Parameters

Description

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 $\mathit{i}$ (or $\mathit{i}$ and $\mathit{j}$) integer grid coordinates, to the $\mathit{u}$ (or $\mathit{u}$ and $\mathit{v}$) floating-point evaluation map coordinates. See glMap1 and glMap2 for details of how $\mathit{u}$ and $\mathit{v}$ 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 $\mathit{i}$ are mapped so that

glMapGrid2 specifies two such linear mappings. One maps integer grid coordinate $\mathit{i}=0$ exactly to u1, and integer grid coordinate $\mathit{i}=\mathit{un}$ exactly to u2. The other maps integer grid coordinate $\mathit{j}=0$ exactly to v1, and integer grid coordinate $\mathit{j}=\mathit{vn}$ exactly to v2. Other integer grid coordinates $\mathit{i}$ and $\mathit{j}$ are mapped such that

The mappings specified by glMapGrid are used identically by glEvalMesh and glEvalPoint.

Errors

GL_INVALID_VALUE is generated if either un or vn is not positive.

GL_INVALID_OPERATION is generated if glMapGrid is executed between the execution of glBegin and the corresponding execution of glEnd.

Associated Gets

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

See Also

glEvalCoord, glEvalMesh, glEvalPoint, glMap1, glMap2