vpTranspose(3)

💅 vpTranspose — the manual page, but make it make sense

okay so bestie, this is vpTranspose(3) from the Library Functions Manual — yes we're in section 3, the library calls section, the iconique one 🫶

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✨ NAME ✨

vpTranspose — transpose a volume. that's it. that's the whole vibe. 🦋

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✨ SYNOPSIS ✨

#include <volpack.h>

vpResult
vpTranspose(vpc, axis)
    vpContext *vpc;
    int axis;

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✨ ARGUMENTS ✨

• vpc — your VolPack context, the one you got from vpCreateContext. it's the whole world basically 👑
• axis — the axis that should have the smallest stride after transposing. you gotta hand her one of VP_X_AXIS, VP_Y_AXIS or VP_Z_AXIS. no substitutes, she's picky 💅

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✨ DESCRIPTION ✨

so vpTranspose exists to transpose the 3D voxel array, and the whole point is to optimize the memory stride for one particular principal viewing axis. it's giving "let me arrange your data so your renderer stops suffering" 🧚

the intended way to use this — like, the way the authors actually meant it — is:

1. set the viewing transformation
2. call vpGeti with the VP_VIEW_AXIS argument to find the corresponding viewing axis
3. call vpTranspose with that axis

that's the recipe, no cap 🍓

transposing the data changes the arrangement of the data stored in the 3D voxel array. important. the voxel stride state variables get updated to reflect that change, so the viewing transformation does not need to be changed after transposing. you're welcome, you don't have to go back and redo anything 🙈

and if the volume is already transposed for the axis you asked for? she returns immediately without modifying the voxel array. no wasted work, we love an efficient queen ✨

heads up: this function is useful only for rendering large 3D voxel arrays. and it has no affect on the preclassified volume data. like, none. zero. don't come for the preclassified data, she's not involved 😭

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✨ STATE VARIABLES ✨

you can retrieve the relevant variables with these state variable codes (peep vpGeti(3) for the deets):

• VP_VIEW_AXIS
• VP_VOXEL_XSTRIDE
• VP_VOXEL_YSTRIDE
• VP_VOXEL_ZSTRIDE

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✨ ERRORS ✨

the normal return value is VP_OK — that's your slay outcome 💖

but the following error return values are possible, and yes they will absolutely ruin your afternoon:

• VPERROR_BAD_OPTION — the axis argument is invalid. you gave her an axis that isn't real. embarrassing for everyone involved 💀
• VPERROR_BAD_VOLUME — the 3D voxel array is missing or invalid. where is she. WHERE IS SHE 😭
• VPERROR_BAD_VOXEL — the voxel fields are incorrectly specified. the fields, bestie. the fields 🫠

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✨ SEE ALSO ✨

• VolPack(3)
• vpCreateContext(3)

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and that's the page!! this whole thing comes to you courtesy of VolPack — that's the source and the version, right there, no extra date drama attached 💜 go transpose something, main character 🎀