man/man1/gensurf.1

.\" RCSid "$Id"
.TH GENSURF 1 11/15/93 RADIANCE
.SH NAME
gensurf - generate a RADIANCE or Wavefront description of a curved surface
.SH SYNOPSIS
.B "gensurf mat name 'x(s,t)' 'y(s,t)' 'z(s,t)' m n"
[
.B "\-e expr"
][
.B "\-f file"
][
.B \-s
][
.B \-o
]
.br
.B "gensurf mat name 'x(s,t)' 'y(s,t)' dfile m n"
[
.B "\-e expr"
][
.B "\-f file"
][
.B \-s
][
.B \-o
]
.br
.B "gensurf mat name dfile dfile dfile m n"
[
.B \-s
][
.B \-o
]
.SH DESCRIPTION
.I Gensurf
produces either a RADIANCE scene description or a Wavefront .OBJ
file of a functional surface defined by the parametric equations
.I x(s,t),
.I y(s,t),
and
.I z(s,t).
The surface normal is defined by the right hand rule as
applied to
.I (s,t).
.I S
will vary from 0 to 1 in steps of
.I 1/m,
and
.I t
will vary from 0 to 1 in steps of
.I 1/n.
The surface will be composed of
.I 2*m*n
or fewer triangles and quadrilaterals.
The expressions are of the same type used in RADIANCE
function files.
Auxiliary expressions and/or files may be specified
in any number of
.I \-e
and
.I \-f
options.
The
.I \-s
option adds smoothing (surface normal interpolation) to the surface.
The
.I \-o
option produces a Wavefront .OBJ file rather than a RADIANCE
scene description.
This is most useful as input to the
.I obj2mesh(1)
program for producing a compiled mesh.
.PP
Rough holes may be cut in the mesh by defining a valid(s,t) function.
Where this function is positive, polygon vertices will be produced.
Where it is negative, no geometry will be output.
Surface normal interpolation will ignore any invalid vertices.
.PP
The second invocation form reads z data values from the file
.I dfile.
This file must give either m*n or (m+1)*(n+1) floating point z
values.
If m*n values are given, then the values correspond to the centroid
of each quadrilateral region.
If (m+1)*(n+1) values are given, then the values correspond to the
vertices of each quadrilateral region.
The ordering of the data in the file is such that the s values are
changing faster than the t values.
If a minus ('-') is given for
.I dfile,
then the values are read from the standard input.
.PP
The third invocation form is used to read coordinate triplets from a
file or the standard input.
The three
.I dfile
arguments must all be the same, and the corresponding file must
contain three floating point values for each point location.
The ordering and other details are the same as those described
for z value files above.
.SH EXAMPLE
To generate a tesselated sphere:
.IP "" .2i
gensurf crystal ball 'sin(PI*s)*cos(2*PI*t)' 'cos(PI*s)' 'sin(PI*s)*sin(2*PI*t)' 7 10
.PP
To generate a 10x20 smoothed height field from 12 recorded vertex
z values:
.IP "" .2i
gensurf dirt ground '10*s' '20*t' height.dat 2 3 -s
.SH AUTHOR
Greg Ward
.SH BUGS
The smoothing operation requires that functions be defined
beyond the [0,1] boundaries of s and t.
.SH "SEE ALSO"
calc(1), genbox(1), genrev(1), genworm(1),
obj2mesh(1), rpict(1), rview(1), xform(1)
Revision:	1.2
Committed:	Tue Mar 11 22:48:20 2003 UTC (21 years, 3 months ago) by greg
Branch:	MAIN
Changes since 1.1:	+18 -4 lines
Log Message:	Created man page for obj2mesh and added -o option to gensurf
#	Content
1	.\" RCSid "$Id"
2	.TH GENSURF 1 11/15/93 RADIANCE
3	.SH NAME
4	gensurf - generate a RADIANCE or Wavefront description of a curved surface
5	.SH SYNOPSIS
6	.B "gensurf mat name 'x(s,t)' 'y(s,t)' 'z(s,t)' m n"
7	[
8	.B "\-e expr"
9	][
10	.B "\-f file"
11	][
12	.B \-s
13	][
14	.B \-o
15	]
16	.br
17	.B "gensurf mat name 'x(s,t)' 'y(s,t)' dfile m n"
18	[
19	.B "\-e expr"
20	][
21	.B "\-f file"
22	][
23	.B \-s
24	][
25	.B \-o
26	]
27	.br
28	.B "gensurf mat name dfile dfile dfile m n"
29	[
30	.B \-s
31	][
32	.B \-o
33	]
34	.SH DESCRIPTION
35	.I Gensurf
36	produces either a RADIANCE scene description or a Wavefront .OBJ
37	file of a functional surface defined by the parametric equations
38	.I x(s,t),
39	.I y(s,t),
40	and
41	.I z(s,t).
42	The surface normal is defined by the right hand rule as
43	applied to
44	.I (s,t).
45	.I S
46	will vary from 0 to 1 in steps of
47	.I 1/m,
48	and
49	.I t
50	will vary from 0 to 1 in steps of
51	.I 1/n.
52	The surface will be composed of
53	.I 2mn
54	or fewer triangles and quadrilaterals.
55	The expressions are of the same type used in RADIANCE
56	function files.
57	Auxiliary expressions and/or files may be specified
58	in any number of
59	.I \-e
60	and
61	.I \-f
62	options.
63	The
64	.I \-s
65	option adds smoothing (surface normal interpolation) to the surface.
66	The
67	.I \-o
68	option produces a Wavefront .OBJ file rather than a RADIANCE
69	scene description.
70	This is most useful as input to the
71	.I obj2mesh(1)
72	program for producing a compiled mesh.
73	.PP
74	Rough holes may be cut in the mesh by defining a valid(s,t) function.
75	Where this function is positive, polygon vertices will be produced.
76	Where it is negative, no geometry will be output.
77	Surface normal interpolation will ignore any invalid vertices.
78	.PP
79	The second invocation form reads z data values from the file
80	.I dfile.
81	This file must give either mn or (m+1)(n+1) floating point z
82	values.
83	If m*n values are given, then the values correspond to the centroid
84	of each quadrilateral region.
85	If (m+1)*(n+1) values are given, then the values correspond to the
86	vertices of each quadrilateral region.
87	The ordering of the data in the file is such that the s values are
88	changing faster than the t values.
89	If a minus ('-') is given for
90	.I dfile,
91	then the values are read from the standard input.
92	.PP
93	The third invocation form is used to read coordinate triplets from a
94	file or the standard input.
95	The three
96	.I dfile
97	arguments must all be the same, and the corresponding file must
98	contain three floating point values for each point location.
99	The ordering and other details are the same as those described
100	for z value files above.
101	.SH EXAMPLE
102	To generate a tesselated sphere:
103	.IP "" .2i
104	gensurf crystal ball 'sin(PIs)cos(2PIt)' 'cos(PIs)' 'sin(PIs)sin(2PI*t)' 7 10
105	.PP
106	To generate a 10x20 smoothed height field from 12 recorded vertex
107	z values:
108	.IP "" .2i
109	gensurf dirt ground '10s' '20t' height.dat 2 3 -s
110	.SH AUTHOR
111	Greg Ward
112	.SH BUGS
113	The smoothing operation requires that functions be defined
114	beyond the [0,1] boundaries of s and t.
115	.SH "SEE ALSO"
116	calc(1), genbox(1), genrev(1), genworm(1),
117	obj2mesh(1), rpict(1), rview(1), xform(1)