Graphics Programs Reference
In-Depth Information
6.
Press ↵ to finish the patch surface.
7.
To get a better view of the surface, select the Shaded With Edges option from the Visual
Styles menu in the Viewport Controls.
You may have noticed that the grip arrowhead options in step 5 were similar to the grip
options you saw for the Surface Blend tool. The Surface Patch tool offers an additional command
option called CONStrain geometry. Table 23.1 describes these options.
TABLE 23.1:
The Surface Blend and Surface Patch options
OPTION
FUNCTION
(G0) Position
Causes the surface to connect without any blending curvature.
(G 1) Tan gent
Causes the surface to blend with direction.
(G2) Curvature
Causes the surface to blend with direction and similar curvature or rate of
change in surface direction.
CONtinuity
Controls how smoothly the surfaces flow into each other.
Bulge magnitude
Allows you to adjust the amount of bulge or curvature in the blend surface.
Values can be between 0 and 1.
CONStrain geometry
(Surfpatch command)
Offers additional guide curves to control the patch surface.
Understanding Associativity
Surface Associativity is a feature that is on by default, and its function is similar to the
Associative feature of hatches (see Chapter 7, “Mastering Viewing Tools, Hatches, and External
References,” for more on hatches). You may recall that when you create a 2D hatch pattern with
the hatch Associative feature turned on, the hatch's shape will conform to any changes made to
the boundary used to enclose the hatch pattern.
Surface Associativity in surface modeling works in a similar way, only instead of a hatch pat-
tern conforming to changes in a boundary, the surface conforms to changes in the shapes that
are used to create them. For example, if you were to make changes to the arc that you used to
extrude the arc surface, the arc surface and the trimmed cylinder would also follow the changes.
U
S I N G
A
S S O C I A T I V I T Y
T O
E
D I T
A
S
U R F A C E
M
O D E L
Rather than try to explain any further, let's try it out so you can see firsthand how associativity
works:
1.
Return to the Surfaces1.dwg file and click the arc to expose its grips.
2.
Click the square grip at the arc's left endpoint and drag it downward along the Z axis.
When it is roughly in the position shown in Figure 23.46, click again to fix the grip's loca-
tion. The shape of the surface model changes to conform to the new shape of the arc.
