[Plplot-cvs] SF.net SVN: plplot:[11842] trunk

[<and...@us...>]

Revision: 11842
          http://plplot.svn.sourceforge.net/plplot/?rev=11842&view=rev
Author:   andrewross
Date:     2011-08-03 12:45:46 +0000 (Wed, 03 Aug 2011)

Log Message:
-----------
Update plarc to use the rotate option to plot ellipses which have the major axis rotated relative to the X-axis.

Also work around bug with filled ellipses which caused crash.

Modified Paths:
--------------
    trunk/doc/docbook/src/api.xml
    trunk/src/plarc.c

Modified: trunk/doc/docbook/src/api.xml
===================================================================
--- trunk/doc/docbook/src/api.xml	2011-08-03 02:19:05 UTC (rev 11841)
+++ trunk/doc/docbook/src/api.xml	2011-08-03 12:45:46 UTC (rev 11842)
@@ -362,6 +362,7 @@
 	  <paramdef><parameter>b</parameter></paramdef>
 	  <paramdef><parameter>angle1</parameter></paramdef>
 	  <paramdef><parameter>angle2</parameter></paramdef>
+	  <paramdef><parameter>rotate</parameter></paramdef>
 	  <paramdef><parameter>fill</parameter></paramdef>
 	</funcprototype>
       </funcsynopsis>
@@ -429,7 +430,7 @@
 	</term>
 	<listitem>
 	  <para>
-	    Starting angle of the arc.
+	    Starting angle of the arc relative to the semimajor axis.
 	  </para>
 	</listitem>
       </varlistentry>
@@ -440,12 +441,23 @@
 	</term>
 	<listitem>
 	  <para>
-	    Ending angle of the arc.
+	    Ending angle of the arc relative to the semimajor axis.
 	  </para>
 	</listitem>
       </varlistentry>
       <varlistentry>
 	<term>
+	  <parameter>rotate</parameter>
+	  (<literal>PLFLT</literal>, input)
+	</term>
+	<listitem>
+	  <para>
+	    Angle of the semimajor axis relative to the X-axis.
+	  </para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term>
 	  <parameter>fill</parameter>
 	  (<literal>PLBOOL</literal>, input)
 	</term>
@@ -462,7 +474,7 @@
       <itemizedlist>
 	<listitem>
 	  <para>
-	    General: <function>plarc(x, y, a, b, angle1, angle2, fill)</function>
+	    General: <function>plarc(x, y, a, b, angle1, angle2, rotate, fill)</function>
 	  </para>
 	</listitem>
       </itemizedlist>

Modified: trunk/src/plarc.c
===================================================================
--- trunk/src/plarc.c	2011-08-03 02:19:05 UTC (rev 11841)
+++ trunk/src/plarc.c	2011-08-03 12:45:46 UTC (rev 11842)
@@ -21,12 +21,9 @@
 
 #include "plplotP.h"
 
-#define CIRCLE_SEGMENTS    ( PL_MAXPOLY - 1 )
+#define CIRCLE_SEGMENTS    ( PL_MAXPOLY - 2 )
 #define DEG_TO_RAD( x )                    ( ( x ) * M_PI / 180.0 )
 
-#define PLARC_POINT_X( x, a, b, theta )    ( ( x ) + ( ( a ) * cos( theta ) ) )
-#define PLARC_POINT_Y( y, a, b, theta )    ( ( y ) + ( ( b ) * sin( theta ) ) )
-
 //--------------------------------------------------------------------------
 // plarc_approx : Plot an approximated arc with a series of lines
 //
@@ -40,12 +37,17 @@
     PLFLT theta0, theta_step, theta, d_angle;
     PLINT segments;
     PLFLT xs[CIRCLE_SEGMENTS + 1], ys[CIRCLE_SEGMENTS + 1];
+    PLFLT cphi,sphi,ctheta,stheta;
 
     // The difference between the start and end angles
     d_angle = DEG_TO_RAD( angle2 - angle1 );
     if ( fabs( d_angle ) > M_PI * 2.0 )
         d_angle = M_PI * 2.0;
 
+    // Calculate cosine and sine of angle of major axis wrt the x axis
+    cphi = cos(DEG_TO_RAD(rotate));
+    sphi = sin(DEG_TO_RAD(rotate));
+
     // The number of line segments used to approximate the arc
     segments = fabs( d_angle ) / ( 2.0 * M_PI ) * CIRCLE_SEGMENTS;
     // Always use at least 2 arc points, otherwise fills will break.
@@ -61,8 +63,10 @@
     for ( i = 0; i < segments; i++ )
     {
         theta = theta0 + theta_step * (PLFLT) i;
-        xs[i] = PLARC_POINT_X( x, a, b, theta );
-        ys[i] = PLARC_POINT_Y( y, a, b, theta );
+        ctheta = cos(theta);
+        stheta = sin(theta);
+        xs[i] = x + a*ctheta*cphi - b*stheta*sphi;
+        ys[i] = y + a*ctheta*sphi + b*stheta*cphi;
     }
 
     if ( fill )


This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site.