GLMAPGRID(3G) | GLMAPGRID(3G) |
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
v=j(v2-v1)/vn+v1
The mappings specified by glMapGrid are used identically by glEvalMesh and glEvalPoint.
GL_INVALID_OPERATION is generated if glMapGrid is executed between the execution of glBegin and the corresponding execution of glEnd.