\section{Simple Graphics Package}\index{Simple Graphics Package}%
\subsection{Overview}%
-Simple Graphics Package was creates in 1983 by Kevin Rosenberg and is modelled after the graphics library in Foley and van Dam\cite{FOLEY82}.
+Simple Graphics Package was created in 1980 by Kevin Rosenberg and
+is modelled after the graphics library in Foley and van
+Dam\cite{FOLEY82}.
\begin{verbatim}
+------------------------+
\subsection{Functions}%
-\subsubsection{World Coordinate Level}%
- initgrf2 () Initialize 2 dimensional graphics\\
- termgrf2 () Terminate 2 dimensional graphics\\
- Window (xmin, ymin, xmax, ymax) Set window for world coordinates\\
- Viewport (xmin, ymin, xmax, ymax) Viewport for window in NDC\\
- MoveAbs (x, y) Move graphics cursor\\
- MoveRel (dx, dy)\\
- PointAbs (x, y) Plot point at current position\\
- PointRel (dx, dy)\\
- LineAbs2 (x, y) Draw line from current point to point\\
- LineRel2 (dx, dy)\\
- MarkerAbs2 (x, y) Draw marker at current position\\
- MarkerRel2 (dx, dy)\\
- PolylineAbs (x[], y[], n) Draw a set of lines\\
- PolylineRel (dx[]. dy[]. n)\\
- wc\_to\_ndc (xwc, ywc, xndc, yndc) Convert from world coord to NDC\\
- ndc\_to\_wc (xndc, yndc, xwc, ywc) Convert from NDC to world coord\\
- DrawText (str) Draw text string at current positon\\
+\subsubsection{World Coordinate Level}
+\begin{twocollist}
+\twocolitem{initgrf2}{Initialize 2 dimensional graphics}
+\twocolitem{termgrf2}{Terminate 2 dimensional graphics}
+\twocolitem{setColor(color)}{Set current drawing color}
+\twocolitem{setLinestyle (style)}{Set current line style}
+\twocolitem{setLinewidth (width)}{Set current line width}
+\twocolitem{setTextColor (foreground, background)}{If back=-1,
+then transparent} \twocolitem{setMarker (type, color)}{Set marker
+attibutes}
+\end{twocollist}
- INTERNAL:\\
- calc\_map () Calculate wc to ndc factors\\
- clip(rectangle[4], x1, y1, x2, y2) Clip a line againt rectangle\\
+\subsubsection{State Commands}
+\begin{twocollist}
+\twocolitem{Window(xmin, ymin, xmax, ymax)}{Set window for world
+coordinates} \twocolitem{MoveAbs(x, y)}{Move graphics cursor}
+\twocolitem{MoveRel(dx, dy)}{} \twocolitem{PointAbs (x, y)}{Plot
+point at current position} \twocolitem{PointRel (dx, dy)}{}
+\twocolitem{LineAbs2 (x, y)}{Draw line from current point to
+point} \twocolitem{LineRel2 (dx, dy)}{} \twocolitem{MarkerAbs2 (x,
+y)}{Draw marker at current position} \twocolitem{MarkerRel2 (dx,
+dy)}{} \twocolitem{PolylineAbs (x[], y[], n)}{Draw a set of lines}
+\twocolitem{PolylineRel (dx[], dy[], n)}{}
+\twocolitem{wc\_to\_ndc(xwc, ywc, xndc, yndc)}{Convert from world
+coord to NDC} \twocolitem{ndc\_to\_wc(xndc, yndc, xwc,
+ywc)}{Convert from NDC to world coord} \twocolitem{DrawText
+(str)}{Draw text string at current positon}
+\end{twocollist}
\subsubsection{Normalized Coordinate level}%
- stylus (x, y, beam) Draw a line from current position\\
- setColor (color) Set current drawing color\\
- setLinestyle (style) Set current line style\\
- setLinewidth (width) Set current line width\\
- setTextColor (foreground, background) If back=-1, then transparent \\
+\begin{twocollist}
+\twocolitem{Viewport (xmin, ymin, xmax, ymax)}{Viewport for window
+in NDC} \twocolitem{stylus (x, y, beam)}{Draw a line from current
+position} \twocolitem{markerNDC(xndc, yndc)}{Draw marker at NDC
+position}
+\end{twocollist}
- setMarker (type, color) Set marker attibutes\\
- markerNDC (xndc, yndc) Draw marker at NDC position\\
-\subsection{Coordinate Mapping}%
+\subsection{Coordinate Mapping}
\subsubsection{Mapping from world coordinates to physical device coordinates}%
-Window (World Coordinates): xwmin, xwmax, ywmin, ywmax \\
-Viewport (Normalized Device Coordinates): xvmin, xvmax, yvmin, yvmax\\
-Physical (Physicial Device Coordinates): xpmax, ypmax\\
+Window (World Coordinates): $X_{wmin}, X_{wmax}, Y_{wmin}, Y_{wmax}$ \\
+Viewport (Normalized Device Coordinates): $X_{vmin}, X_{vmax}, Y_{vmin}, Y_{vmax}$\\
+Physical (Physicial Device Coordinates): $X_{pmax}, Y_{pmax}$\\
To convert from WC to NDC:\\
\begin{equation}
- X_{ndc} = X_vmin + (X_wc - X_wmin) / (X_wmax - X_wmin)
+ X_{ndc} = X_{vmin} + (X_{vmax} - X_{vmin}) (X_{wc} - X_{wmin}) / (X_{wmax} - X_{wmin})
\end{equation}
\begin{equation}
- Y_{ndc} = Y_vmin + (Y_wc - Y_wmin) / (Y_wmax - Y_wmin)
+ Y_{ndc} = Y_{vmin} + (Y_{vmax} - Y_{vmin}) (Y_{wc} - Y_{wmin}) / (Y_{wmax} - Y_{wmin})
\end{equation}
+
To convert from NDC to PDC:
\begin{equation}
X_{pdc} = X_{ndc} X_{pmax}
\begin{equation}
Y_{pdc} = X_{ndc} Y_{pmax}
\end{equation}
-
-So, for each device set up the following composite transformation:\\
-\begin{equation}
- x_{pdc} = x_{pmax} (x_{vmin} + (x_{wc} - x_{wmin}) / (x_{wmax} - x_{wmin}))
-\end{equation}
-\begin{equation}
- y_{pdc} = y_{pmax} (y_{vmin} + (y_{wc} - y_{wmin}) / (y_{wmax} - y_{wmin}))
-\end{equation}
-\begin{equation}
- X_{pdc} = X_{pmax} X_{vmin} + ((X_{wc} \- X_{wmin}) X_{pmax})/(X_{wmax} \- X_{wmin}))
-\end{equation}
-\begin{equation}
- X_{pdc} = X_{add} + (X_wc - X_{sub}) X_{fract}
-\end{equation}
projects / ctsim.git / blobdiff