OpenSCAD: Homework Spring Semester 2016/2017

Keyboard Body

The keyboard body is a prism with a rectangular or square base with four rounded corners. The size of the body depends on the basemargin and basez parameters, and on the size of the key area (more information in the next section).

Several images:

Top view:

Side view:

The drawn axes are very important for placing the object in the Cartesian system. In the first image, note that the keyboard goes in the direction of the positive X axis and the negative Y axis (this looks weird, but makes sense given the representation of the keyboard layout). The keyboard lies directly on the XY plane, all Z coordinates are non-negative.

Keys and Key Holes

The key section contains keys and holes for them.

One key is a prism with a rectangular or square base and a rounded top surface, sometimes containing text. This is what a simple 1x1 key and its hole look like:

From above (dashed line marks the edge of the hole):

From the side (view along the Y axis):

Note the keydip parameter. It is the same for keys of any size, so the radius of the cutout must adapt to this value. The curvature happens only along the Y axis - so it’s not a spherical cutout, but a cylindrical one.

keysize is a parameter affecting the size of all keys. Individual keys, however, can occupy space of multiple grid cells, so each key also has its own size information. The key in the images above has size [1,1].

Holes are separated by a wall of thickness defaultspace (if defaultspace is not zero). Here’s what multiple keys will look like (the image can be enlarged by clicking the link):

Here you can see how to determine the size of keys larger than [1,1]: They occupy the same space that several keys next to each other would occupy (including the space between them). The key in the bottom row has size [2,1]:

This is what keys look like from the side (in cross-section along the Y axis). In the first image there are three keys of size [1,1], in the second one key of size [1,1] and one of size [2,1]:

Note that the wall of thickness defaultspace is only between keys. The wall thickness next to the outermost keys is basemargin. Also note that the keys are floating in the air; this is of course quite problematic for 3D printing, but in the homework it’s like this anyway and you don’t need to worry about it.

Text on Keys

Some keys may contain text on them. From the XY perspective, the text on the key is centered:

Even if it’s a larger key (e.g., [2,1] or maybe [5,10]), the text is still in its center.

The parameters for the entire module textsize and textz affect the size of the text.

textsize should be passed to the text() primitive as the size argument. textz determines the depth of the letter (along the Z axis, as the name suggests).

Note that the text also contains a cylindrical cutout, just like the key itself. Don’t try to "bend" the text, just extrude it upward and cut out the appropriate cylinder from it. The radius of the cylindrical cutout of the key and the text on it is the same.

How is text done in OpenSCAD? Here you can see an example call to the text() primitive, which creates a 2D object centered on the XY plane:

text("A", halign="center", valign="center", size=textsize);

Do not change the default font. You can assume that the text we give you will always fit on the key.

For better visualization of a key with text, we attach previews of a 3D model of a key with the letter A:

Pro-tip: When extruding a 2D text and subtracting some other object from it, add the parameter convexity=10 to the linear_extrude() call - your previews (F5) will look better. (This has no effect on tests, but it will be more pleasant to work with.)

Keyboard Layout

The keyboard layout is given by the layout parameter. It’s a vector of vectors of vectors (oh!). We’ll break it down from the inside. One key (or empty position) is represented by a vector of 0, 2 or 3 values. An empty vector represents a place without a key. The first two values of the vector determine the size and the third optional value is the text. (To find the length of a vector use len(vector).) Several examples:

[1,1] // standard sized key without label
[8,1] // very long key without label (like spacebar)
[3,1,"Enter"] // long variant of Enter key
[1,2,"+"] // tall key with + symbol, like on numpad
[10,10,"I love OpenSACD"] // insanely large key with long text - still a valid key

Keys form rows. Multiple rows form the keyboard layout. All rows have the same length.

To make it a bit easier for you, there are placeholders in the layout where a key from another grid cell occupies space. When there’s a key [2,1] in the layout, it’s immediately followed by one [] placeholder. When there’s a key [3,1] in the layout, it’s immediately followed by two [] placeholders. When there’s a tall key in the layout, like [1,2], there are [] placeholders at its position in the following rows (here one). Only valid layouts will be tested.

Let’s show some examples. For starters, something simple:

[
[[1, 1, "X"], [1, 1, "O"]],
[[2, 1, "BI-3DT"], []],
[[1, 1, "<"], [1, 1, ">"]],
]

Layout with keys spanning multiple rows:

[
[[1,2], [1,1]],
[[], [1,2]],
[[1, 1], []],
[[2,2], []],
[[], []],
]

And something more interesting:

[
[[1,1, "Esc"], [], [1,1,"F1"], [1,1,"F2"], [1,1,"F3"], [1,1,"F4"], [], [1,1,"F5"], [1,1,"F6"], [1,1,"F7"], [1,1,"F8"], [], [1,1,"F9"], [1,1,"F10"], [1,1,"F11"], [1,1,"F12"], [], [1,1], [1,1], [1,1], [], [], [], [], []],
[[], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], []],
[[1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [1,1], [2,1], [], [], [1,1], [1,1], [1,1], [], [1,1], [1,1], [1,1], [1,1]],
[[2,1], [], [1,1,"Q"], [1,1,"W"], [1,1,"E"], [1,1,"R"], [1,1,"T"], [1,1,"Y"], [1,1,"U"], [1,1,"I"], [1,1,"O"], [1,1,"P"], [1,1], [1,1], [2,2], [], [], [1,1], [1,1], [1,1], [], [1,1], [1,1], [1,1], [1,2]],
[[2,1], [], [1,1,"A"], [1,1,"S"], [1,1,"D"], [1,1,"F"], [1,1,"G"], [1,1,"H"], [1,1,"J"], [1,1,"K"], [1,1,"L"], [1,1], [1,1], [1,1], [], [], [], [], [], [], [], [1,1], [1,1], [1,1], []],
[[3,1], [], [], [1,1,"Z"], [1,1,"X"], [1,1,"C"], [1,1,"V"], [1,1,"B"], [1,1,"N"], [1,1,"M"], [1,1], [1,1], [1,1], [3,1], [], [], [], [], [1,1], [], [], [1,1], [1,1], [1,1], [1,2]],
[[2,1], [], [2,1], [], [6,1], [], [], [], [], [], [2,1], [], [2,1], [], [2,1], [], [], [1,1], [1,1], [1,1], [], [2,1], [], [1,1], []],
]