Name
gl.MapGrid -- define a one- or two-dimensional mesh
Synopsis
gl.MapGrid(un, u1, u2[, vn, v1, v2])
Function
gl.MapGrid() and gl.EvalMesh() are used together to efficiently generate and evaluate a series of evenly-spaced map domain values. gl.EvalMesh() steps through the integer domain of a one- or two-dimensional grid, whose range is the domain of the evaluation maps specified by gl.Map().

gl.MapGrid() specifies 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 gl.Map for details of how u and v coordinates are evaluated.

In one-dimensional mode, gl.MapGrid() 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

In two-dimensional mode gl.MapGrid() 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 gl.MapGrid() are used identically by gl.EvalMesh() and gl.EvalPoint().

Please consult an OpenGL reference manual for more information.

Inputs
un
specifies the number of partitions in the grid range interval [u1, u2]; must be positive
u1
specify the mappings for integer grid domain values i = 0 and i = un
u2
specify the mappings for integer grid domain values i = 0 and i = un
vn
optional: specifies the number of partitions in the grid range interval [v1, v2]
v1
optional: specify the mappings for integer grid domain values j = 0 and j = vn
v2
optional: specify the mappings for integer grid domain values j = 0 and j = vn
Errors
#GL_INVALID_VALUE is generated if either un or vn is not positive.

#GL_INVALID_OPERATION is generated if gl.MapGrid() is executed between the execution of gl.Begin() and the corresponding execution of gl.End().

Associated gets
gl.Get() with argument #GL_MAP1_GRID_DOMAIN

gl.Get() with argument #GL_MAP2_GRID_DOMAIN

gl.Get() with argument #GL_MAP1_GRID_SEGMENTS

gl.Get() with argument #GL_MAP2_GRID_SEGMENTS


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