1Tdpack_params(3NCARG) NCAR GRAPHICS Tdpack_params(3NCARG)
2
6 Tdpack_params - This document briefly describes all internal parameters
7 of Tdpack.
8
10 Tdpack currently supports some fifteen parameters. The current values
11 may be retrieved using one of the routines TDGETI, TDGETR, or TDGTRS.
12 Parameter values may be reset using one of the routines TDSETI, TDSETR,
13 or TDSTRS.
14 The Tdpack parameter descriptions appear below in alphabetical order.
16 Each description begins with a line giving the parameter name and the
17 intrinsic FORTRAN type of the parameter.
18 'CS1' - Real
20 Character Size 1. This is a multiplier for the sizes of all
21 characters drawn by the routine TDLBLS.
22 The default value of 'CS1' is 1.
24 'CS2' - Real
26 Character Size 2. This is a multiplier for the sizes of all
27 characters drawn by the routine TDLBLA. Exactly how it is set
28 depends on how the current reference parallelogram has been
29 defined. If the current reference parallelogram has sides of
30 length 1, then it is appropriate to set
31 'CS2'='CS1'*MIN(UMAX-UMIN,VMAX-VMIN,WMAX-WMIN)
33 where UMIN, UMAX, VMIN, VMAX, WMIN, and WMAX are defined like
35 the arguments of TDLBLS. Note that, if you call TDLBLS, it
36 resets 'CS2' in this fashion, and it does not restore the
37 original value before return.
38 The default value of 'CS2' is 1.
40 'FOV' - Real
42 When 'SET' has a non-zero value, specifying that TDINIT is to
43 call the SPPS routine SET, then 'FOV' specifies the desired
44 field of view, in degrees, to be seen in the projection plane;
45 its value is used to compute appropriate values for the
46 arguments in the call to SET.
47 The default value of 'FOV' is 20.
49 'HND' - Integer
51 A zero value specifies that the UVW coordinate system is to be
52 right-handed (the default), while a non-zero value says that it
53 is to be left-handed. Changing the value of 'HND' mostly
54 affects the behavior of TDINIT - it changes the values of the
55 projection coefficients precomputed and stored in TDPACK common
56 blocks - but it also affects the behavior of the routines TDDTRI
57 and TDLBLS; for this reason, you should not change the value of
58 'HND' between a call to TDINIT and an ensuing call to one of the
59 other two routines, as this would lead to inconsistent behavior.
60 (Most likely, you will decide what the handedness of your
61 coordinate system is, change the value of 'HND' accordingly, and
62 leave that value unchanged thereafter.)
63 The default value of 'HND' is 0, specifying a right-handed
65 coordinate system.
66 'LSU', 'LSV', and 'LSW' - Real
68 If one or more of these three values is non-zero, then the
69 3-space point ('LSU','LSV','LSW') is the position of the light
70 source assumed by TDDTRI in rendering the triangles in the
71 triangle list.
72 The default values are all 0., which, by convention, specifies a
74 light source at the position (UMID,VMID,WMID), where UMID, VMID,
75 and WMID are as specified in the last call to TDINIT.
76 'SET' - Integer
78 If this flag is equal to 1 (the default), calling TDINIT will
79 result in a call to the SPPS routine SET to define the mapping
80 from the "user coordinate system" (the X/Y projection plane) to
81 the "fractional coordinate system" (the same as the GKS NDC
82 space); that call will be done in such a way as to give a field
83 of view of 'FOV' degrees and to use the portion of the plotter
84 frame defined by the internal parameters 'VPL', 'VPR', 'VPB',
85 and 'VPT'. If 'SET' is given the value 0, no such call to SET
86 will be done and the user will be expected to have called it.
87 In the future, other non-zero values of 'SET' may be implemented
88 which will result in TDINIT's doing a call to SET according to
89 some other criterion.
90 The default value of 'SET' is 1, specifying that a SET call
92 should be done by TDINIT.
93 'SHD' - Integer
95 The value of 'SHD' affects the behavior of TDDTRI when it is
96 picking the fill color to be used for a triangle and the
97 rendering style for the triangle implies that the color index is
98 to be chosen by computing the angle between two vectors - the
99 normal to the triangle and the vector from its center to the
100 light source - and then mapping that angle into a specified
101 range of color indices (thus shading the surface).
102 If the value of 'SHD' is zero, angles between 0 and 90 are
104 mapped linearly into the specified range of color indices, from
105 lowest to highest, while angles between 90 and 180 are mapped
106 linearly into that same range, from highest to lowest. The
107 effect of this is essentially to use two light sources, one at
108 the position ('LSU','LSV','LSW') and the other at an exactly
109 opposite position relative to the center of the triangle.
110 If the value of 'SHD' is non-zero, angles between 0 and 180 are
112 mapped linearly into the specified range of color indices, from
113 lowest to highest. The effect of this is essentially to use a
114 single light source, at the position ('LSU','LSV','LSW').
