37 |
|
.br |
38 |
|
0 |
39 |
|
.PP |
40 |
< |
The syntax and semantics are nearly identical to the RADIANCE |
40 |
> |
The syntax and semantics are identical to the RADIANCE |
41 |
|
.I instance |
42 |
|
primitive, except that the mesh modifier may not be "void", since |
43 |
|
materials are not included in a compiled mesh file. |
51 |
|
Smaller values may produce faster renderings, |
52 |
|
since the default number (15) is on the high side to reduce |
53 |
|
the compiled mesh octree size. |
54 |
< |
Values below 6 are not recommended, since the median |
55 |
< |
valence (number of adjacent faces) for a mesh vertex is 6, |
56 |
< |
and smaller limits will result in pointless octree subdivision. |
54 |
> |
Values below 6 are not recommended, since this is the median |
55 |
> |
valence for a mesh vertex (the number of adjacent faces), |
56 |
> |
and smaller values will result in pointless octree subdivision. |
57 |
|
.PP |
58 |
|
The |
59 |
|
.I \-r |
70 |
|
between machines. |
71 |
|
The only limitation is that machines with radically different integer |
72 |
|
sizes will not work together. |
73 |
+ |
.SH DETAILS |
74 |
+ |
The following Wavefront statements are understood and compiled by |
75 |
+ |
.I obj2mesh. |
76 |
+ |
.TP 10n |
77 |
+ |
.BI v " x y z" |
78 |
+ |
A vertex location, given by its Cartesian coordinates. |
79 |
+ |
The final mesh position may of course be modified by |
80 |
+ |
the transform arguments given to the |
81 |
+ |
.I mesh |
82 |
+ |
primitive in the Radiance scene description. |
83 |
+ |
.TP |
84 |
+ |
.BI vn " dx dy dz" |
85 |
+ |
A vertex normal vector, given by its three |
86 |
+ |
direction components, which will be normalized by |
87 |
+ |
.I obj2mesh. |
88 |
+ |
Normals will be interpolated over the mesh |
89 |
+ |
during rendering to produce a smooth surface. |
90 |
+ |
If no vertex normals are present, the mess will appear tesselated. |
91 |
+ |
A zero length normal (i.e., 0 0 0) will generate a syntax error. |
92 |
+ |
.TP |
93 |
+ |
.BI vt " u v" |
94 |
+ |
A local vertex texture coordinate. |
95 |
+ |
These coordinates will be interpolated and passed |
96 |
+ |
to the "Lu" and "Lv" variables during rendering. |
97 |
+ |
Local coordinates can extend over any desired range of values. |
98 |
+ |
.TP |
99 |
+ |
.BI f " v1/t1/n1 v2/t2/n2 v3/t3/n3" " .." |
100 |
+ |
A polygonal face. |
101 |
+ |
Polygon vertices are specified as three indices separated |
102 |
+ |
by slashes ('/'). |
103 |
+ |
The first index is the vertex location, the |
104 |
+ |
second index is the local (u,v) texture coordinate, and the |
105 |
+ |
third index is the vertex surface normal. |
106 |
+ |
Positive indices count from the beginning of the input, |
107 |
+ |
where the first vertex position ( |
108 |
+ |
.I v |
109 |
+ |
statement) is numbered 1, and likewise |
110 |
+ |
for the first texture coordinate and the first surface normal. |
111 |
+ |
Negative indices count backward from the current position in |
112 |
+ |
the input, where -1 is the last vertex encountered, -2 |
113 |
+ |
is the one before that, etc. |
114 |
+ |
An index of 0 may be used for the vertex texture or normal to |
115 |
+ |
indicate none, or these may be left off entirely. |
116 |
+ |
All faces will be broken into triangles in the final mesh. |
117 |
+ |
.I Obj2mesh |
118 |
+ |
currently makes an unsafe assumption that faces are convex, |
119 |
+ |
which may result in odd results if they are not. |
120 |
+ |
.PP |
121 |
+ |
All other statement types will be ignored on the input. |
122 |
+ |
Statements understood by |
123 |
+ |
.I obj2rad(1) |
124 |
+ |
will be ignored silently; other statements will generate |
125 |
+ |
a warning message after translation to indicate how much was missed. |
126 |
|
.SH DIAGNOSTICS |
127 |
|
There are four basic error types reported by obj2mesh: |
128 |
|
.IP |
141 |
|
.IP "Set overflow in addobject (id)" |
142 |
|
This error occurs when too many surfaces are close together in a |
143 |
|
scene. |
144 |
< |
Sometimes a dense mesh can be accomodated by increasing |
144 |
> |
Sometimes a dense mesh can be accommodated by increasing |
145 |
|
the maximum resolution (by powers of two) using the |
146 |
|
.I \-r |
147 |
|
option, but usually this error indicates something is wrong. |
160 |
|
.SH AUTHOR |
161 |
|
Greg Ward |
162 |
|
.SH "SEE ALSO" |
163 |
< |
gensurf(1), getinfo(1), make(1), |
163 |
> |
gensurf(1), getinfo(1), make(1), obj2rad(1), |
164 |
|
oconv(1), rpict(1), rview(1), rtrace(1), xform(1) |