CXT105@psuvm.psu.edu (Christopher Tate) (09/02/90)
What is a good, fast, accepted method for rotating bitmaps? Going bit by
bit seems like a terribly inefficient way to do it, but I'm having trouble
coming up with a more "intimate" method that isn't terribly complicated.
Mostly, I just want to be able to rotate text in an offscreen bitmap to
multiples of 90 degree orientations. I'm working in C, so I have access
to inline assembly and all those wonderful bit operators.
Also, rotating bitmaps seems like a much easier task than rotating pixmaps.
Although I don't have to work with pixmaps for the particular project I'm
working on now, I may have to sometime.... Info on this problem would
also be appreciated.
-------
Christopher Tate | "In a fit of perverse brilliance, Carl the
| repairman mistook a room humidifier for a
cxt105@psuvm.psu.edu | mid-size computer, but managed to get it
cxt105@psuvm.bitnet | to connect to the network anyway."mil@mendel.acc.Virginia.EDU (Maria I. Lasaga) (09/03/90)
In article <90244.145341CXT105@psuvm.psu.edu> CXT105@psuvm.psu.edu (Christopher Tate) writes: >What is a good, fast, accepted method for rotating bitmaps? Going bit by >bit seems like a terribly inefficient way to do it, but I'm having trouble >coming up with a more "intimate" method that isn't terribly complicated. > >Mostly, I just want to be able to rotate text in an offscreen bitmap to >multiples of 90 degree orientations. I'm working in C, so I have access >to inline assembly and all those wonderful bit operators. > >Also, rotating bitmaps seems like a much easier task than rotating pixmaps. >Although I don't have to work with pixmaps for the particular project I'm >working on now, I may have to sometime.... Info on this problem would >also be appreciated. > >------- >Christopher Tate | "In a fit of perverse brilliance, Carl the > | repairman mistook a room humidifier for a >cxt105@psuvm.psu.edu | mid-size computer, but managed to get it >cxt105@psuvm.bitnet | to connect to the network anyway." See IEEE: CG&A, May, 1987, p.21-30, for a summary of software and hardware solutions to orthogonal rotations of bitmap images. -------------------------------------------------------------------------- Maria I. Lasaga Dept. of Psychology Gilmer Hall University of Virginia Charlottesville, Virginia 22903 mil@virginia.bitnet --------------------------------------------------------------------------
liberte@yoyodyne.ncsa.uiuc.edu (09/06/90)
Related to the question on rotating bitmaps, I need an algorithm to map a rectangular bitmap to a parallelogram, or more generally, an arbitrary quadralateral. I know it is done in various drawing programs, but how is it done? References appreciated. Dan LaLiberte National Center for Supercomputing Applications liberte@ncsa.uiuc.edu
wlj1@cunixb.cc.columbia.edu (Wayne L Jebian) (09/06/90)
I've missed most of this discussion, unfortunately, but can anyone suggest where I can find a good discussion of mapping planes to 3-d objects (spheres, etc.)? Can anyone share an algorithm with me? I am _not_ a graphics expert. Thanks! -Wayne