TEXTUREPROJGRAD(3G)

💖 TEXTUREPROJGRAD(3G) 💖

okay bestie, welcome to textureProjGrad — it lives in the 3G section of the manual (the [FIXME: manual] one, yes, we're all doing our best here 🫶), and it is exactly what it sounds like: a texture lookup, but with projection AND you hand it the gradients yourself. main character energy fr fr.

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✨ NAME ✨

textureProjGrad — perform a texture lookup with projection and explicit gradients 💅

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🌸 DECLARATION 🌸

here's the whole roster, no cap, copied verbatim so you don't have to squint at the spec:

gvec4 textureProjGrad(gsampler1D sampler, vec2 P, float pDx, float pDy);

gvec4 textureProjGrad(gsampler1D sampler, vec4 P, float pDx, float pDy);

gvec4 textureProjGrad(gsampler2D sampler, vec3 P, vec2 pDx, vec2 pDy);

gvec4 textureProjGrad(gsampler2D sampler, vec4 P, vec2 pDx, vec2 pDy);

gvec4 textureProjGrad(gsampler3D sampler, vec4 P, vec3 pDx, vec3 pDy);

float textureProjGrad(sampler1DShadow sampler, vec4 P, float pDx,
                      float pDy);

float textureProjGrad(sampler2DShadow sampler, vec4 P, vec2 pDx,
                      vec2 pDy);

gvec4 textureProjGrad(gsampler2DRect sampler, vec3 P, vec2 pDx,
                      vec2 pDy);

gvec4 textureProjGrad(gsampler2DRect sampler, vec4 P, vec2 pDx,
                      vec2 pDy);

float textureProjGrad(gsampler2DRectShadow sampler, vec4 P, vec2 pDx,
                      vec2 pDy);

like, ten whole overloads. she's versatile. 👑

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🎀 PARAMETERS 🎀

• sampler — the sampler your texture is bound to, aka where the texels are coming from. she's the plug. 🍓
• P — the texture coordinates where we're sampling. the "where tho" of the whole operation.
• dPdx — the partial derivative of P with respect to window x. yes girl, calculus. we're doing calculus.
• dPdy — the partial derivative of P with respect to window y. the sibling. the other axis. iconic duo. ✨

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🦋 DESCRIPTION 🦋

so textureProjGrad does a texture lookup with projection and explicit gradients. two things at once, multitasking queen.

the way it works: the texture coordinates consumed from P — and not including the last component of P, mind you — get divided by the last component of P. classic projection behaviour, we love her.

then, for the shadow forms, that resulting 3rd component of P gets used as Dref. 💅

once all of that is computed, the lookup just proceeds exactly like textureGrad(), and you pass dPdx and dPdy in as the gradients. that's it. that's the whole vibe. periodt.

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🌈 VERSION SUPPORT 🌈

the original was a big fancy table (rip tables, you were so grid-shaped), so here it is as a glow-up list. the columns were the OpenGL Shading Language Version, going 1.10, 1.20, 1.30, 1.40, 1.50, 3.30, 4.00, 4.10, 4.20, 4.30, 4.40, 4.50 — in that order, bestie:

• textureProjGrad — 1.10 ✗, 1.20 ✗, 1.30 ✔, 1.40 ✔, 1.50 ✔, 3.30 ✔, 4.00 ✔, 4.10 ✔, 4.20 ✔, 4.30 ✔, 4.40 ✔, 4.50 ✔
• textureProjGrad (gsampler2DRect{Shadow}) — 1.10 ✗, 1.20 ✗, 1.30 ✗, 1.40 ✔, 1.50 ✔, 3.30 ✔, 4.00 ✔, 4.10 ✔, 4.20 ✔, 4.30 ✔, 4.40 ✔, 4.50 ✔

so the rect-shadow flavour showed up late to the party (hi 1.40 💖) and the regular one has been here since 1.30. glow-ups all around.

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👑 SEE ALSO 👑

your homework, bestie — all of these, exactly as written:

texelFetch(), texelFetchOffset(), texture(), textureGather(), textureGatherOffset(), textureGatherOffsets(), textureGrad(), textureGradOffset(), textureLod(), textureLodOffset(), textureOffset(), textureProj(), textureProjGradOffset(), textureProjLod(), textureProjLodOffset(), textureProjOffset(), textureQueryLod(), textureSize()

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💜 COPYRIGHT 💜

Copyright © 2011-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.

and, once more with feeling (the original literally prints it twice, so we do too, no skipping 🫶):

Copyright © 2011-2014 Khronos Group

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okay that's the whole page, you ate that. mwah. 💅✨

cute little sign-off: this came from the [FIXME: source] of the TEXTUREPROJGRAD(3G) manual, dated 01/03/2018. stan Khronos. bye bestie 🦋💖