Procedural modelling in Houdini based on Function Representation
Procedural modelling in Houdini based on Function Representation
Procedural modelling in Houdini based on Function Representation
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4.4 <str<strong>on</strong>g>Procedural</str<strong>on</strong>g> functi<strong>on</strong>-<str<strong>on</strong>g>based</str<strong>on</strong>g> <str<strong>on</strong>g>modell<str<strong>on</strong>g>in</str<strong>on</strong>g>g</str<strong>on</strong>g> <str<strong>on</strong>g>in</str<strong>on</strong>g> Houd<str<strong>on</strong>g>in</str<strong>on</strong>g>i<br />
Figure 4.4: The <str<strong>on</strong>g>in</str<strong>on</strong>g>teracti<strong>on</strong> with the FRep API (Kravtsov 2011)<br />
4.4 <str<strong>on</strong>g>Procedural</str<strong>on</strong>g> functi<strong>on</strong>-<str<strong>on</strong>g>based</str<strong>on</strong>g> <str<strong>on</strong>g>modell<str<strong>on</strong>g>in</str<strong>on</strong>g>g</str<strong>on</strong>g> <str<strong>on</strong>g>in</str<strong>on</strong>g> Houd<str<strong>on</strong>g>in</str<strong>on</strong>g>i<br />
4.4.1 The <str<strong>on</strong>g>modell<str<strong>on</strong>g>in</str<strong>on</strong>g>g</str<strong>on</strong>g> workflow<br />
Modell<str<strong>on</strong>g>in</str<strong>on</strong>g>g us<str<strong>on</strong>g>in</str<strong>on</strong>g>g FRep nodes is very similar to the traditi<strong>on</strong>al approach of procedural <str<strong>on</strong>g>modell<str<strong>on</strong>g>in</str<strong>on</strong>g>g</str<strong>on</strong>g><br />
<str<strong>on</strong>g>in</str<strong>on</strong>g> Houd<str<strong>on</strong>g>in</str<strong>on</strong>g>i. FRep nodes can be classified as primitives and operati<strong>on</strong>s. In order to<br />
keep the workflow as natural as possible without forc<str<strong>on</strong>g>in</str<strong>on</strong>g>g users to adapt to new nodes, FRep<br />
Houd<str<strong>on</strong>g>in</str<strong>on</strong>g>i’s built <str<strong>on</strong>g>in</str<strong>on</strong>g> primitives Box, Sphere, Torus, C<strong>on</strong>e and Tube (called Cyl<str<strong>on</strong>g>in</str<strong>on</strong>g>der <str<strong>on</strong>g>in</str<strong>on</strong>g> the FRep<br />
API) can be used.<br />
Mak<str<strong>on</strong>g>in</str<strong>on</strong>g>g use of Houd<str<strong>on</strong>g>in</str<strong>on</strong>g>i’s native primitive nodes also enables us to reuse guide geometry and<br />
handles. Figure 4.5 shows a basic example of an ord<str<strong>on</strong>g>in</str<strong>on</strong>g>ary box and sphere be<str<strong>on</strong>g>in</str<strong>on</strong>g>g fed <str<strong>on</strong>g>in</str<strong>on</strong>g>to<br />
an FRep blend node. The FRep node at the end of the tree (frep_node6) is needed for<br />
polyg<strong>on</strong>isati<strong>on</strong> and outputt<str<strong>on</strong>g>in</str<strong>on</strong>g>g the mesh.<br />
In additi<strong>on</strong> to the already menti<strong>on</strong>ed primitive types, the <str<strong>on</strong>g>in</str<strong>on</strong>g>termediate layer (or to be more<br />
precise, the traversal algorithm described <str<strong>on</strong>g>in</str<strong>on</strong>g> Secti<strong>on</strong> 4.4.2) is also aware of the Transform<br />
SOP which can be employed for scal<str<strong>on</strong>g>in</str<strong>on</strong>g>g, translat<str<strong>on</strong>g>in</str<strong>on</strong>g>g and rotat<str<strong>on</strong>g>in</str<strong>on</strong>g>g (see Figure 4.6).<br />
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