[Gzz-commits] gzz/Documentation/Manuscripts/Irregu irregu.tex

[Tuomas J. Lukka]

CVSROOT:        /cvsroot/gzz
Module name:    gzz
Changes by:     Tuomas J. Lukka <address@hidden>        02/11/27 05:57:42

Modified files:
        Documentation/Manuscripts/Irregu: irregu.tex 

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Index: gzz/Documentation/Manuscripts/Irregu/irregu.tex
diff -u gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.66 
gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.67
--- gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.66        Fri Nov 22 
07:33:38 2002
+++ gzz/Documentation/Manuscripts/Irregu/irregu.tex     Wed Nov 27 05:57:42 2002
@@ -53,12 +53,56 @@
 
 \section{Introduction}
 
+\begin{figure}
+\centering
+\fbox{\vbox{\vskip 3in}}
+\caption{
+\label{fig-breakout}
+a) Break out lines, b) a break out section.
+Freehand lines have been long used in engineering drawings
+to indicate that an object extends beyond the shown part.
+}
+\end{figure}
+
+In this article, we apply {\em break lines} or {\em break out section}s
+from technical drawing to viewports.
+Break lines or break out sections (see Fig.~\ref{fig-breakout})
+are freehand lines drawn to indicate
+that an object extends beyond the part drawn in the diagram.
+These lines ``work'' because the implication to the reader
+is that it is {\em not} possible that the wavy line is actually
+the shape of the machine part, it has to be an artifact of the drawing.
+
+Instead of framing a part viewport to the canvas,
+we tear a part of the canvas non-photorealistically, using break lines to 
indicate
+the edges of the tear.
+In the following sections, we first describe related work, then the reasons 
and design issues and
+which features are desirable. Next, we describe a mathematical solution to the
+geometric problem and discuss a hardware-accelerated implementation.
+Finally, we discuss some example applications.
+
+
+\section{Related work}
+
+\subsection{Viewports}
+
 As discussed in \cite{kramer94translucentwindows}, 
 viewports, i.e.~regions of the screen (usually framed), showing part 
 of a larger 2D plane (called {\em canvas} from here on),
 have been used in user interfaces since Sutherland's
 Sketchpad system\cite{XXX}.
 
+This region is usually forced to be rectangular and parallel to the bounding 
rectangle of the canvas.
+(we shall not be concerned with occlusion by other graphical objects: we shall 
only
+concentrate on the basic characteristics of the viewport).
+
+Viewports are used because the computer screen is finite and we need to be able
+to see a part of the canvas in more detail.
+Indeed, the conventional metaphor for representing viewports {\em is} the 
computer screen: 
+a rectangular region of pixels surrounded by a frame.
+The frame is not affected by the motion of the contents of the viewport.
+
+
 % and was brought to the current form by ... 
 % (refs from kramer94translucentwindows)
 %Kay: Flex, Smalltalk?!
@@ -101,8 +145,18 @@
 what we are trying to demonstrate the dominance of rectangular,
 framed viewports.
 Indeed, the only references we found in the literature where
-non-rectangular viewports are actually used are 
\cite{kramer94translucentwindows} and \cite{bier93toolglass}.
-XXX go through carefully, explain here
+non-rectangular viewports are actually used are 
+\cite{bier93toolglass}
+and
+\cite{kramer94translucentwindows}.
+In the toolglass system\cite{bier93toolglass}, 
+a round magnifying glass is used; whether it should
+be called a viewport is debatable: it shows a part of the canvas
+underneath it magnified.
+This is also true for Kramer's work on translucent 
patches\cite{kramer94translucentwindows}:
+there, too, the non-rectangular windows are no viewports but rather complete 
regions, without 
+a separate underlying canvas.
+
 
 ---
 
@@ -124,7 +178,7 @@
 However, in all these cases, the irregular
 shape of the window matches the shape of an actual
 irregular object (clock, shooting hole etc.). 
-The windows are not used as viewports, 
+The irregular windows are not used as viewports, 
 since they always show the whole irregular object,
 not only part of it.
 
@@ -134,17 +188,30 @@
 %              to be an own 2D object, not an irregular window
 %              through which part of the object is seen.
 
