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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.2 Final//FR"><!-- Converted with LaTeX2HTML 95.1 (Fri Jan 20 1995) --><!-- by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds --><!-- Modified Simulog 03/97 --><HTML><HEAD><TITLE>3.1 Masks and windows</TITLE><LINK REL=STYLESHEET TYPE="text/css" HREF="./Modulef.css" TITLE="Modulef CSS"><meta name="description" value="3.1 Masks and windows"><meta name="keywords" value="Guide6"><meta name="resource-type" value="document"><meta name="distribution" value="global"></HEAD><BODY BGCOLOR="#FFFFFF"><P> <IMG SRC="../icons/smallmod.gif" WIDTH=211 HEIGHT=50 ALIGN=BOTTOM ALT="Modulef"><A NAME=tex2html1367 HREF="node75.html"><IMG BORDER=0 ALIGN=BOTTOM SRC="../icons/previous_motif.gif" ALT="previous"></A><A NAME=tex2html1373 HREF="node75.html"><IMG BORDER=0 ALIGN=BOTTOM SRC="../icons/up_motif.gif" ALT="up"></A><A NAME=tex2html1375 HREF="node77.html"><IMG BORDER=0 ALIGN=BOTTOM SRC="../icons/next_motif.gif" ALT="next"></A><A NAME=tex2html1377 HREF="node2.html"><IMG BORDER=0 ALIGN=BOTTOM SRC="../icons/contents_motif.gif" ALT="contents"></A><A HREF="../Guide6-18/node76.html"><IMG BORDER=0 SRC="../icons/zoom18.gif" ALIGN=BOTTOM ALT="[BIG]"></A><A HREF="../Guide6-14/node76.html"><IMG BORDER=0 SRC="../icons/zoom14.gif" ALIGN=BOTTOM ALT="[Normal]"></A><A HREF="../Guide6-10/node76.html"><IMG BORDER=0 SRC="../icons/zoom10.gif" ALIGN=BOTTOM ALT="[small]"></A><BR><B> Next: </B> <A NAME=tex2html1376 HREF="node77.html">3.2 Graphics instructions: 2D</A><B>Up: </B> <A NAME=tex2html1374 HREF="node75.html">3 Creating a 2D image</A><B> Prev: </B> <A NAME=tex2html1368 HREF="node75.html">3 Creating a 2D image</A><B><A HREF="node2.html" >Contents</A></B><HR SIZE=3 WIDTH="75%"><H1><A NAME=SECTION05310000000000000000>3.1 Masks and windows</A></H1><P><P><P>The independence of FORTRAN 3D with respect to the type of terminal used wasmentioned earlier. We also talked about the vitual screen on which the object is constructed before producing the image.In this section we deal with the coordinates of this screen using a unitary systemchosen by the user (Angstr鰉, centimeter, kilometer, light-year!...) with respect to the dimensions of the real object. This is the MASK.<P>If we wish the entire object to be visualized, all the points must be inside themask<A NAME=3048> </A>. If the mask is too large, the object will appear small, andif the dimensions of the object are bigger that those of the mask, the entire object willnot be seen. Thus, by playing with the coordinate system and the object's units, we eliminate the notion of screen coordinates advantageously.<P><UL><LI><PRE> SUBROUTINE MASQU2(XMIN, XMAX, YMIN, YMAX) REAL XMIN, XMAX, YMIN, YMAX</PRE><P>This subroutine defines a<A NAME=3050> </A> rectangular mask whose lower left corner is the point (XMIN, YMIN)and the upper right corner is the point (XMAX, YMAX).This mask is, by default, equal to the frame defined on the visualization surface. Only the parts of the object falling inside this mask are retained.<P></UL><P> zoom1.psfig:471Initial plotzoom2.psfig:471bZoom by changing the mask<P><P>It is necessary, secondly, to define a frame on the visualization surfacewhich will contain the image inside the mask. For a plane object, this frame is definedusing the following subroutines:<P><UL><LI><P><PRE> SUBROUTINE FENTR2(XMIN, XMAX, YMIN, YMAX) REAL XMIN, XMAX, YMIN, YMAX</PRE><P>defines a<A NAME=3059> </A> frame on<A NAME=3060> </A> the visualization surface whose lower left corner is the point (XMIN, YMIN) and the upper right corner is the point (XMAX, YMAX). These coordinatesare expressed in centimeters.<P><LI><P><PRE> SUBROUTINE RFENTR(PXMIN, PXMAX, PYMIN, PYMAX) REAL PXMIN, PXMAX, PYMIN, PYMAX</PRE><P>defines a<A NAME=3061> </A> frame on the visualization surface whose lower left corner is the point (PXMIN, PYMIN) and the upper right corner is the point (PXMAX, PYMAX). These coordinatesare expressed as a percentage of the real screen.<P></UL><P>For certain particular applications, it could be advantageous not to take the clipping defined by MASQU2 into account. It is possible to govern this indicator by using the following subroutines:<P><UL><LI><P><PRE> SUBROUTINE CLIP(FLAG) LOGICAL FLAG</PRE><P>suppress<A NAME=3064> </A> the clipping<A NAME=3065> </A> defined by MASQU2 if FLAG equals .FALSE.<P><LI><P><PRE> SUBROUTINE CLIPHD(FLAG) LOGICAL FLAG</PRE><P>hardware clipping, i.e. clipping<A NAME=3066> </A> in the <A NAME=3067> </A> window (instead of in the mask).<P></UL><P><P><P><HR SIZE=3 WIDTH="75%"><IMG SRC="../icons/smallmod.gif" WIDTH=211 HEIGHT=50 ALIGN=BOTTOM ALT="Modulef"><A NAME=tex2html1367 HREF="node75.html"><IMG BORDER=0 ALIGN=BOTTOM SRC="../icons/previous_motif.gif" ALT="previous"></A><A NAME=tex2html1373 HREF="node75.html"><IMG BORDER=0 ALIGN=BOTTOM SRC="../icons/up_motif.gif" ALT="up"></A><A NAME=tex2html1375 HREF="node77.html"><IMG BORDER=0 ALIGN=BOTTOM SRC="../icons/next_motif.gif" ALT="next"></A><A NAME=tex2html1377 HREF="node2.html"><IMG BORDER=0 ALIGN=BOTTOM SRC="../icons/contents_motif.gif" ALT="contents"></A><A HREF="../Guide6-18/node76.html"><IMG BORDER=0 SRC="../icons/zoom18.gif" ALIGN=BOTTOM ALT="[BIG]"></A><A HREF="../Guide6-14/node76.html"><IMG BORDER=0 SRC="../icons/zoom14.gif" ALIGN=BOTTOM ALT="[Normal]"></A><A HREF="../Guide6-10/node76.html"><IMG BORDER=0 SRC="../icons/zoom10.gif" ALIGN=BOTTOM ALT="[small]"></A><BR><B> Next: </B> <A NAME=tex2html1376 HREF="node77.html">3.2 Graphics instructions: 2D</A><B>Up: </B> <A NAME=tex2html1374 HREF="node75.html">3 Creating a 2D image</A><B> Prev: </B> <A NAME=tex2html1368 HREF="node75.html">3 Creating a 2D image</A><B><A HREF="node2.html" >Contents</A></B><BR> <HR><P><ADDRESS></ADDRESS></BODY></HTML>⌨️ 快捷键说明
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