| Essentially, it is a mean
that was developped to determine where to place, on an object, all the
pixels of an image that we want to use as a texture. We can say to Blender:
"This vertice will be associated with this pixel and this other vertice
with that other pixel... Since there are usually much more pixels in the
image you intent to use than there are vertices in the model, the placement
of the pixels in between vertices is figured out by Blender. That process
is called interpolation.
This page and the next illustrate the fundamentals of how it all works and introduces to the actual technique to get it done by Blender.
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Let's use this tiny 8 pixels by 8 pixels image. |
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Oups, sorry... ;)
Here, enlarged 16 times. |
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So.
Make a plane. [shift+a, add > mesh > plane] |
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In the 3D window, go into 'face select
mode'.
[with the object selected by a right mouse click, press FKEY] This is the mode you must be in for any uvmapping job. |
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Split the 3D window in two.
[Coming from the 3D window, bring the pointer on the small bar between the 3D window and the button window. Click with the right mouse button. Choose 'Split Area'. Place the light gray bar that appeared where you want the separation to occur and click with the left mouse button to set everything in place. ] |
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Change one of the two views to an
image window.
[Shift+F10] |
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Load the tiny image into the image
window.
[Click on the 'Load' button for a sight with thumbnails or the small button just to the right for a text only search (much faster)] |
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With the pointer in the 3D window, press AKEY to select the only face that plane has. [AKEY will toggle between selecting every face and deselecting them all.] A selected face has a dotted line all around it. |
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Just to be on the safe side, press UKEY and choose 'Standard 1/1'. This is a mode of projection for the individual faces ; '1/1' means simply that the whole image will be assigned to each selectec face, one time per face ; '1/2' means that only one quarter (half the width and half the height) will be used ; '1/4' only one sixteenth. Do some experiments of your own sometime . |
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The OpenGL representation can't even
make it out.
['Textured mode' accessed by alt+z] |
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At this stage, if we want to be able to see the uvmapped surface in the renderer, we must check 'TexFace' in the material window [F5]. |
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But that doesn't fool the renderer.
The plane has only four vertices[one at each corner]. Nevertheless, the rest of the pixels is almost perfectly positionned in between those reference points : that's interpolation. Blender computed where the green, the blue, the red pixel... should go based on what was known of (1) the position of the vertices [touched up in yellow here]on the plane and (2) the positions of the pixels in the image. |