1GLEVALPOINT(3G)                  OpenGL Manual                 GLEVALPOINT(3G)
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NAME

6       glEvalPoint - generate and evaluate a single point in a mesh
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C SPECIFICATION

9       void glEvalPoint1(GLint i);
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11       void glEvalPoint2(GLint i, GLint j);
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PARAMETERS

14       i
15           Specifies the integer value for grid domain variable i.
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17       j
18           Specifies the integer value for grid domain variable j
19           (glEvalPoint2 only).
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DESCRIPTION

22       glMapGrid() and glEvalMesh() are used in tandem to efficiently generate
23       and evaluate a series of evenly spaced map domain values.  glEvalPoint
24       can be used to evaluate a single grid point in the same gridspace that
25       is traversed by glEvalMesh(). Calling glEvalPoint1 is equivalent to
26       calling
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28           glEvalCoord1(
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30
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32                                       i
33                                       ⋅
34                                       Δ
35                                       u
36
37                                   +
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39                                       u
40                                       1
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42
43                          );
44
45
46       where Δ u = u 2 - u 1 n
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48       and n, u 1, and u 2 are the arguments to the most recent glMapGrid1()
49       command. The one absolute numeric requirement is that if i = n, then
50       the value computed from i ⋅ Δ u + u 1 is exactly u 2.
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52       In the two-dimensional case, glEvalPoint2, let
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54       Δ u = u 2 - u 1 n
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56       where n, u 1, u 2, m, v 1, and v 2 are the arguments to the most recent
57       glMapGrid2() command. Then the glEvalPoint2 command is equivalent to
58       calling
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60           glEvalCoord2(
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62
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64                                  i
65                               ⋅
66                                  Δ
67                                     u
68
69                                 +
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71                                     u
72                                     1
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74                              ,
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76
77                                  j
78                               ⋅
79                                  Δ
80                                     v
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82
83                                 +
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85                                     v
86                                     1
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89                          );
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91
92       The only absolute numeric requirements are that if i = n, then the
93       value computed from i ⋅ Δ u + u 1 is exactly u 2, and if j = m, then
94       the value computed from j ⋅ Δ v + v 1 is exactly v 2.
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ASSOCIATED GETS

97       glGet() with argument GL_MAP1_GRID_DOMAIN
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99       glGet() with argument GL_MAP2_GRID_DOMAIN
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101       glGet() with argument GL_MAP1_GRID_SEGMENTS
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103       glGet() with argument GL_MAP2_GRID_SEGMENTS
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SEE ALSO

106       glEvalCoord(), glEvalMesh(), glMap1(), glMap2(), glMapGrid()
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109       Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
110       under the SGI Free Software B License. For details, see
111       http://oss.sgi.com/projects/FreeB/.
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AUTHORS

114       opengl.org
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118opengl.org                        07/13/2018                   GLEVALPOINT(3G)
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