dashed_plotter: use rotational direction while closing

spec/086_stroke_dash_close_multiple_join.zig

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: 0BSD
+//   Copyright © 2024-2026 Chris Marchesi
+
+//! Case: Renders a closed dashed path that traverses multiple corners on the
+//! close. This tests that direction is retained on the close and the correct
+//! caps are applied on the correct contours.
+const Io = @import("std").Io;
+const mem = @import("std").mem;
+
+const z2d = @import("z2d");
+
+pub const filename = "086_stroke_dash_close_multiple_join";
+
+pub fn render(io: Io, alloc: mem.Allocator, aa_mode: z2d.options.AntiAliasMode) !z2d.Surface {
+    const width = 300;
+    const height = 300;
+    var sfc = try z2d.Surface.init(.image_surface_rgb, alloc, width, height);
+
+    var context = z2d.Context.init(io, alloc, &sfc);
+    defer context.deinit();
+    context.setSourceToPixel(.{ .rgb = .{ .r = 0xFF, .g = 0xFF, .b = 0xFF } });
+    context.setAntiAliasingMode(aa_mode);
+    context.setDashes(&.{ 90, 30 });
+    context.setDashOffset(60);
+    context.setLineWidth(6);
+
+    try context.moveTo(50, 150);
+    try context.lineTo(150, 250);
+    try context.lineTo(250, 50);
+    try context.lineTo(50, 100);
+    try context.closePath();
+
+    try context.stroke();
+
+    return sfc;
+}

spec/main_bench.zig

@@ -100,6 +100,7 @@ const _082_stroke_hairline_clip = @import("082_stroke_hairline_clip.zig");
 const _083_star_simplify_offset = @import("083_star_simplify_offset.zig");
 const _084_offset_ghostty_conformance = @import("084_offset_ghostty_conformance.zig");
 const _085_deja_sans_ignore_invalid_points = @import("085_deja_sans_ignore_invalid_points.zig");
+const _086_stroke_dash_close_multiple_join = @import("086_stroke_dash_close_multiple_join.zig");
 
 //////////////////////////////////////////////////////////////////////////////
 
@@ -222,6 +223,7 @@ pub fn main() !void {
     try addPathBenchmark(&bench, _083_star_simplify_offset);
     try addPathBenchmark(&bench, _084_offset_ghostty_conformance);
     try addPathBenchmark(&bench, _085_deja_sans_ignore_invalid_points);
+    try addPathBenchmark(&bench, _086_stroke_dash_close_multiple_join);
 
     var threaded: Io.Threaded = .init_single_threaded;
     const io = threaded.io();

spec/main_spec.zig

@@ -99,6 +99,7 @@ const _082_stroke_hairline_clip = @import("082_stroke_hairline_clip.zig");
 const _083_star_simplify_offset = @import("083_star_simplify_offset.zig");
 const _084_offset_ghostty_conformance = @import("084_offset_ghostty_conformance.zig");
 const _085_deja_sans_ignore_invalid_points = @import("085_deja_sans_ignore_invalid_points.zig");
+const _086_stroke_dash_close_multiple_join = @import("086_stroke_dash_close_multiple_join.zig");
 
 //////////////////////////////////////////////////////////////////////////////
 
@@ -195,6 +196,7 @@ pub fn main() !void {
     try pathExportRun(io, alloc, _083_star_simplify_offset);
     try pathExportRun(io, alloc, _084_offset_ghostty_conformance);
     try pathExportRun(io, alloc, _085_deja_sans_ignore_invalid_points);
+    try pathExportRun(io, alloc, _086_stroke_dash_close_multiple_join);
 }
 
 //////////////////////////////////////////////////////////////////////////////
@@ -539,6 +541,10 @@ test "085_deja_sans_ignore_invalid_points" {
     try pathTestRun(testing.io, testing.allocator, _085_deja_sans_ignore_invalid_points);
 }
 
+test "086_stroke_dash_close_multiple_join" {
+    try pathTestRun(testing.io, testing.allocator, _086_stroke_dash_close_multiple_join);
+}
+
 //////////////////////////////////////////////////////////////////////////////
 
 fn compositorExportRun(io: Io, alloc: mem.Allocator, subject: anytype) !void {

src/internal/tess/dashed_plotter.zig

@@ -580,6 +580,8 @@ const Plotter = struct {
             // We need to replace the initial polygon with the outer due to the
             // direction of the concat happened in.
             self.initial_polygon.on.outer = self.outer;
+            // Retain clockwise direction from existing polygon
+            self.initial_polygon.on.clockwise_ = self.clockwise_;
 
             // Our first cap points are based entirely off of the plotter state
             // (not the initial state).