I got someway stuck translating tutorial-effects-neighbouring-pixels at the end of the first paragraph:
But given a textures original size (WIDTH/HEIGHT) you can compute the distance between two pixels in texture coordinate units. The math is simple: If texture coordinate 0 specifies pixel 0 and texture coordinate 1 specifies pixel WIDTH one pixel has a dimension of 1 / WIDTH. So you can specify the size of a pixel as being:
pixelWidth = 1 / WIDTH
pixelHeight = 1 / HEIGHT
because I can’t get the step from coords to size.
Let’s say we have a texture 400*300.
Talking 'bout WIDTH, we have texcoord 0 pointing to pixel 0 (leftmost) and texcoord 1 indirectly specifying WIDTH (texcoord 1 = pixel number 400, rightmost = WIDTH).
Now, how it happens that a pixel has a dimension? Further, why compute the dimension, the size of a pixel? It’s why it will be rendered in screespace on the mesh? But this has nothing to do with the computation of blur effect itself (I mean: original texture -> blurring texture -> blurred texture on mesh), no?
So, which is the link between “compute distance between two pixels” and “specify the size of a pixel”?
I’ve searched, outside vvvv too, for some hints, didn’t find anything, and still missing logic behind it.
I found the remaining text clear e relatively simple through single steps, but overall is quite vague to me, till I clear out this point.
Thank you very much.