implement Arc() for plot5 and hpgl (smith diagram)

ChangeLog

@@ -1,3 +1,8 @@
+2010-08-02  Robert Larice
+ * src/frontend/hpgl.c ,
+ * src/frontend/plotting/plot5.c :
+    implement Arc() for plot5 and hpgl (smith diagram)
+
 2010-08-01  Holger Vogt
  * autogen.sh: update for adms
  

src/frontend/hpgl.c

@@ -226,23 +226,16 @@ int GL_Arc(
 int x0, int y0, int r,
 double theta, double delta_theta)
 {
-/*
-    double x1, y1;
-    double angle1, angle2;
-
-    while (theta1 >= theta2)
-        theta2 += 2 * M_PI;
-
-    angle1 = (double) (RAD_TO_DEG * theta1);
-    angle2 = (double) (RAD_TO_DEG * theta2);
-    x1 = (double) x0 + r * cos(theta1);
-    y1 = (double) y0 + r * sin(theta1);
-
-    fprintf(plotfile, "%lf %lf moveto ", x1+(double)xoff, y1+(double)yoff);
-    fprintf(plotfile, "%d %d %d %lf %lf arc\n", x0+xoff, y0+yoff, r,
-        angle1, angle2);
-    fprintf(plotfile, "stroke\n");
-  */
+    int  x1, y1, angle;
+
+    x1 = x0 + r * cos(theta);
+    y1 = y0 + r * sin(theta);
+
+    angle = RAD_TO_DEG * delta_theta;
+
+    fprintf(plotfile, "PU;PA %d , %d;", jgmult*(x1+xoff+XTADJ), jgmult*(y1+yoff+YTADJ));
+    fprintf(plotfile, "PD;AA %d , %d, %d;", jgmult*(x0+xoff+XTADJ), jgmult*(y0+yoff+YTADJ), angle);
+
     DEVDEP(currentgraph).linecount = 0;
 
     return 0;

src/frontend/plotting/plot5.c

@@ -114,10 +114,49 @@ Plt5_DrawLine(int x1, int y1, int x2, int y2)
     return 0;
 }
 
-/* ARGSUSED */ /* until some code gets written */
 int
-Plt5_Arc(int x0, int y0, int radius, double theta, double delta_theta)
+Plt5_Arc(int xc, int yc, int radius, double theta, double delta_theta)
 {
+    int x0,y0,x1,y1;
+
+    if(delta_theta < 0) {
+        theta += delta_theta;
+        delta_theta = -delta_theta;
+    }
+
+    if((2*M_PI - delta_theta)*radius < 0.5) {
+
+       putc('c', plotfile);
+       putsi(xc);
+       putsi(yc);
+       putsi(radius);
+
+       return 0;
+    }
+
+    while(delta_theta*radius > 0.5) {
+
+        double delta_phi = M_PI/2;
+
+        if(delta_phi > delta_theta)
+            delta_phi = delta_theta;
+
+        x0 = xc + (radius * cos(theta));
+        y0 = yc + (radius * sin(theta));
+        x1 = xc + (radius * cos(theta + delta_phi));
+        y1 = yc + (radius * sin(theta + delta_phi));
+
+        putc('a', plotfile);
+        putsi(xc);
+        putsi(yc);
+        putsi(x0);
+        putsi(y0);
+        putsi(x1);
+        putsi(y1);
+
+        delta_theta -= delta_phi;
+        theta       += delta_phi;
+    }
 
     return 0;
 }