From 4619444ed11abf715d24f13b1a3a621a899dae91 Mon Sep 17 00:00:00 2001
From: Jared Miller <jared@smell.flowers>
Date: Thu, 12 Feb 2026 21:09:48 -0500
Subject: [PATCH] Cache sorted layer indices on Art

---
 playscii/art.py           | 13 +++++++++++++
 playscii/renderable.py    |  4 +---
 playscii/ui_art_dialog.py |  1 +
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/playscii/art.py b/playscii/art.py
index 9120e98..57bb523 100644
--- a/playscii/art.py
+++ b/playscii/art.py
@@ -141,6 +141,7 @@ class Art:
         self.instances = []
         "List of ArtInstances using us as their source"
         # init frames and layers - ArtFromDisk has its own logic for this
+        self._sorted_layers = None
         self.init_layers()
         self.init_frames()
         # support non-square characters:
@@ -177,6 +178,14 @@ class Art:
         self.layers_visibility = [True]
         self.layer_names = ["Layer 1"]
 
+    def get_sorted_layers(self):
+        "Return layer indices sorted by Z depth, cached until invalidated."
+        if self._sorted_layers is None:
+            self._sorted_layers = tuple(
+                sorted(range(self.layers), key=lambda i: self.layers_z[i])
+            )
+        return self._sorted_layers
+
     def init_frames(self):
         self.frames = 0
         # current frame being edited
@@ -309,6 +318,7 @@ class Art:
         self.layer_names.append(new_name)
         # rebuild geo with added verts for new layer
         self.geo_changed = True
+        self._sorted_layers = None
         # set new layer as active
         if self is self.app.ui.active_art:
             self.app.ui.set_active_layer(self.layers - 1)
@@ -346,6 +356,7 @@ class Art:
         self.layer_names.pop(index)
         self.layers -= 1
         self.geo_changed = True
+        self._sorted_layers = None
         self.mark_all_frames_changed()
         if self.active_layer > self.layers - 1:
             self.app.ui.set_active_layer(self.layers - 1)
@@ -1316,6 +1327,7 @@ class ArtInstance(Art):
         self.renderables = []
         # instances shouldn't have instances; cause user problems if attempted
         self.instances = None
+        self._sorted_layers = None
         self.restore_from_source()
         self.source.instances.append(self)
 
@@ -1339,6 +1351,7 @@ class ArtInstance(Art):
             setattr(self, prop, getattr(self.source, prop))
         # copy lists
         self.layers_z = self.source.layers_z[:]
+        self._sorted_layers = None
         self.layers_visibility = self.source.layers_visibility[:]
         self.layer_names = self.source.layer_names[:]
         self.frame_delays = self.source.frame_delays[:]
diff --git a/playscii/renderable.py b/playscii/renderable.py
index ea17f69..bec00c4 100644
--- a/playscii/renderable.py
+++ b/playscii/renderable.py
@@ -528,9 +528,7 @@ class TileRenderable:
         GL.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA)
         # draw all specified layers if no list given
         if layers is None:
-            # sort layers in Z depth
-            layers = list(range(self.art.layers))
-            layers.sort(key=lambda i: self.art.layers_z[i], reverse=False)
+            layers = self.art.get_sorted_layers()
         # handle a single int param
         elif type(layers) is int:
             layers = [layers]
diff --git a/playscii/ui_art_dialog.py b/playscii/ui_art_dialog.py
index 320b417..7f9df82 100644
--- a/playscii/ui_art_dialog.py
+++ b/playscii/ui_art_dialog.py
@@ -693,6 +693,7 @@ class SetLayerZDialog(UIDialog):
             return
         new_z = float(self.field_texts[0])
         self.ui.active_art.layers_z[self.ui.active_art.active_layer] = new_z
+        self.ui.active_art._sorted_layers = None
         self.ui.active_art.set_unsaved_changes(True)
         self.ui.app.grid.reset()
         self.dismiss()