shithub: puzzles

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ref: 22417efad6173417e414bee532a6dcd20324e87d
parent: 6f75879e9fe7cb5dc72c9229d1772e31e4f5c77b
author: Simon Tatham <[email protected]>
date: Tue Mar 28 16:29:45 EDT 2023 

Hats tiling: make hat-test draw each hat in one go.

By introducing a second callback between the client of hat.c and the
maybe_report_hat function, I enable the test main() to provide a
different version of that callback, so that instead of enumerating
each kite, it can directly generate a Postscript path per actual hat.
This should make it more useful to people wanting to generate hat
patterns for any other purpose.

The internal callback gets more details than the external one; in
particular, it receives a HatCoords, so that it can colour hats based
on their position in the hierarchical structure.


--- a/hat.c
+++ b/hat.c
@@ -959,9 +959,14 @@
  * kites inside the rectangle, so its kite #0 will certainly be caught
  * by this iteration.)
  */
+
+typedef void (*internal_hat_callback_fn)(void *ctx, Kite kite0, HatCoords *hc,
+                                         int *coords);
+
 static void maybe_report_hat(int w, int h, Kite kite, HatCoords *hc,
-                             hat_tile_callback_fn cb, void *cbctx)
+                             internal_hat_callback_fn cb, void *cbctx)
 {
+    Kite kite0;
     Point vertices[14];
     size_t i, j;
     bool reversed = false;
@@ -970,6 +975,7 @@
     /* Only iterate from kite #0 of a hat */
     if (hc->c[0].index != 0)
         return;
+    kite0 = kite;
 
     /*
      * Identify reflected hats: they are always hat #3 of an H
@@ -1032,9 +1038,19 @@
         coords[2*i+1] = y;
     }
 
-    cb(cbctx, 14, coords);
+    cb(cbctx, kite0, hc, coords);
 }
 
+struct internal_ctx {
+    hat_tile_callback_fn external_cb;
+    void *external_cbctx;
+};
+static void report_hat(void *vctx, Kite kite0, HatCoords *hc, int *coords)
+{
+    struct internal_ctx *ctx = (struct internal_ctx *)vctx;
+    ctx->external_cb(ctx->external_cbctx, 14, coords);
+}
+
 /*
  * Generate a hat tiling from a previously generated set of parameters.
  */
@@ -1045,7 +1061,11 @@
     HatCoords *coords[KE_NKEEP];
     KiteEnum s[1];
     size_t i;
+    struct internal_ctx report_hat_ctx[1];
 
+    report_hat_ctx->external_cb = cb;
+    report_hat_ctx->external_cbctx = cbctx;
+
     init_coords_params(ctx, hp);
     for (i = 0; i < lenof(coords); i++)
         coords[i] = NULL;
@@ -1052,13 +1072,15 @@
 
     first_kite(s, w, h);
     coords[s->curr_index] = initial_coords(ctx);
-    maybe_report_hat(w, h, *s->curr, coords[s->curr_index], cb, cbctx);
+    maybe_report_hat(w, h, *s->curr, coords[s->curr_index],
+                     report_hat, report_hat_ctx);
 
     while (next_kite(s)) {
         hc_free(coords[s->curr_index]);
         coords[s->curr_index] = step_coords(
             ctx, coords[s->last_index], s->last_step);
-        maybe_report_hat(w, h, *s->curr, coords[s->curr_index], cb, cbctx);
+        maybe_report_hat(w, h, *s->curr, coords[s->curr_index],
+                         report_hat, report_hat_ctx);
     }
 
     cleanup_coords(ctx);
@@ -1216,12 +1238,6 @@
     float x, y;
 } pspoint;
 
-static inline pspoint pscoords(Point p)
-{
-    pspoint q = { p.x + p.y / 2.0F, p.y * sqrt(0.75) };
-    return q;
-}
-
 typedef struct psbbox {
     bool started;
     pspoint bl, tr;
@@ -1256,84 +1272,46 @@
            ox + scale * bbox->tr.x + 20, oy + scale * bbox->tr.y + 20);
 
     printf("%f %f translate %f dup scale\n", ox, oy, scale);
-    printf("%f setlinewidth\n", 0.1);
-    printf("/thick { %f setlinewidth } def\n", 0.7);
+    printf("%f setlinewidth\n", scale * 0.03);
     printf("0 setgray 1 setlinejoin 1 setlinecap\n");
 }
 
-static void bbox_add_kite(Kite k, psbbox *bbox)
+static void bbox_add_hat(void *vctx, Kite kite0, HatCoords *hc, int *coords)
 {
-    pspoint p[4];
+    psbbox *bbox = (psbbox *)vctx;
+    pspoint p;
     size_t i;
 
