glMapGrid and glEvalMesh are used together to efficiently generate and evaluate a series of evenly-spaced map domain values. glEvalMesh steps through the integer domain of a one- or two-dimensional grid, whose range is the domain of the evaluation maps specified by glMap1 and glMap2. glMapGrid1 and glMapGrid2 specify the linear grid mappings between the i (or i and j ) integer grid coordinates, to the u (or u and v ) floating-point evaluation map coordinates. See glMap1 and glMap2 for details of how u and v coordinates are evaluated. glMapGrid1 specifies a single linear mapping such that integer grid coordinate 0 maps exactly to u1, and integer grid coordinate un maps exactly to u2. All other integer grid coordinates i are mapped so that u = i ⁡ u2 - u1 un + u1 glMapGrid2 specifies two such linear mappings. One maps integer grid coordinate i = 0 exactly to u1, and integer grid coordinate i = un exactly to u2. The other maps integer grid coordinate j = 0 exactly to v1, and integer grid coordinate j = vn exactly to v2. Other integer grid coordinates i and j are mapped such that u = i ⁡ u2 - u1 un + u1 v = j ⁡ v2 - v1 vn + v1 The mappings specified by glMapGrid are used identically by glEvalMesh and glEvalPoint.
Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.
glMapGrid: man2/glMapGrid.xml
glMapGrid and glEvalMesh are used together to efficiently generate and evaluate a series of evenly-spaced map domain values. glEvalMesh steps through the integer domain of a one- or two-dimensional grid, whose range is the domain of the evaluation maps specified by glMap1 and glMap2. glMapGrid1 and glMapGrid2 specify the linear grid mappings between the i (or i and j ) integer grid coordinates, to the u (or u and v ) floating-point evaluation map coordinates. See glMap1 and glMap2 for details of how u and v coordinates are evaluated. glMapGrid1 specifies a single linear mapping such that integer grid coordinate 0 maps exactly to u1, and integer grid coordinate un maps exactly to u2. All other integer grid coordinates i are mapped so that u = i ⁡ u2 - u1 un + u1 glMapGrid2 specifies two such linear mappings. One maps integer grid coordinate i = 0 exactly to u1, and integer grid coordinate i = un exactly to u2. The other maps integer grid coordinate j = 0 exactly to v1, and integer grid coordinate j = vn exactly to v2. Other integer grid coordinates i and j are mapped such that u = i ⁡ u2 - u1 un + u1 v = j ⁡ v2 - v1 vn + v1 The mappings specified by glMapGrid are used identically by glEvalMesh and glEvalPoint.