115 Note that, in both cases, it is the user's responsibility to
117 define the colors associated with the color indices in the
118 specified range to achieve the desired effect. (Normally, the
119 colors associated with the beginning of the range of color
120 indices should be the lightest and the colors associated with
121 the end of that range should be the darkest.) For help in
122 defining colors, see the code of the examples.
123 The default value of 'SHD' is zero.
125 'STE' - Integer
127 When 'STE' is zero (the default), then stereo pairs are drawn
128 using a single image plane which is perpendicular to the line
129 joining a point midway between the eyes to the point looked at.
130 If 'STE' is set non-zero, then the view from each eye is drawn
131 using an image plane which is perpendicular to the line joining
132 that eye to the point looked at. (In practice, this probably
133 makes little difference.)
134 Changing this parameter changes the values of the projection
136 coefficients precomputed by TDINIT and stored in TDPACK common
137 blocks.
138 The default value of 'STE' is 0, specifying that stereo pairs
140 should be drawn using a single image plane perpendicular to the
141 line from the midpoint of the eyes to the point looked at.
142 'VPB', 'VPL', 'VPR', and 'VPT' - Real
144 The values of these parameters specify the positions of the
145 bottom, left, right, and top edges, respectively, of a desired
146 viewport within the plotter frame. Each is given a value between
147 0 and 1, inclusive, specifying the position as a fraction of the
148 distance across the plotter frame from left to right or from
149 bottom to top.
150 These values are used when the SPPS routine SET is called by
152 TDINIT (which happens when the internal parameter 'SET' has a
153 non-zero value).
154 The default values of 'VPB', 'VPL', 'VPR', and 'VPT' are .05,
156 .05, .95, and .95, respectively, specifying the use of most of
157 the plotter frame.
158 'Rendering-Style arrays' - Integer
160 The internal parameter arrays that define rendering styles are
161 accessed using the routines TDGTRS (to get the complete
162 definition of a specific rendering style) and TDSTRS (to
163 redefine a specific rendering style). Sixty-four different
164 rendering styles may be defined, indexed 1 through 64; each is
165 defined by an array of ten quantities, seven of which are of
166 type INTEGER (named IFC1, IFC2, IFC3, IFC4, ILC1, ILC2, and
167 ILTD) and three of which are of type REAL (named USTP, VSTP, and
168 WSTP). These quantities may be described as follows:
169 IFC1 and IFC2 are color indices specifying a range of
171 colors to be used for the "bottom" side of a surface
172 (where function values are less than the value on the
173 surface). If IFC1 is negative, filling of triangles seen
174 from the "bottom" is turned off. If IFC1 is zero or
175 greater, but IFC2 is less than or equal to it, the color
176 with index IFC1 is used. If IFC1 is zero or greater and
177 IFC2 is greater than IFC1, then a range of color indices
178 is specified; colors near the beginning of that range are
179 used for triangles that are nearly perpendicular to the
180 line of sight, while colors near the end of that range
181 are used for triangles more nearly parallel to the line
182 of sight. (Normally, one should make triangles
183 perpendicular to the line of sight lighter than those
184 parallel to the line of sight.)
185 IFC3 and IFC4 are color indices specifying a range of
187 colors to be used for the "top" side of a surface (where
188 function values are greater than the value on the
189 surface). If IFC3 is negative, filling of triangles seen
190 from the "top" is turned off. If IFC3 is zero or greater,
191 but IFC4 is less than or equal to it, the color with
192 index IFC3 is used. If IFC3 is zero or greater and IFC4
193 is greater than IFC3, then a range of color indices is
194 specified; colors near the beginning of that range are
195 used for triangles that are nearly perpendicular to the
196 line of sight, while colors near the end of that range
197 are used for triangles more nearly parallel to the line
198 of sight. (Normally, one should make triangles
199 perpendicular to the line of sight lighter than those
200 parallel to the line of sight.)
201 ILC1 is the color index specifying a color to be used for
203 lines drawn on the "bottom" side of a surface. If ILC1 is
204 negative, the drawing of these lines is turned off.
205 ILC2 is the color index specifying a color to be used for
207 lines drawn on the "top" side of a surface. If ILC2 is
208 negative, the drawing of these lines is turned off.
209 ILTD is a flag, which, if set non-zero, turns on the
211 drawing of the edges of the individual triangles into
212 which surfaces have been decomposed.
213 USTP, VSTP, and WSTP are the distances between slices in
215 the U, V, and W directions, respectively. If a given
216 value is zero, the associated slice lines are not drawn.
217 Note: It is the responsibility of the user to call the
219 GKS routine GSCR to define all of the colors to be used.
220
222 Online: tdclrs, tdctri, tddtri, tdgeti, tdgetr, tdgrds, tdgrid, tdgtrs,
223 tdinit, tditri, tdlbla, tdlbls, tdline, tdlnpa, tdmtri, tdotri, tdpack,
224 tdpara, tdplch, tdprpa, tdprpi, tdprpt, tdseti, tdsetr, tdsort, tdstri,
225 tdstrs
226
228 Copyright (C) 1987-2009
229 University Corporation for Atmospheric Research
230 The use of this Software is governed by a License Agreement.
231UNIX July 1997 Tdpack_params(3NCARG)