",
"PeachPuff");
translate([0,3,0]) rotate([0,180,0]) rotate([-90,0,0]) textcube("W",
"Olive");
translate([0,0,-3]) rotate([180,0,0]) rotate([0,0,0]) textcube("D",
"LightSteelBlue");
}

// alternately change the values for the rotate transformation
// to see what happens to our part. I suggest values of 90, and -90
// for the various values.
// for instance, see what rotate([0,0,0]) does (which doesn't rotate
at all, obviously)
// then change it to 90 in the x direction (rotate([90,0,0]).
// what happens to our part then?
// change it back to 0, then back to 90 several times until you can
visualize what is happening
// then try 90 in the y direction, etc.
// later try doing in the 90 degrees in both the x and y directions?
// what happens?

rotate([0,0,0]) part();

=========== end of script ============

--
Extra Ham Operator: K7AZJ
Registered Linux User: 275424
Raspberry Pi and Arduino developer

/The most exciting phrase to hear in science - the one that heralds
new discoveries - is not "Eureka!" but "That's funny...".
/- Isaac. Asimov

/I//f you give someone a program, you will frustrate them for a day;
if you teach them how to program, you will frustrate them for a lifetime.
/- Anonymous

/If writing good code requires very little comments, then writing
really excellent code requires no comments at all!
/- Ken Thompson

OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

Jerry,

I think this is really useful for beginners, but one thing concerns me,
which is the use of cardinal directions to represent the axes which already
have names. Additionally, the axes already have colors in OpenSCAD as well
(X=Red, Y=Green, Z=Blue). By changing both the names and colors of the
axes, I think it actually may make it more confusing when trying to
relate what's going on with the very-helpful axes visualizer in the preview
pane, as well as with the rotation vector. Which number rotates around the
NS axis, for instance?

Here is a version which names the directions using +X, -X, etc, and uses
the already-defined colors, with a brighter color for positive and darker
color for negative. I think this has a similar useful effect, but uses
visual "terms" already established in OpenScad (and many other 3d programs).

As an aside, the text() module takes the very handle halign and valign
parameters, which are an easier way of centering text than using manual
offsets.

============== script ==============

$fn = 300;

module textcube(t, c) {
// t = text, c = color
color(c) cube(2, center=true);
translate([0,-0,0.75]) text(t, size=1, halign="center", valign="center");
}

// make a part, that has n,s,e,w, up, down obvious orientations.
module part() {
cylinder(h=5,r=3, center=true);

translate([3,0,0]) rotate([90,0,0]) rotate([0,90,0]) textcube("+X",
[1,0,0]);
translate([-3,0,0]) rotate([-90,0,0]) rotate([0,-90,0]) textcube("-X",
[.5,0,0]);

translate([0,3,0]) rotate([0,180,0]) rotate([-90,0,0]) textcube("+Y",
[0,1,0]);
translate([0,-3,0]) rotate([0,0,0]) rotate([90,0,0]) textcube("-Y",
[0,.5,0]);

translate([0,0,3]) rotate([0,0,0]) rotate([0,0,0]) textcube("+Z",
[0,0,1]);
translate([0,0,-3]) rotate([180,0,0]) rotate([0,0,0]) textcube("-Z",
[0,0,.5]);
}

// alternately change the values for the rotate transformation
// to see what happens to our part. I suggest values of 90, and -90
// for the various values.
// for instance, see what rotate([0,0,0]) does (which doesn't rotate at
all, obviously)
// then change it to 90 in the x direction (rotate([90,0,0]).
// what happens to our part then?
// change it back to 0, then back to 90 several times until you can
visualize what is happening
// then try 90 in the y direction, etc.
// later try doing in the 90 degrees in both the x and y directions?
// what happens?

rotate([0,0,0]) part();

=========== end of script ============

Best,

~ Yona

Jerry Davis jdawgaz@gmail.com
November 20, 2015 at 07:19
I have been teaching openscad to a mix of people (my amateur radio
buddies), and some have had a little experience in programming (like
basic), others have had fairly extensive programming experience, and others
have absolutely none.

I started talking about rotation, and got them thoroughly confused. It is
not an easy concept, even when you are a programmer.

So, I came up with the following script which I hope will help alleviate
the visualization of what rotate does.

Just wanted to share this.

Jerry

============== script ==============

$fn = 300;

module textcube(t, c) {
// t = text, c = color
color(c) cube(2, center=true);
translate([-0.5,-0.5,0.75]) text(t, size=1);
}

// make a part, that has n,s,e,w, up, down obvious orientations.
module part() {
cylinder(h=5,r=3, center=true);
translate([3,0,0]) rotate([90,0,0]) rotate([0,90,0]) textcube("N",
"Blue");
translate([0,0,3]) rotate([0,0,0]) rotate([0,0,0]) textcube("U",
"Magenta");
translate([-3,0,0]) rotate([-90,0,0]) rotate([0,-90,0]) textcube("S",
"MediumSpringGreen");
translate([0,-3,0]) rotate([0,0,0]) rotate([90,0,0]) textcube("E",
"PeachPuff");
translate([0,3,0]) rotate([0,180,0]) rotate([-90,0,0]) textcube("W",
"Olive");
translate([0,0,-3]) rotate([180,0,0]) rotate([0,0,0]) textcube("D",
"LightSteelBlue");
}

// alternately change the values for the rotate transformation
// to see what happens to our part. I suggest values of 90, and -90
// for the various values.
// for instance, see what rotate([0,0,0]) does (which doesn't rotate at
all, obviously)
// then change it to 90 in the x direction (rotate([90,0,0]).
// what happens to our part then?
// change it back to 0, then back to 90 several times until you can
visualize what is happening
// then try 90 in the y direction, etc.
// later try doing in the 90 degrees in both the x and y directions?
// what happens?

rotate([0,0,0]) part();

=========== end of script ============

--
Extra Ham Operator: K7AZJ
Registered Linux User: 275424
Raspberry Pi and Arduino developer

The most exciting phrase to hear in science - the one that heralds new
discoveries - is not "Eureka!" but "That's funny...".- Isaac. Asimov

I
*f you give someone a program, you will frustrate them for a day; if you
teach them how to program, you will frustrate them for a lifetime. *-
Anonymous

If writing good code requires very little comments, then writing really
excellent code requires no comments at all!- Ken Thompson

OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org