-Windowing systems usually non-photorealistic. Clearer, etc.
-However, the understanding of non-photorealism has been developing
-only recently... more photorealism could be distracting... too much
-detail ... focusing user attention. Conveying semantic information:
-unfinishedness... (cite architectural study) 
+\subsection{Non-photorealistic rendering}
+
+Non-photorealistic rendering is a relatively new subfield of 
+computer graphics. 
+The principal ideas are presented by Saito and 
Takahashi\cite{saito90comprehensible}:
+creating images that emulate artistic drawings instead of photographs can
+clarify the images greatly.
+
+Non-photorealistic rendering is able to focus user attention on the relevant 
details
+and also convey semantic mood and semantic information (e.g., ``this is not a 
finished
+design''\cite{architecturalXXX}).
 
-However, the work on non-photorealistic rendering has been concentrated
+The recent work on non-photorealistic rendering has been concentrated
 more on rendering polygonal 3D models in ways which resemble 
 paitings or drawings
 of real-world objects by human artists.
 
+Windowing systems usually non-photorealistic. Of course, this is not originally
+an UI design but a {\em technical} decision; however, 
+Clearer, etc.
+However, the understanding of non-photorealism has been developing
+only recently... 
+
+
 ---
 
 
@@ -183,30 +250,6 @@
 
 % Contribution of this article
 
-\begin{figure}
-\centering
-\fbox{\vbox{\vskip 3in}}
-\caption{
-\label{fig-breakout}
-a) Break out lines, b) a break out section.
-Freehand lines have been long used in engineering drawings
-to indicate that an object extends beyond the shown part.
-}
-\end{figure}
-
-In this article, we apply {\em break lines} or {\em break out section}s
-from technical drawing to viewports.
-Break lines or break out sections (see Fig.~\ref{fig-breakout})
-are freehand lines drawn to indicate
-that an object extends beyond the drawn part.
-
-Instead of framing a part viewport to the canvas,
-we tear a part of the canvas non-photorealistically.
-In the following sections, we first describe the reasons and design issues and
-which features are desirable. Next, we describe a mathematical solution to the
-geometric problem and discuss a hardware-accelerated implementation.
-Finally, we discuss some example applications.
-
 \section{Tearing}
 
 Terms: canvas, tear-out, connected/scattered, envelope, spine of the envelope,
@@ -222,25 +265,15 @@
 In this section, we introduce the use of non-photorealistic rough, torn shapes 
instead 
 of the usual rectangular, clipped and framed viewports.
 
-We shall define viewport as a region of screen, which shows a region
-from a rectangular virtual {\em canvas}.
-This region is usually forced to be rectangular and parallel to the bounding 
rectangle of the canvas.
-(we shall not be concerned with occlusion by other graphical objects: we shall 
only
-concentrate on the basic characteristics of the viewport).
-
-Viewports are used because the computer screen is finite and we need to be able
-to see a part of the canvas in more detail.
-Indeed, the conventional metaphor for representing viewports {\em is} the 
computer screen: 
-a rectangular region of pixels surrounded by a frame.
-The frame is not affected by the motion of the contents of the viewport.
-
-Tearing, as we propose it, is a different metaphor for viewports.
+Tearing, as we propose it, is a new metaphor for viewports.
 Instead of showing a virtual computer screen showing a part of the canvas,
 we show a piece torn off the canvas. 
 
-In the following subsections, we first discuss why tearing is desirable (and 
different
-from the usual viewports), then the details of the design and finally the 
algorithmic side. The next section concentrates
-on implementing these algorithms at an interactive frame rate.
+In the following subsections, we first discuss why tearing is desirable and how
+it differs from the usual viewports, 
+then the details of the design and finally an algorithm with the required 
properties.
+% The next section concentrates
+% on implementing these algorithms at an interactive frame rate.
 
 \subsection{Rationale ``Why?''}
 
@@ -323,6 +356,8 @@
 
 \subsection{Algorithm ``How?''} 
 
+XXX IDEAL: Displacement of edge curve by 2D offset "texture"!?
+
 In this subsection, we formulate the design criteria of the preceding section 
mathematically
 and discuss
 a simple algorithm for a shape with the desired properties.
@@ -623,7 +658,7 @@
 Increasing the border width scaling exponent from 0 makes the
 border width less consistent with sloped offset.
 
-\subsection{Future work: NV30}
+\subsection{Future work: NV30 and R300}
 
 XXX