Datasheet

55
CHAPTER 1
CHAPTER 2
CHAPTER 3
CHAPTER 4
CHAPTER 5
CHAPTER 6
CHAPTER 7
CHAPTER 8
CHAPTER 9
CHAPTER 10
CHAPTER 11
CHAPTER 12
CHAPTER 13
CHAPTER 14
APPENDICES
INDEX
■ BUILDING A SPIRAL STAIRCASE
Now let’s make something a
little more impressive—a spiral
staircase (Figure 3.18). This time
we’re going to use a combination of
grid-snapping and rotation.
1. Rez a step with the same
dimensions as the last
step (X = 1.500, Y =
0.400, and Z = 0.050)
and again, set Grid Units
to 0.300.
2. We now want to link a
pivot point into the step.
Drag-copy another step
in the X direction so both
steps sit side by side, then
resize this new prim so
that it’s a perfect square
(set X = 0.400).
Now we want to place the two prims perfectly side by side, so we are going to use the math we
learned earlier.
3. Take half the X size of the fi rst prim (1.5 ÷ 2 = 0.75) and half the X size of the second
prim (0.4 ÷ 2 = 0.200).
4. Add the two together (0.75 + 0.2 = 0.95).
5. Find the X position of the fi rst prim, add 0.95 to it, and then use that as the X position
value for the smaller pivot prim.
You now have two prims set perfectly side by side. You may want to tint the smaller pivot prim
to another color, such as red—you will be deleting the other pivot prims later, but for now we will be
using them as a center point for rotation.
Now you need to link the two prims together. In the previous chapter I mentioned how the order
in which you select prims prior to linking is very important. Well this will be your fi rst real example as
to why. When we link prims, the last prim selected becomes the root prim—the prim around which
the whole build will rotate when we start to enter rotational values.
6. Select the long step fi rst, and then Shift-select the smaller pivot prim. Press Ctrl+L
to link your prims. (The root prim glows yellow when selected, while all other prims
glow blue.)
7. As we did with the regular staircase, we want to start out with our stair snapped to a
spot on the grid. Go to Tools
▶ Snap Object XY to Grid (or use Shift+X), and then use the
planar drag handles to snap the step on the z-axis.
8. Using the planar drag handles, Shift-drag the step upward to produce another step.
9. Do this several more times until you have a stack of steps with 0.300 meters between
every step.
Now we are going to rotate each step by entering incrementally larger numbers into the Z rotation
axis. We can rotate each step at any increment as long as we use the same increment for each step. I
think 10 degrees of rotation per step will look nice.
Figure 3.18: Perfect spiral stairs
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