-    p[0] = pscoords(k.centre);
-    p[1] = pscoords(k.left);
-    p[2] = pscoords(k.outer);
-    p[3] = pscoords(k.right);
-
-    for (i = 0; i < 4; i++)
-        psbbox_add(bbox, p[i]);
-}
-
-static void fill_kite(Kite k, HatCoords *hc)
-{
-    pspoint p[4];
-    size_t i;
-
-    p[0] = pscoords(k.centre);
-    p[1] = pscoords(k.left);
-    p[2] = pscoords(k.outer);
-    p[3] = pscoords(k.right);
-
-    printf("newpath");
-    for (i = 0; i < 4; i++)
-        printf(" %f %f %s", p[i].x, p[i].y, i ? "lineto" : "moveto");
-    printf(" closepath gsave");
-    if (hc) {
-        const char *colour = "0 setgray";
-        if (hc->c[2].type == TT_H) {
-            colour = (hc->c[1].index == 3 ? "0 0.5 0.8 setrgbcolor" :
-                      "0.6 0.8 1 setrgbcolor");
-        } else if (hc->c[2].type == TT_F) {
-            colour = "0.7 setgray";
-        } else {
-            colour = "1 setgray";
-        }
-        printf(" %s fill grestore\n", colour);
+    for (i = 0; i < 14; i++) {
+        p.x = coords[2*i] * 1.5;
+        p.y = coords[2*i+1] * sqrt(0.75);
+        psbbox_add(bbox, p);
     }
 }
 
-static void stroke_kite(Kite k, HatCoords *hc)
+static void draw_hat(void *vctx, Kite kite0, HatCoords *hc, int *coords)
 {
-    pspoint p[4];
+    pspoint p;
     size_t i;
+    const char *colour;
 
-    p[0] = pscoords(k.centre);
-    p[1] = pscoords(k.left);
-    p[2] = pscoords(k.outer);
-    p[3] = pscoords(k.right);
-
     printf("newpath");
-    for (i = 0; i < 4; i++)
-        printf(" %f %f %s", p[i].x, p[i].y, i ? "lineto" : "moveto");
-    printf(" closepath");
-    printf(" stroke\n");
-
-    if (hc->c[2].type == TT_H && hc->c[1].index == 3) {
-        pspoint t = p[1]; p[1] = p[3]; p[3] = t;
+    for (i = 0; i < 14; i++) {
+        p.x = coords[2*i] * 1.5;
+        p.y = coords[2*i+1] * sqrt(0.75);
+        printf(" %f %f %s", p.x, p.y, i ? "lineto" : "moveto");
     }
-    #define LINE(a,b) printf("gsave newpath %f %f moveto %f %f lineto thick " \
-            "stroke grestore\n", p[a].x, p[a].y, p[b].x, p[b].y)
-    switch (hc->c[0].index) {
-      case 0: LINE(1, 2); LINE(2, 3); LINE(3, 0); break;
-      case 1: LINE(0, 1); break;
-      case 2: LINE(0, 1); break;
-      case 3: LINE(2, 3); LINE(3, 0); break;
-      case 4: LINE(0, 1); LINE(1, 2); break;
-      case 6: LINE(1, 2); LINE(2, 3); break;
-      case 7: LINE(1, 2); LINE(2, 3); LINE(3, 0); break;
+    printf(" closepath gsave");
+    if (hc->c[2].type == TT_H) {
+        colour = (hc->c[1].index == 3 ? "0 0.5 0.8 setrgbcolor" :
+                  "0.6 0.8 1 setrgbcolor");
+    } else if (hc->c[2].type == TT_F) {
+        colour = "0.7 setgray";
+    } else {
+        colour = "1 setgray";
     }
-    #undef LINE
+    printf(" %s fill grestore", colour);
+    printf(" stroke\n");
 }
 
 static void trailer(void)
@@ -1366,12 +1344,14 @@
 
     first_kite(s, w, h);
     coords[s->curr_index] = initial_coords(ctx);
-    bbox_add_kite(*s->curr, bbox);
+    maybe_report_hat(w, h, *s->curr, coords[s->curr_index],
+                     bbox_add_hat, bbox);
     while (next_kite(s)) {
         hc_free(coords[s->curr_index]);
         coords[s->curr_index] = step_coords(
             ctx, coords[s->last_index], s->last_step);
-        bbox_add_kite(*s->curr, bbox);
+        maybe_report_hat(w, h, *s->curr, coords[s->curr_index],
+                         bbox_add_hat, bbox);
     }
     for (i = 0; i < lenof(coords); i++) {
         hc_free(coords[i]);
@@ -1382,26 +1362,14 @@
 
     first_kite(s, w, h);
     coords[s->curr_index] = initial_coords(ctx);
-    fill_kite(*s->curr, coords[s->curr_index]);
+    maybe_report_hat(w, h, *s->curr, coords[s->curr_index],
+                     draw_hat, NULL);
     while (next_kite(s)) {
         hc_free(coords[s->curr_index]);
         coords[s->curr_index] = step_coords(
             ctx, coords[s->last_index], s->last_step);
-        fill_kite(*s->curr, coords[s->curr_index]);
-    }
-    for (i = 0; i < lenof(coords); i++) {
-        hc_free(coords[i]);
-        coords[i] = NULL;
-    }
-
-    first_kite(s, w, h);
-    coords[s->curr_index] = initial_coords(ctx);
-    stroke_kite(*s->curr, coords[s->curr_index]);
-    while (next_kite(s)) {
-        hc_free(coords[s->curr_index]);
-        coords[s->curr_index] = step_coords(
-            ctx, coords[s->last_index], s->last_step);
-        stroke_kite(*s->curr, coords[s->curr_index]);
+        maybe_report_hat(w, h, *s->curr, coords[s->curr_index],
+                         draw_hat, NULL);
     }
     for (i = 0; i < lenof(coords); i++) {
         hc_free(coords[i]);