GLEVALPOINT(3G)

💖 GLEVALPOINT(3G) — glEvalPoint1, glEvalPoint2 💖

okay bestie, welcome to the 3G manual page for glEvalPoint1 and glEvalPoint2 ✨ these two are literally the "just gimme ONE point" girlies of the mesh world. let's get into it 🫶

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✨ NAME ✨

glEvalPoint1, glEvalPoint2 — generate and evaluate a single point in a mesh

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🌸 C SPECIFICATION 🌸

void glEvalPoint1( GLint i )
void glEvalPoint2( GLint i,
                   GLint j )

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🎀 PARAMETERS 🎀

• i — Specifies the integer value for grid domain variable i.
• j — Specifies the integer value for grid domain variable j (glEvalPoint2 only).

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🦋 DESCRIPTION 🦋

so here's the vibe: glMapGrid and glEvalMesh are used in tandem to efficiently generate and evaluate a series of evenly spaced map domain values. and glEvalPoint can be used to evaluate a single grid point in the same gridspace that is traversed by glEvalMesh 👑 (yes, the same gridspace, no cap).

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. and the one absolute numeric requirement — like, the ONE thing you cannot fumble — is that if i=n, then the value computed from i⋅Δu+u1 is exactly u2. exactly. not "close enough", not "bestie it's basically the same". EXACTLY. 💅

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 i⋅Δv+v1 is exactly v2. ✨ two requirements, both absolute, both exact. the math does not do vibes-based rounding, she does precision. 🧚

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⭐ 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

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🌈 SEE ALSO 🌈

glEvalCoord(3G), glEvalMesh(3G), glMap1(3G), glMap2(3G), glMapGrid(3G)

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and that's the whole page, bestie!! 🥳 this one's from the GLEVALPOINT(3G) manual page, and the footer just says GLEVALPOINT(3G) again with no extra version or date info to spill — so consider this your cute lil sign-off: go forth and evaluate exactly one point at a time, no more no less 💜🌸🍓