On Jan 27, 4:29 pm, David Fanning <n...@dfanning.com> wrote:
> Well, you can do shapes easily enough just by connecting
> the dots. For example, in AnnotateWindow you can choose
> a pencil cursor and draw whatever shape you like (if you
> have any drawing talent, of course). You just can't get
> ALL the points the cursor crosses over. I don't think
> object graphics will help in this case, either. You will
> have learned them for nothing. :-)
>
Right, you can join the dots... so when IDL plots the line between the
dots, it calculates which pixels need to turn white. How do I get the
coords of all those pixels?
I have come up with a three-step linear interpolation that I do
between each pair of points and it seems to be working (with 2 probs).
here is a snippet:
pro dlines
f_xsize = 300
f_ysize = 300
map = bytarr(f_xsize, f_ysize,2)*0b
FOR line = 0, 1 DO BEGIN
cursor, d1, d2, /down, /device
device, cursor_standard = 32
!mouse.button=0
x1 = 0 > d1 < f_xsize-1
y1 = 0 > d2 < f_ysize-1
WHILE (!MOUSE.button NE 4) DO BEGIN
plots, x1, y1, /device, ps = 3, color = fsc_color((['green',
'red'])[line])
map[x1,y1, line] = 1b
oldx = x1
oldy = y1
CURSOR, X1, Y1, /device,1
x1 = 0 > x1 < f_xsize-1
y1 = 0 > y1 < f_ysize-1
dx = abs(x1-oldx)
dy = abs(y1-oldy)
l = sqrt((dx)^2+(dy)^2)
IF ~keyword_set(nointerpolation) AND l GT sqrt(2) THEN BEGIN
IF dx EQ 0 THEN BEGIN ; if I need to interpolate
a vertical segment
xx = indgen(dy)+min([y1, oldy]) ;new x's
yy = round(interpol([x1, oldx], [y1, oldy], xx))
map[yy,xx, replicate(line, n_elements(xx)) ] = 1b
ENDIF ELSE BEGIN ; all other orientations
xx = indgen(dx)+min([x1, oldx]) ;new x's
yy = round(interpol([y1, oldy], [x1, oldx], xx))
map[xx,yy, replicate(line, n_elements(xx)) ] = 1b
;;need to do this for certain diagonals
IF dy NE 0 THEN BEGIN xx = indgen(dy)+min([y1,
oldy]) ;new x's
yy = round(interpol([x1, oldx], [y1, oldy], xx))
map[yy,xx, replicate(line, n_elements(xx)) ] = 1b
ENDIF
ENDELSE
ENDIF
ENDWHILE
w = where(map[*,*,line] EQ 1b)
a = array_indices(map[*,*,line], w)
device, /cursor_crosshair
ENDFOR
END
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
Problem #1: it is not very pretty, but I could live with that I
suppose. Though I feel there must be a better way.
Problem #2: when you (slowly!) move the mouse out of the left edge of
the window the program crashes because x1= 0>x1<f_xsize-1 sets x1 to
-1!!! And I can't figure that one out :-(
> P.S. Even using the pencil tool in something like Photoshop
> you see that if you move your pencil fast you get a straight
> line, while if you move it slowly you can get a nice even
> bend in the line. I think this is a function of your
> medium (a computer) and not a function of your art skills.
>
Hmm... I am not sure where you're going with the above. I hope the
first part of this reply and the code clarify my issues...
Thanks,
Gianguido
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