| [opengtl-commits] [686] specify hints |
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Revision: 686
Author: cyrille
Date: 2009-03-26 10:42:45 +0100 (Thu, 26 Mar 2009)
Log Message:
-----------
specify hints
Modified Paths:
--------------
trunk/OpenGTL/OpenShiva/doc/specification/ShivaSpec.tex
Modified: trunk/OpenGTL/OpenShiva/doc/specification/ShivaSpec.tex
===================================================================
--- trunk/OpenGTL/OpenShiva/doc/specification/ShivaSpec.tex 2009-03-25 16:26:19 UTC (rev 685)
+++ trunk/OpenGTL/OpenShiva/doc/specification/ShivaSpec.tex 2009-03-26 09:42:45 UTC (rev 686)
@@ -674,6 +674,59 @@
\part{Standard libray}
+\section{Constants}
+
+\section{Hints}
+Hints are special constants that are available to the Kernel writters (but not
+in libraries), they are called hints since they just provide an approximate
+information, since Kernels are expected to operate on an infinite plane, images
+sizes should just be used to provide a reasonnable scaling, and bounding to the
+user.
+
+\begin{tabular}{|c|c|l|}
+\hline
+Constant name & Type & Description \\
+\hline
+\verb|IMAGE_WIDTH| & \verb|float| & hint of the width of the image \\
+\hline
+\verb|IMAGE_HEIGHT| & \verb|float| & hind of the height of the image \\
+\hline
+\verb|IMAGE_SIZE| & \verb|float2| & vector containing the width and height
+of the image \\
+\hline
+\end{tabular}
+
+A typical use case of those hints is to control the center of an effect:
+
+\begin{lstlisting}
+<
+ parameters: <
+ xcenter: <
+ label: "X center";
+ type: float;
+ minValue: 0;
+ maxValue: 1;
+ defaultValue: 0.5;
+ >;
+ ycenter: <
+ label: "Y center";
+ type: float;
+ minValue: 0;
+ maxValue: 1;
+ defaultValue: 0.5;
+ >;
+>;
+kernel MyKernel
+{
+ const float2 center = { IMAGE_WIDTH * xcenter,
+ IMAGE_HEIGHT * ycenter };
+ void evaluatePixel(output pixel result)
+ {
+ ...
+ }
+}
+\end{lstlisting}
+
\section{Vector functions}
\paragraph{distance}
\paragraph{dot}