10.5 A Bouquet of Arrows
Let's draw a ``bouquet'' of arrows. Each arrow is identical. The arrowheads are uniformly placed on a circle parallel to the -plane. Thus the position of each arrow differs only by the angle , , between the arrow and the -axis on the -plane.
Our bouquet is rather special: each arrow has a different color (which won't be evident here, unfortunately). This is arranged by letting the color of each successive arrow be denoted by . In this way, the color of arrows ranges from red to green to violet. Here is a program to draw a bouquet of arrows.
drawBouquet(n,title) ==}{}
angle := 0.0@DFLOAT The initial angle
sp := createThreeSpace() Create empty space $sp$
for i in 0..n-1 repeat For each index i, create:
start := point [0.0@DFLOAT,0.0@DFLOAT,0.0@DFLOAT,angle]
the point at base of arrow;
end := point [cos angle, sin angle, 1.0@DFLOAT, angle]
the point at tip of arrow;
arrow := makeArrow(start,end) the $i$th arrow
for a in makeArrow(start,end) repeat For each arrow component,
curve(sp,a) add the component to $sp$
angle := angle + 2*%pi/n The next angle
makeViewport3D(sp,title) Create the viewport from $sp$
Read the input file.
)read bouquet
A bouquet of a dozen arrows.
drawBouquet(12,"A Dozen Arrows")
