%!
%
% Date: Tue, 26 Jul 88 21:27:39 EDT
% To: NeWS-makers@brillig.umd.edu
% Subject: Big brother
% From: eagle!icdoc!Ist!jh@ucbvax.Berkeley.EDU  (Jeremy Huxtable)
% 
% Try this out on your NeWS server.....
% 
% eye.ps
%
% Jeremy Huxtable
%
% "Big Brother" implementation in PostScript.
% 
% Date: Sun, 31 Jul 88 04:12:50 EDT
% To: NeWS-makers@brillig.umd.edu
% Subject: smooth motion in Huxtable's eye.ps
% From: icsia!fanty@ucbvax.Berkeley.EDU  (Mark Fanty)
% 
% NeWS animation which erases the old image before drawing the new one
% often has an unpleasant flickering.  I liked Jeremy Huxtable's
% recently posted eye.ps (Re: Big brother) so much I decided to attempt
% a fix for the eyeballs.  My solution uses clipping to avoid erasing
% any part of what will be the new eyeball.
% 
%         Mark Fanty
%         International Computer Science Institute
%         1947 Center Street., Suite 600
%         Berkeley, CA 94704
% 
%         (415) 643-7294
%         fanty@icsi.berkeley.edu
%

% Create an Eyeball class from the Default window class.

/Eyeball DefaultWindow
dictbegin
    /EyeX 0 def                 % Current eyeball position
    /EyeY 0 def
    /MouseEventMgr null def     % Event manager
dictend
classbegin
    /Transform {
	initmatrix initclip
	clippath pathbbox scale pop pop
	.5 .5 translate
    } def

    /ShapeFrameCanvas {
	gsave ParentCanvas setcanvas
	FrameX FrameY translate
	FrameWidth FrameHeight scale
	.5 .5 .5 0 360 arc
        closepath
	FrameCanvas setcanvasshape
	grestore
    } def

    /PaintFrame { } def

    /DrawFrame {
	bordercolor setcolor clippath fill
	0 0 .45 0 360 arc
	backgroundcolor setcolor fill
    } def

    /ShapeClientCanvas { } def

    /CreateClientCanvas { /ClientCanvas FrameCanvas newcanvas def } def

    /PaintClient {
	FrameCanvas setcanvas
	damagepath clipcanvas
	Transform DrawFrame clipcanvas
	EyeX EyeY 0 painteyeball
    } def

    /PaintFocus { } def

    /activate { % create event manager to watch the mouse.
	FrameCanvas setcanvas
	/MouseEventMgr [
	    MouseDragged
	    {
		begin
		    XLocation YLocation 0 painteyeball
		    /EyeX XLocation store
		    /EyeY YLocation store
		    currentdict
		end
		redistributeevent
	    }
	    null % Action
	    null % Canvas
	    eventmgrinterest
	    dup /Exclusive true put
	] forkeventmgr def
    } def

    /painteyeball { % x y colour =>
	setgray
	exch atan /angle exch def
	angle cos .2 mul
	angle sin .2 mul
	2 copy 2 copy
	Transform
        newpath
	gsave
	0 0 .45 0 360 arc clip % avoid border
        newpath
	% clip around new eye before erasing to avoid flicker
	.15 0 360 arc
	.8 0 360 arc eoclip backgroundcolor fillcanvas
        grestore
	.15 0 360 arc fill
    } def

    % /painteyeball { % x y colour =>
	% setgray
	% exch atan /angle exch def
	% angle cos .2 mul
	% angle sin .2 mul
	% Transform
	% .15 0 360 arc fill
    % } def

classend def

% Now actually create a pair of eyes.
/eyeball framebuffer /new Eyeball send def
100 700 16 16 /reshape eyeball send
/map eyeball send
/activate eyeball send
/eyeball framebuffer /new Eyeball send def
145 705 16 16 /reshape eyeball send
/map eyeball send
/activate eyeball send