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⋅Δu + u₁);
where
Δu = (u₂ − u₁) / 𝐧
and 𝐧, u₁, and u₂ are the arguments to the most recent glMapGrid1 command. The one absolute numeric requirement is that if i = 𝐧, then the value computed from i⋅Δu + u₁ is exactly u₂.
In the two-dimensional case, glEvalPoint2, let
Δu = (u₂ − u₁) / 𝐧
Δv = (v₂ − v₁) / 𝐦
where 𝐧, u₁, u₂, 𝐦, v₁, and v₂ are the arguments to the most recent glMapGrid2 command. Then the glEvalPoint2 command is equivalent to calling
glEvalCoord2(i⋅Δu + u₁, j⋅Δv + v₁);
The only absolute numeric requirements are that if i = 𝐧, then the value computed from i⋅Δu + u₁ is exactly u₂, and if j = 𝐦, then the value computed from j⋅Δv + v₁ is exactly v₂.
Parameters
i: number
Specifies the integer value for grid domain variable i.
j: number
Specifies the integer value for grid domain variable j.
glMapGrid and glEvalMesh are used in tandem to efficiently generate and evaluate a series of evenly spaced map domain values.
glEvalPointcan be used to evaluate a single grid point in the same gridspace that is traversed by glEvalMesh. CallingglEvalPoint1is equivalent to callingglEvalCoord1 (i⋅Δu + u₁);where
Δu = (u₂ − u₁) / 𝐧
and 𝐧, u₁, and u₂ are the arguments to the most recent glMapGrid1 command. The one absolute numeric requirement is that if i = 𝐧, then the value computed from i⋅Δu + u₁ is exactly u₂.
In the two-dimensional case,
glEvalPoint2, letΔu = (u₂ − u₁) / 𝐧
Δv = (v₂ − v₁) / 𝐦
where 𝐧, u₁, u₂, 𝐦, v₁, and v₂ are the arguments to the most recent glMapGrid2 command. Then the
glEvalPoint2command is equivalent to callingglEvalCoord2(i⋅Δu + u₁, j⋅Δv + v₁);The only absolute numeric requirements are that if i = 𝐧, then the value computed from i⋅Δu + u₁ is exactly u₂, and if j = 𝐦, then the value computed from j⋅Δv + v₁ is exactly v₂.