\chapter{Methods and Design}
-\section{Softare Overview}
-\input{chapters/Process/SoftwareOverview}
-\section{Design Process}
-\input{chapters/Process/DesignProcess}
-\section{Coordinate Systems and Bounds Transformations}
-\input{chapters/Process/Transformations}
-\section{Measurements}
-\input{chapters/Process/Measurements}
+{\bf TODO} Write most of this section. I suspect I will have to be very selective about what to fit in considering the word limit.
+\section{Collaborative Process}
+\begin{itemize}
+ \item Collaborated with David Gow on the design and implementation of the SVG viewer
+ \item Individual work: Applying GMP Rationals (Sam), Quadtree (David)
+ \begin{itemize}
+ \item CPU renderer, SVG parsing, Control Panel, Python Scripts - Sam
+ \item Most of the OpenGL stuff, Scaling/Translating controls - David
+ \item Other parts were worked on by everyone
+ \end{itemize}
+ \item Used git to collaborate \url{https://git.ucc.asn.au}
+ \item Used preprocessor defines to not interfere with each other's code too much
+ \item David used a \verb/goto/ letting the team down
+\end{itemize}
+\section{Structure of Software}
+\begin{itemize}
+ \item CPU and GPU renderer supported
+ \begin{itemize}
+ \item See figure in ``Floating Point Operations on the CPU and GPU''
+ \end{itemize}
+ \item Rendering of Cubic B\'{e}ziers (no antialiasing)
+ \item Partial implementation of shading Paths on CPU (abandoned)
+ \item Ability to move the view around the document with the mouse
+ \item Ability to insert an SVG into the view location
+ \item \verb/typedef/ for number representations
+ \item Ability to control program through scripts or stdio
+ \item Hacky python scripts to produce plots by abusing this
+\end{itemize}
+
+\section{Approaches to Arbitrary Precision}
+\begin{itemize}
+ \item Replace \emph{all} operations with arbitrary precision (ie: Rationals) - Horrendously slow
+ \item Change approach to applying coordinate transform \eqref{view-transformation}
+ \item Apply view transformations directly to objects as the view is transformed, rather than just before rendering
+ \begin{itemize}
+ \item Allows much better precision and range with just regular IEEE-754 floats
+ \item But there is an accumulated rounding error, particularly when zooming out and back in, which is bad
+ \end{itemize}
+ \item As above, but introduce intermediate coordinate system; use the Path elements
+ \begin{itemize}
+ \item Rendering of individual paths is consistent but overall they drift apart
+ \end{itemize}
+ \item As above, but specify Path coordinates with arbitrary precision rationals
+ \begin{itemize}
+ \item Works well, rationals slow down though
+ \end{itemize}
+\end{itemize}
+
+\section{Number Representations Trialed}
+\begin{itemize}
+ \item IEEE-754 single, double, extended
+ \item Custom implementation of Rationals with \verb/int64_t/
+ \begin{itemize}
+ \item Very limited since the integers grow exponentially and overflow
+ \end{itemize}
+ \item Custom implementation of Rationals with custom Arbitrary precision integers
+ \begin{itemize}
+ \item Actually works
+ \item Implementation of division is too slow to be feasible
+ \end{itemize}
+ \item Custom rationals but with GMP arbitrary precision integers
+ \begin{itemize}
+ \item Our implementation of GCD is not feasible
+ \end{itemize}
+ \item Paranoid Numbers; store a operation tree of IEEE-754 floats and simplify the tree wherever \verb/FE_INEXACT/ is \emph{not} raised
+ \begin{itemize}
+ \item This was a really, really, really, bad idea
+ \end{itemize}
+ \item Just use GMP rationals already
+ \begin{itemize}
+ \item Works
+ \end{itemize}
+
+ \item MPFR floats
+ \begin{itemize}
+ \item They work, but they don't truly give arbitrary precision
+ \item Because you have to specify the maximum precision
+ \item However, this can be changed at runtime
+ \item Future work: Trial MPFR floats changing the precision as needed
+ \end{itemize}
+
+\end{itemize}
+
+\section{Libraries Used}
+\begin{itemize}
+ \item SDL2 - Simple Direct media Library
+ \begin{itemize}
+ \item Used for window management and to obtain an OpenGL context
+ \item Also provides BMP handling which is useful
+ \end{itemize}
+ \item Qt4 (optional)
+ \begin{itemize}
+ \item Open source toolkit for Dialog based applications
+ \item We can optionally compile with a Qt4 based control panel
+ \item This is useful for interacting with the document
+ \item Has way more features than we actually use it for
+ \end{itemize}
+ \item OpenGL - Standard API for rendering on GPUs
+ \begin{itemize}
+ \item Using GLSL shaders
+ \item B\'{e}ziers are rendered using a Geometry shader which produces line segments
+ \end{itemize}
+ \item PugiXML - Open source XML parsing library
+ \begin{itemize}
+ \item Used to parse SVGs
+ \end{itemize}
+ \item GNU Multiple Precision (GMP)
+ \begin{itemize}
+ \item Implements arbitrary precision integers, floats, and rationals
+ \item We can use the arbitrary precision integers with a custom rational type
+ \item Or just use the GMP rational type (much better)
+ \item We don't use the floats, because they are hardware dependent
+ \end{itemize}
+ \item MPFR
+ \begin{itemize}
+ \item MPFR is built on GMP but ensures IEEE-754 consistent rounding behaviour
+ \item (Not hardware dependent)
+ \item We can compile with MPFR floats but the precision is currently fixed at compile time
+ \end{itemize}
+\end{itemize}
+
+
+\section{Design of Performance Tests}
+\begin{itemize}
+ \item This is mostly covered in the Results chapter
+ \item Control the program through stdin using a python script
+ \item Results plotted with matplotlib
+\end{itemize}
git.ucc.asn.au / ipdf / sam.git / blobdiff
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