Dodger on wrote... | Oh, sorry if what I said was confusing. I'm using this to convert | *textures* for 3D models, not to render the 3d models. | Yes byt the texture generator in povray it is fantastic even if you are only wanting a 2-D texture. This is even talked about in the PovRay manual. This was my point.
| Thus I want to be able to take a texture designed for the latter, bad | mapping of the figure and translate it to fit on the former good | mapping. Each square would be repositioned, scaled, rotated as | necessary, and the trapezoid would be undistorted. Of course, rather | than thinking of them as squares, however, I'd be thinking of each | square/trapezoid as a pair of triangles. For square, ABCD, I'd think | in term of triangles ABC and BCD. But the warping owuld only take | place in 2D, not 3D. | | Thanks fcor the link to xmorph. I'll look closely at that as soon as I | get where I'm going and back online. | I understand what you are saying. However warping or unwarping a square is definateally not the same as a triangle. Warping one triangle to another triagle in 2-D space is a linear operation, that IM can handle with a affine matrix. However warping a square many not be linear. When 4 points are involved the warping becomes trpaziolidal, or a perspective transform. That is the X and Y axis may be scaled differently depending on the other axis. In other words you could have one scaling of the figure at one position and a slightly different scale at another position. Without such a perspecitive transform, four points may not map to four other points. For a proposal for a 'simple' and future 'perspetive matrix' transform additions to IM 'furture proposals'. http://www.cit.gu.edu.au/~anthony/graphics/imagick6/bugs/future/#trapezoid | > > Every quad is simply two tris. Any quad can be warped as tris by | > > warping the tri of the first three points, and then warping the tri of | > > the last three points. Put it that way yes. a quad is just two triangles. In fact two differnet sets of triangles (in most cases). The problem with that is that it is not a smooth transsition between the two triangles. You get a disjoint warp. Sure you can smooth it out, but that is getting very complex and messy compared to a trapeziodial transform. | > Of course you could always use enough triangles to approximate a | > perspective transform with affine transforms. In that case, I suggest | > looking at the xmorph program on sourceforge (xmorph.sourceforge.net). | > It does 2D warping, and you may be able to use IM to convert between | > your source format and TGA, then use morph/xmorph on the TGA files. | > The question now becomes, rather than generate a perspecitive/ trapediodal trensform for four points, we instead implement a general triangular mesh transform, allowing use to then do warps of a picture into perspetive, circular, curves, paper fold overs etc etc etc. This of course would require some means of feeding a triangular mesh patterns into IM, and providing some generators for such meshes as well. Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]> ----------------------------------------------------------------------------- Think of it as 'Evolution in Action'! -- Larry Niven ----------------------------------------------------------------------------- Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/ _______________________________________________ Magick-users mailing list [email protected] http://studio.imagemagick.org/mailman/listinfo/magick-users
