X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=moebius2.git;a=blobdiff_plain;f=primer.c;h=76939a6356b9911dc59e29913603cf8af5ee671b;hp=a21dded6765a45618439bbca9ef16de71f7c51cd;hb=9e8860ae32184285e451568d39df79baf7f44aff;hpb=2e8e765ae894f9921fa97db2f21915662f162224

diff --git a/primer.c b/primer.c
index a21dded..76939a6 100644
--- a/primer.c
+++ b/primer.c
@@ -8,21 +8,31 @@
 #include "mgraph.h"
 
 int main(int argc, const char **argv) {
-  int v, k;
+  static const int prec= DBL_DIG+2;
+  int vi;
   
-  if (argc>1) { fputs("no args please\n",stderr); exit(8); }
+  if (argc!=1) { fputs("need no args\n",stderr); exit(8); }
 
-  printf("print %d, %d, %d, %d, %d\n", DIM, N, X, Y, D3);
-  
-  FOR_VERTEX(v) {
-    int x= v & XMASK; /* distance along strip */
-    int y= v >> YSHIFT; /* distance across strip */
-    double u= y * 1.0 / (Y-1);
-    double v= x * M_PI / (X-1); /* SGT's u runs 0..pi along the strip */
-    K printf("print %c%c(%.*g,%.*g)\n",
-	     "+-+"[k],
-	     "xyz"[k],
-	     DBL_DIG+2,u, DBL_DIG+2,v);
+  printf("%d %d %d %d %d\n%%-%d.%dg\n",
+	 X*Y, N, X, Y, D3,
+	 prec+5,prec);
+
+  FOR_VERTEX(vi, INNER) {
+    int x= vi & XMASK; /* distance along strip */
+    int y= vi >> YSHIFT; /* distance across strip */
+    double u= y * 1.0 / (Y-1); /* SGT's u runs 0..1 across the strip */
+
+    /* SGT's v runs 0..pi along the strip, where the join is at 0==pi.
+     * So that corresponds to 0..X (since 0==X in our scheme).
+     * Vertices with odd y coordinate are halfway to the next x coordinate.
+     */
+    double v= (x*2 + (y&1)) * 1.0 / (X*2);
+    v += 0.5;
+    v *= M_PI;
+
+    printf("%-*.*g %-*.*g # %03x %2d %2d\n",
+	   prec+5,prec,u, prec+5,prec,v,
+	   vi, x, y);
   }
   flushoutput();
   return 0;