Cylinder

turtleSpaces new terrain functionality provides some great opportunities for simple coding examples with few lines of Logo code, in this case less than 30.

First, we need to introduce the setterrain primitive. setterrain creates ‘terrain’ or a contiguous object of varying elevation.

The above is an example of the object created by setterrain. The setterrain primitive takes a number of parameters, and is a good opportunity to explain the different types of parameters used in turtleSpaces to students.

Build this cool island scene using turtleSpaces Logo and a few basic shapes!

First we begin with a tree. We can build a trunk using a repeat loop of cylinders that get narrower in diameter and longer as we go. We can introduce a slight curve as well by tilting the turtle up a bit each cylinder we create:

Next we need to create the leaves, which we can do using the fiso (filled triangle) primitive. We can use a repeat loop to create a series of triangles growing in size, and then a second repeat loop to create a further series of triangles shrinking in size. In both cases, we tilt the turtle down a bit each triangle we create:

This commented Logo source code creates a thumbtack, a cork board, and then draws random string art using them.

Read the**;comments** to learn more about what the primitives do and what their shortcuts are.

Try some of the primitives out in turtleSpaces interactive mode (the myrtle prompt) and see what they do!

You can drag-select the source code and then paste it into the turtleSpaces editor (which you enter by typing ed and Enter or pressing control-shift-E) using control-shift-V (paste)

Filled triangles

TO tree
  clearscreen penup
  setpos [0 80] setfillcolor 4
  repeat 6 [
    setfillshade -6 + 3 * repcount
    ;repcount returns the current iteration
    back 4 * repcount
    fiso 8 * repcount 5 * repcount
    ;fiso = filled iso triangle
    lower 0.1
  ]
  setfillcolor 8 setfillshade 5
  back 50 slideleft 10
  quad 20 50
  ;trunk
END

‘Tents’ – fiso prisms

TO tree3d
  cs pu setpos [0 80]
  ;cs = clearscreen
  ;pu = penup
  setfc 4
  ;setfc = setfillcolor
  repeat 6 [
    setfs -6 + 3 * repcount
    ;setfs = setfillshade
    bk 4 * repcount
    ;bk = back
    tent 8 * repcount 5 * repcount 10
    lo 0.1
    ;lo = lower
  ]
  setfc 8 setfs 5
  bk 50 sl 10
  ;sl = slideleft
  voxeloid 20 50 10
  ;voxeloids are stretched cubes
END

Cones

TO conetree
  cs pu setpos [0 80]
  setfc 4 up 90
  repeat 6 [
    setfs -6 + 3 * repcount
    ra 4 * repcount
    cone 8 * repcount 5 * repcount 20
  ]
  setfc 8 setfs 5 ra 50
  cylinder 8 50 20
END

Pyramids (5-sided ‘cones’)

TO pyramidtree
  cs pu setpos [0 80]
  setfc 4 up 90
  repeat 6 [
    setfs -6 + 3 * repcount ra 4 * repcount
    cone 8 * repcount 5 * repcount 4
    ;while there is also a pyramid primitive, you can
    ;also create a pyramid by creating a 4-sided cone
  ]
  setfc 8 setfs 5 ra 50
  cylinder 8 50 4
END

4-sided cones

TO tetratree
  cs pu setpos [0 80] setfc 4 up 90
  repeat 6 [setfs -6 + 3 * repcount
    ra 4 * repcount
    cone 8 * repcount 5 * repcount 3]
  setfc 8 setfs 5 ra 50
  cylinder 8 50 3
END