glEvalPoint1, glEvalPoint2 - generate and evaluate a single point in a mesh
void glEvalPoint1( GLint i ) void glEvalPoint2( GLint i, GLint j )
i Specifies the integer value for grid domain variable i. j Specifies the integer value for grid domain variable j (glEvalPoint2 only).
glMapGrid and glEvalMesh are used in tandem to efficiently generate and evaluate a series of evenly spaced map domain values. glEvalPoint can be used to evaluate a single grid point in the same gridspace that is traversed by glEvalMesh. Calling glEvalPoint1 is equivalent to calling glEvalCoord1(i�du + u ); 1 where du = (u -u )/n 2 1 and n, u , and u are the arguments to the most recent glMapGrid1 command. 1 2 The one absolute numeric requirement is that if i = n, then the value computed from i�du + u is exactly u . 1 2 In the two-dimensional case, glEvalPoint2, let du=(u -u )/n 2 1 dv=(v -v )/m 2 1 where n, u , u , m, v , and v are the arguments to the most recent 1 2 1 2 glMapGrid2 command. Then the glEvalPoint2 command is equivalent to calling glEvalCoord2(i�du + u , j�dv + v ); 1 1 The only absolute numeric requirements are that if i = n, then the value computed from i�du + u is exactly u , and if j = m, then the value 1 2 computed from j�dv + v is exactly v . 1 2
glGet with argument GL_MAP1_GRID_DOMAIN glGet with argument GL_MAP2_GRID_DOMAIN glGet with argument GL_MAP1_GRID_SEGMENTS glGet with argument GL_MAP2_GRID_SEGMENTS
glEvalCoord, glEvalMesh, glMap1, glMap2, glMapGrid
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Last Edited:
Fri Dec 6 11:18:03 EST 1996
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AFV
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