doc/ctsim-appendix.tex

   1 \appendix
   2
   3 \chapter{Simple Graphics Package}\label{appendix}\index{Simple Graphics Package}
   4 \setheader{{\it Appendix \thechapter}}{}{}{\ctsimheadtitle}{}{{\it Appendix \thechapter}}%
   5 \ctsimfooter%
   6
   7 Simple Graphics Package was created in 1980 by Kevin Rosenberg and
   8 is modelled after the hypothetical graphics library described by Foley and van
   9 Dam\cite{FOLEY82}. It is designed to be platform-independent.
  10
  11 \section{Flowchart}
  12
  13 \parbox{11cm}{
  14 \centerline{Master coordinate (MC) level}
  15 \centerline{$\downarrow$}
  16 \centerline{Apply \emph{Current transformation matrix}}
  17 \centerline{$\downarrow$}
  18 \centerline{World coordinate (WC) level}
  19 \centerline{$\downarrow$}
  20 \centerline{Clipping against Window}
  21 \centerline{$\downarrow$}
  22 \centerline{Convert to Normalized device coordinates (NDC)}
  23 \centerline{$\downarrow$}
  24 \centerline{Clipping against Viewport}
  25 \centerline{$\downarrow$}
  26 \centerline{Convert to Physical device coordinates (PDC)}
  27 }
  28
  29 \section{Functions}%
  30
  31 \subsection{Master coordinate functions}
  32 \begin{twocollist}
  33 \twocolitem{\texttt{setWindow(xmin,ymin,xmax,ymax)}}{Set window for world
  34 coordinates}
  35 \twocolitem{\texttt{moveAbs(x,y)}}{Move graphics cursor to absolute position}
  36 \twocolitem{\texttt{moveRel(dx,dy)}}{Move graphics cursor relative to current position}
  37 \twocolitem{\texttt{pointAbs(x,y)}}{Draw point at current position}
  38 \twocolitem{\texttt{pointRel(dx,dy)}}{Draw point relative to current position}
  39 \twocolitem{\texttt{lineAbs(x,y)}}{Draw line from current position to
  40 absolute position}
  41 \twocolitem{\texttt{lineRel(dx,dy)}}{Draw line from current position to position
  42 relative to current position}
  43 \twocolitem{\texttt{markerAbs(x,y)}}{Draw marker at current position}
  44 \twocolitem{\texttt{markerRel(dx,dy)}}{Draw marker relative to current position}
  45 \twocolitem{\texttt{polylineAbs(x[],y[],n)}}{Draw a series of lines to absolute position}
  46 \twocolitem{\texttt{polylineRel(dx[],dy[],n)}}{Draw series of lines relative to current position}
  47 \twocolitem{\texttt{drawString(str)}}{Draw text string at current positon}
  48 \twocolitem{\texttt{drawCircle(r)}}{Draw circle at current positon}
  49 \twocolitem{\texttt{drawArc(r,start,stop)}}{Draw arc with center at current positon}
  50 \twocolitem{\texttt{drawRect(xmin,ymin,xmax,ymax)}}{Draw rectangle}
  51 \end{twocollist}
  52
  53 \subsection{Normalized coordinate functions}%
  54 \begin{twocollist}
  55 \twocolitem{\texttt{Viewport(xmin,ymin,xmax,ymax)}}{Viewport for window
  56 in NDC}
  57 \twocolitem{\texttt{stylus(x,y,beam)}}{Draw a line from current
  58 position if beam = 1, otherwise move stylus to new position}
  59 \twocolitem{\texttt{markerNDC(xndc,yndc)}}{Draw marker at NDC position}
  60 \end{twocollist}
  61
  62 \subsection{Master coordinate to World coordinate transformations}%
  63 These transformation functions operate on the \emph{Current transformation
  64 matrix} (CTM).
  65
  66 \begin{twocollist}
  67 \twocolitem{\texttt{clearCTM()}}{Sets the CTM to an identity matrix}
  68 \twocolitem{\texttt{preTranslate(x,y)}}{Apply translation to CTM}
  69 \twocolitem{\texttt{postTranslate(x,y)}}{Apply translation to CTM}
  70 \twocolitem{\texttt{preScale(x,y)}}{Apply scale to CTM}
  71 \twocolitem{\texttt{postScale(x,y)}}{Apply scale to CTM}
  72 \twocolitem{\texttt{preRotate(angle)}}{Apply rotation to CTM}
  73 \twocolitem{\texttt{postRotate(angle)}}{Apply rotation to CTM}
  74 \twocolitem{\texttt{preShear(x,y)}}{Apply shear to CTM}
  75 \twocolitem{\texttt{postShear(x,y)}}{Apply shear to CTM}
  76 \end{twocollist}
  77
  78 \subsection{Coordinate transformation functions}%
  79 \begin{twocollist}
  80 \twocolitem{\texttt{transformMCtoNDC(\&x,\&y)}}{Convert from master
  81 coordinates to NDC}
  82 \twocolitem{\texttt{transformNDCtoMC(\&x,\&y)}}{Convert from NDC to master
  83 coordinates}
  84 \end{twocollist}
  85
  86 \subsection{State functions}
  87 \begin{twocollist}
  88 \twocolitem{\texttt{eraseWindow()}}{Clears the screen}
  89 \twocolitem{\texttt{setColor(color)}}{Set current pen color}
  90 \twocolitem{\texttt{setLinestyle(style)}}{Set current pen style}
  91 \twocolitem{\texttt{setLinewidth(width)}}{Set current pen width}
  92 \twocolitem{\texttt{setTextColor(foreground, background)}}{Set text colors}
  93 \twocolitem{\texttt{setMarker(type,color)}}{Set marker attibutes}
  94 \twocolitem{\texttt{setRasterOp(rasterOp)}}{Set raster operator}
  95 \end{twocollist}
  96
  97 \section{Coordinate Mapping}
  98
  99 \subsection{Dimensions}
 100 Window (World Coordinates):  $X_{wmin}, X_{wmax}, Y_{wmin}, Y_{wmax}$ \\
 101 Viewport (Normalized Device Coordinates): $X_{vmin}, X_{vmax}, Y_{vmin}, Y_{vmax}$\\
 102 Physical (Physicial Device Coordinates): $X_{pmax}, Y_{pmax}$\\
 103
 104 \subsection{Formulas}
 105 To convert from Master coordinates to World coordinates: \\
 106 \centerline{Apply \emph{current transformation matrix}}
 107
 108 To convert from WC to NDC:\\
 109 \begin{equation}
 110 X_{ndc} = X_{vmin} + (X_{vmax} - X_{vmin})  (X_{wc} - X_{wmin}) / (X_{wmax} - X_{wmin})
 111 \end{equation}
 112 \begin{equation}
 113 Y_{ndc} = Y_{vmin} + (Y_{vmax} - Y_{vmin}) (Y_{wc} - Y_{wmin}) / (Y_{wmax} - Y_{wmin})
 114 \end{equation}
 115
 116 To convert from NDC to PDC:
 117 \begin{equation}
 118      X_{pdc} = X_{ndc} X_{pmax}
 119 \end{equation}
 120 \begin{equation}
 121      Y_{pdc} = X_{ndc} Y_{pmax}
 122 \end{equation}