From 2face3a43d3cb841501ac6004446162fde447449 Mon Sep 17 00:00:00 2001
From: Jeremy Collins <jeremy.collins@beetlebug.org>
Date: Mon, 13 Jul 2026 01:45:45 +0000
Subject: [PATCH] =?UTF-8?q?fix(bake):=20store=20complex=20linestyle=20runs?=
 =?UTF-8?q?=20=E2=80=94=20the=20baker=20never=20wrote=20them?=
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The bake surface's vtable CLAIMED, in a comment, to store complex runs
un-tessellated so replay could re-walk the period at the display's scale:

    // Bake path: store complex runs un-tessellated (no size_scale set — bake is
    // native; replay re-walks the period display-scaled).

...but .store_complex_run was never set on the vtable. So
canStoreComplexRun() returned false, drawComplexLine tessellated the
period at bake time at size_scale = 1, and no tile ever carried an
ls_style — the replay path that re-walks them has been dead code.

The bricks then scale with the display at render time while their SPACING
stays frozen at 1x, so on a HiDPI display (size_scale ~3) the symbols swell
into each other and a caution/restricted boundary reads as a smashed-up
sawtooth instead of spaced marks.

Wire storeComplexRun on the bake surface, writing the clipped run with its
style id, phase (arc0), colour and width — exactly what replay.zig already
reads. A rebaked Boston cell now carries CTNARE51/ENTRES51/NAVARE51 runs,
and the brick count falls as size_scale rises (74 -> 40 -> 32), i.e. the
spacing finally scales with the bricks.

REQUIRES A REBAKE: the period lives in the tiles.
---
 src/scene/scene.zig | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/scene/scene.zig b/src/scene/scene.zig
index 07c1f91..047d416 100644
--- a/src/scene/scene.zig
+++ b/src/scene/scene.zig
@@ -471,6 +471,7 @@ pub const TileSurface = struct {
         .endScene = endScene,
         // Bake path: store complex runs un-tessellated (no size_scale set — bake is
         // native; replay re-walks the period display-scaled).
+        .store_complex_run = storeComplexRun,
     };
 
     pub fn init(a: Allocator, format: TileFormat) TileSurface {
@@ -599,6 +600,29 @@ pub const TileSurface = struct {
         try s.pointsL().append(s.a, .{ .geom_type = .point, .parts = parts, .properties = props.items });
     }
 
+    /// BAKE: store one clipped complex-linestyle run UN-TESSELLATED, tagged with its style id
+    /// and its phase (arc0), so replay can re-walk the period at the DISPLAY's size_scale.
+    ///
+    /// Without this the baker falls through to drawComplexRun and freezes the period at
+    /// size_scale = 1. The bricks then scale with the display at render time while their
+    /// SPACING does not, so on a HiDPI display (size_scale ~3) the symbols swell into each
+    /// other and the linestyle reads as a smashed-up sawtooth. The whole point of storing the
+    /// run is that spacing and brick size scale TOGETHER, and the baked tile stays
+    /// display-independent — replay.zig has always known how to read this; only the baker
+    /// never wrote it.
+    fn storeComplexRun(ctx: *anyopaque, ls_id: []const u8, color: rs.ColorToken, width_px: f64, arc0: f64, run: []const rs.TilePoint) anyerror!void {
+        const s = sp(ctx);
+        var props = std.ArrayList(mvt.Prop).empty;
+        try props.append(s.a, .{ .key = "ls_style", .value = .{ .string = ls_id } });
+        try props.append(s.a, .{ .key = "ls_arc0", .value = .{ .double = arc0 } });
+        try props.append(s.a, .{ .key = "color_token", .value = .{ .string = color } });
+        try props.append(s.a, .{ .key = "width_px", .value = .{ .double = width_px } });
+        try appendMeta(s.a, &props, s.cur);
+        const parts = try s.a.alloc([]const mvt.Point, 1);
+        parts[0] = run;
+        try s.linesL().append(s.a, .{ .geom_type = .linestring, .parts = parts, .properties = props.items });
+    }
+
     fn drawSounding(ctx: *anyopaque, depth_m: f64, swept: bool, low_acc: bool, at: rs.TilePoint) anyerror!void {
         const s = sp(ctx);
         var props = std.ArrayList(mvt.Prop).empty;