TEXTUREPROJLOD(3G)

💖 textureProjLod — the projected texture lookup with explicit LOD, bestie 💖

okay so this is a page from the 3G manual, and honestly? it's a whole vibe. it's the textureProjLod era of your shader life and we're gonna get through it together, no cap ✨

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🌸 NAME 🌸

textureProjLod — perform a texture lookup with projection and explicit level-of-detail

like, you're sampling a texture, but you're also projecting, and you're telling it which LOD to use instead of letting it guess. main character behavior tbh 👑

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🎀 DECLARATION 🎀

the whole squad of overloads, verbatim, don't touch a single character:

gvec4 textureProjLod(gsampler1D sampler, vec2 P, float lod);

gvec4 textureProjLod(gsampler1D sampler, vec4 P, float lod);

gvec4 textureProjLod(gsampler2D sampler, vec3 P, float lod);

gvec4 textureProjLod(gsampler2D sampler, vec4 P, float lod);

gvec4 textureProjLod(gsampler3D sampler, vec4 P, float lod);

float textureProjLod(sampler1DShadow sampler, vec4 P, float lod);

float textureProjLod(sampler2DShadow sampler, vec4 P, float lod);

seven of them. seven little icons. and every single one ate 💅

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🦋 PARAMETERS 🦋

• sampler — the sampler that's got the texture you're pulling texels out of all bound up in it. it's the plug, fr.
• P — the texture coordinates where the sampling is gonna happen. where we're looking, bestie.
• lod — the explicit level-of-detail you're fetching texels from. you're not asking the universe to pick, you're picking. assertive. love that for you.

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✨ DESCRIPTION ✨

so textureProjLod does a texture lookup with projection, and it does it from an explicitly specified level-of-detail. key words: explicitly specified. no guessing games 💀

here's the tea on the math, and it's lowkey the whole plot twist:

• the texture coordinates consumed from P — and note that this is not including the last component of P — get divided by the last component of P. that's the projection, that's the move 🫶
• the resulting 3rd component of P in the shadow forms is used as Dref. yes, shadow forms get a Dref out of it. that's just what happens.
• once all that's computed, the texture lookup proceeds as in textureLod(), with lod used to specify the level-of-detail from which the texture will be sampled.

so: divide, get your Dref if you're shadow-coded, then hand it off to the textureLod() pipeline like a relay baton. iconic 🌈

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⭐ VERSION SUPPORT ⭐

the original page ships this as a big grid, and we are not losing a single cell of it. here's the whole thing, version by version, for textureProjLod:

• OpenGL Shading Language Version 1.10 — - (nope, not yet 🙈)
• OpenGL Shading Language Version 1.20 — - (still nope 🙈)
• OpenGL Shading Language Version 1.30 — ✔ (it's here!! 🎉)
• OpenGL Shading Language Version 1.40 — ✔
• OpenGL Shading Language Version 1.50 — ✔
• OpenGL Shading Language Version 3.30 — ✔
• OpenGL Shading Language Version 4.00 — ✔
• OpenGL Shading Language Version 4.10 — ✔
• OpenGL Shading Language Version 4.20 — ✔
• OpenGL Shading Language Version 4.30 — ✔
• OpenGL Shading Language Version 4.40 — ✔
• OpenGL Shading Language Version 4.50 — ✔

so basically it showed up in 1.30 and never left. loyal. committed. that's a bestie 💜

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👑 SEE ALSO 👑

go read these too, they're all in the group chat:

texelFetch(), texelFetchOffset(), texture(), textureGather(), textureGatherOffset(), textureGatherOffsets(), textureGrad(), textureGradOffset(), textureLod(), textureLodOffset(), textureOffset(), textureProj(), textureProjGrad(), textureProjGradOffset(), 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/.

Copyright © 2011-2014 Khronos Group

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aaaand that's the page, bestie 🎀 source was marked [FIXME: source], dated 01/03/2018, and the whole thing lives under the 3G manual. go project something gorgeous. mwah 💅🌸