From 495a2f02f5668712c7e4ebbcb39e7c12080189bd Mon Sep 17 00:00:00 2001
From: jabu <46233424+jabuwu@users.noreply.github.com>
Date: Wed, 13 Sep 2023 05:29:48 -0500
Subject: [PATCH] improve attachment_renderer_object docs and usage (#17)

---
 examples/miniquad.rs |  4 +++-
 src/draw/combined.rs | 20 ++++++++++++++------
 src/draw/simple.rs   | 36 ++++++++++++++++++++++--------------
 3 files changed, 39 insertions(+), 21 deletions(-)

diff --git a/examples/miniquad.rs b/examples/miniquad.rs
index 1e12329..471e952 100644
--- a/examples/miniquad.rs
+++ b/examples/miniquad.rs
@@ -4,7 +4,7 @@
 //!
 //! # Texture Creation & Disposal
 //!
-//! Callbacks must be set to handle texture loading upon loading a [`rusty_spine::Atlas`].
+//! Callbacks must first be set to handle texture loading upon loading a [`rusty_spine::Atlas`].
 //! See [`SpineTexture`].
 //!
 //! # Texture Runtime Settings
@@ -616,6 +616,7 @@ impl EventHandler for Stage {
             bindings.index_buffer.update(ctx, &renderable.indices);
 
             // If there is no attachment (and therefore no texture), skip rendering this renderable
+            // May also be None if a create texture callback was never set.
             let Some(attachment_renderer_object) = renderable.attachment_renderer_object else {
                 continue;
             };
@@ -707,6 +708,7 @@ impl EventHandler for Stage {
 }
 
 fn main() {
+    // These texture callbacks should be set before loading an atlas.
     rusty_spine::extension::set_create_texture_cb(|atlas_page, path| {
         fn convert_filter(filter: AtlasFilter) -> FilterMode {
             match filter {
diff --git a/src/draw/combined.rs b/src/draw/combined.rs
index 462975d..a94db6a 100644
--- a/src/draw/combined.rs
+++ b/src/draw/combined.rs
@@ -118,7 +118,7 @@ impl CombinedDrawer {
                                 unreachable!();
                             },
                             |region_attachment| {
-                                let next_attachment_renderer_object = Some(unsafe {
+                                let next_attachment_renderer_object = unsafe {
                                     region_attachment
                                         .renderer_object()
                                         .get_atlas_region()
@@ -127,13 +127,17 @@ impl CombinedDrawer {
                                         .c_ptr_ref()
                                         .rendererObject
                                         .cast_const()
-                                });
-                                next_attachment_renderer_object
+                                };
+                                if next_attachment_renderer_object.is_null() {
+                                    None
+                                } else {
+                                    Some(next_attachment_renderer_object)
+                                }
                             },
                         )
                     },
                     |mesh_attachment| {
-                        let next_attachment_renderer_object = Some(unsafe {
+                        let next_attachment_renderer_object = unsafe {
                             mesh_attachment
                                 .renderer_object()
                                 .get_atlas_region()
@@ -142,8 +146,12 @@ impl CombinedDrawer {
                                 .c_ptr_ref()
                                 .rendererObject
                                 .cast_const()
-                        });
-                        next_attachment_renderer_object
+                        };
+                        if next_attachment_renderer_object.is_null() {
+                            None
+                        } else {
+                            Some(next_attachment_renderer_object)
+                        }
                     },
                 );
 
diff --git a/src/draw/simple.rs b/src/draw/simple.rs
index ae6099f..5a142ab 100644
--- a/src/draw/simple.rs
+++ b/src/draw/simple.rs
@@ -248,30 +248,38 @@ impl SimpleDrawer {
             let attachment_renderer_object =
                 slot.attachment().and_then(|a| a.as_mesh()).map_or_else(
                     || {
-                        slot.attachment().and_then(|a| a.as_region()).map(
+                        slot.attachment().and_then(|a| a.as_region()).and_then(
                             |region_attachment| unsafe {
-                                region_attachment
+                                let attachment_renderer_object = region_attachment
                                     .renderer_object()
                                     .get_atlas_region()
                                     .unwrap()
                                     .page()
                                     .c_ptr_ref()
                                     .rendererObject
-                                    .cast_const()
+                                    .cast_const();
+                                if attachment_renderer_object.is_null() {
+                                    None
+                                } else {
+                                    Some(attachment_renderer_object)
+                                }
                             },
                         )
                     },
-                    |mesh_attachment| {
-                        Some(unsafe {
-                            mesh_attachment
-                                .renderer_object()
-                                .get_atlas_region()
-                                .unwrap()
-                                .page()
-                                .c_ptr_ref()
-                                .rendererObject
-                                .cast_const()
-                        })
+                    |mesh_attachment| unsafe {
+                        let attachment_renderer_object = mesh_attachment
+                            .renderer_object()
+                            .get_atlas_region()
+                            .unwrap()
+                            .page()
+                            .c_ptr_ref()
+                            .rendererObject
+                            .cast_const();
+                        if attachment_renderer_object.is_null() {
+                            None
+                        } else {
+                            Some(attachment_renderer_object)
+                        }
                     },
                 );