texture "map input" panel and 3d coordinates

I understand textures/materials generally and intuitively understand the “Map To” panel, but I don’t understand the “Map Input” panel.

Of this, the online user guide says “Each Texture has a 3D coordinate (the texture coordinate) as input. The values, passed to the texture as coordinates for each pixel of the rendered image belonging to a given material…”

I don’t really understand what this means. If I understand, a texture is a 2d image. What happens next with these “3d coordinates”? And what is the difference between global and local coordinates and the various vectors mentioned in the user guide on this particular topic?

Thanks for any help. I’ve been randomly playing with this panel, but I’d really like to understand what I’m doing here…

It’s all really simple and makes a lot of sense [yet is still very powerful]

the top set of buttons, orco, uv, object, glob, win, nor ref … determine what the texture coordinates are generated from
UV: uv coordinates
obj: [in the text box goes the name of the object]
glob: global coordinates, texture stays put in space as object moves
orco: original coordinates, texture stays put on object as it deforms and moves
sticky: not very useful, they are per-vertex uv coordinates which cannot be modified. They are created by pressing the make sticky button in the edit buttons iirc
win: window coordinates
nor: surface normal
ref: surface reflection vector

the sets of 3 numeric inputs on the right are for the offset and scaling in each axis of the texture [to rotate the texture you’d probably want to use an obj-mapped texture, which also is easier to animate]

the Flat tube cube and Sphere buttons are from what I can tell only used when mapping images. They define how the image is wrapped around the object [how a 2d object is put on a 3d surface]. The docs cover this part pretty well

hrm, is blender.org and blender3d.org down? [if they weren’t I’d link to the page mentioning the effects of those buttons, with pictures]

the last 12 buttons I think are the coolest.

The top row is for the x axis, the second row for the y axis, and the third row for the z axis. The buttons determine which input axis goes to that axis. So, the default is that the x axis coordinate goes to the x axis as you’d expect. These buttons allow you to flip textures as you’d like.

For example, the default settings do not make for a very interesting result with a normal mapped blend texture. You can map it so the blend is on the front facing the camera with X Y [Null] and on the back, on the edges of a mesh with Z Z [Null]