Example: My Gosh, It’s Full of Stars!
Open in turtleSpaces IDERun starscape to create a galaxy of randomly-shaped and colored stars.
TO star :radius :points :size :filled
;takes number number number boolean (true or false)
;eg star 10 9 40 false
;or star 20 5 50 true
pu dropanchor tether
;pull up the turtle pen, drop the 'anchor' to set the 'anchor point' to the current position, and do not change it if the turtle's rotation changes (tether)
;the anchor point is the point the orbit primitives orbit around
if :filled [polyspot :radius :points * 2
if oddp :points [rt 360 / :points / 4]]
;if creating a filled star, create a polygon to fill in the center
;if the star has an odd number of points, we need to turn a little
pullout :radius
;pull out from the anchor point, which is currently the turtle's position
repeat :points [
;repeat once for each point:
pu make "position position
;set the :position container to the current turtle position
orbitleft 360 / :points / 2
;orbit around the anchor point (in this case the center) to the left
;a fraction of 360 degrees divided by the number of points divided by 2
pullout :size
;pull the turtle out from the center of the star (anchor point)
setvectors direction :position
;point the turtle toward the previous position
if not :filled [pd line distance position :position]
;if not making a filled star, create a line in front of the turtle of
;the length required for its end to be the previous turtle position.
if :filled [frag]
;if creating a filled star, create a 'fragment' based on the last three
;turtle positions
pu make "position position
;set the :position container to the current position
pullin :size
;pull the turtle in toward the center of the star (anchor point)
orbitleft 360 / :points / 2
;orbit to the left again a similar amound to the last orbitleft
setvectors direction :position
;point toward the previous position
if not :filled [pd line distance position :position]
;create a line if not a filled star similarly to the previous line
if :filled [frag]
;create a fragment if a filled star similarly to the previous frag
]
END
TO starscape
reset ht snappy:setposition [0 0 0] snappy:dropanchor repeat 200 [pu home randvec fd 1000 + random 1000 up 90 snappy:setvectors direction myrtle:position randfc randpc randps randfs star 10 + random 100 3 + random 20 10 + random 90 randbool]
END
