Get the 'spiral()' function right. It wasn't doing the right number o…

…f line segments to give a full 'turn'. TODO: move this function into the library, hopefully a correct version.

dala2.c

@@ -977,16 +977,15 @@ void superellipse(const double x0, const double y0, const double a, const double
 
 void spiral(const double cx, const double cy, const double radius, const double ang, const int n)
 {
-   double theta = ang;
-   double thinc = 2.0 * M_PI / 72.0;
+   double delta = 2.0 * M_PI / 72.0;
    int i;
-   int ptnumber = 72 * n;
+   int npts = 72 * n;
 
    moveto(cx, cy);
 
-   for (i = 0; i < ptnumber; i++) {
-      theta += thinc;
-      const double r = (radius * i) / (double)ptnumber;
+   for (i = 1; i <= npts; i++) {
+      const double theta = ang + (delta * (double)i);
+      const double r = (radius * i) / (double)npts;
       const double x = (r * cos(theta)) + cx;
       const double y = (r * sin(theta)) + cy;
 

dala2c.c

@@ -126,18 +126,17 @@ int main (int argc, char * const argv[])
 
 void spiral (double cx, double cy, double radius, double ang, int n)
 {
-   double theta = ang;
-   double thinc = 2.0 * M_PI / 72.0;
+   double delta = 2.0 * M_PI / 72.0;
    double r;
    int i;
-   int ptnumber = 72 * n;
+   int npts = 72 * n;
    double x, y;
 
    moveto (cx, cy);
 
-   for (i = 0; i < ptnumber; i++) {
-      theta += thinc;
-      r = (radius * i) / (double)ptnumber;
+   for (i = 1; i <= npts; i++) {
+      const double theta = ang + (delta * (double)i);
+      r = (radius * i) / (double)npts;
       x = (r * cos (theta)) + cx;
       y = (r * sin (theta)) + cy;
 

twist.c

@@ -71,7 +71,7 @@ void spiral(const double xc, const double yc, const double r1, const double r2,
    int i;
    const double dr = (r2 - r1) / (72.0 * n);
 
-   for (i = 0; i < (72 * n); i++) {
+   for (i = 0; i <= (72 * n); i++) {
       const double theta = ang + (delta * i);
       const double r = r1 + (dr * i);
       const double x = (r * cos(theta)) + xc;