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24
Chapter 2: Creating Geometries
Figure 2-3 Indexed Attributes
When to Index Attributes
For all primitives in a csGeoSet, you have to decide whether to use indexed or sequential
attributes; that is, all of the primitives within one csGeoSet must be referenced either
sequentially or by index. You cannot mix the two reference methods.
The governing principle for indexing attributes or not is how many vertices in a
geometry are shared. Consider the following two examples in Figure 2-4, where each dot
marks a vertex.
StripLengths
PrimCoords
ColorBind
MormalBind
TexCoordBind
CoordSet
ColorSet
NormalSet
TexCoordSet
CoordIndexSet
ColorIndexSet
NormalIndexSet
TextCoordIndexSet
< x, y, z >
.
.
.
< r, g, b >
.
.
.
< nx, ny, nz >
.
.
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< x, y, z >
.
.
.
le1
le2
le3
.
.
.
i1
i2
i3
.
.
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i1
i2
i3
.
.
.
i1
i2
i3
.
.
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i1
i2
i3
.
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csGeoSet