From 7ed1ba8766e968f9b860c95c9640a32aee85b030 Mon Sep 17 00:00:00 2001
From: Brian Schwind <brianmschwind@gmail.com>
Date: Sun, 21 Jan 2024 19:15:08 +0900
Subject: [PATCH] Toggle hidden-line drawing with the X key in the viewer app
 (#162)

---
 crates/viewer/src/edge_drawer.rs | 29 +++++++++++++++++++----------
 crates/viewer/src/main.rs        |  8 +++++++-
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/crates/viewer/src/edge_drawer.rs b/crates/viewer/src/edge_drawer.rs
index 7d328bbd..51f7c496 100644
--- a/crates/viewer/src/edge_drawer.rs
+++ b/crates/viewer/src/edge_drawer.rs
@@ -29,6 +29,7 @@ pub struct EdgeDrawer {
     bind_groups: BindGroups,
     screen_width: u32,
     screen_height: u32,
+    draw_back_edges: bool,
 }
 
 impl EdgeDrawer {
@@ -61,6 +62,7 @@ impl EdgeDrawer {
             bind_groups,
             screen_width,
             screen_height,
+            draw_back_edges: false,
         }
     }
 
@@ -69,6 +71,10 @@ impl EdgeDrawer {
         self.screen_height = screen_height;
     }
 
+    pub fn toggle_back_edge_drawing(&mut self) {
+        self.draw_back_edges = !self.draw_back_edges;
+    }
+
     #[allow(clippy::too_many_arguments)]
     pub fn draw(
         &self,
@@ -125,19 +131,22 @@ impl EdgeDrawer {
                 timestamp_writes: None,
             });
 
-            // Render dashed line strips
-            render_pass.set_pipeline(&self.dashed_line_strip_pipeline);
             render_pass.set_vertex_buffer(0, self.buffers.round_strip_geometry.slice(..));
             render_pass.set_vertex_buffer(1, rendered_line.vertex_buf.slice(..));
-            render_pass.set_bind_group(0, &self.bind_groups.dashed_vertex_uniform, &[]);
-
-            let mut offset = 0usize;
-            let vertex_count = self.buffers.round_strip_geometry_len as u32;
 
-            for line_strip_size in &rendered_line.line_sizes {
-                let range = (offset as u32)..(offset + line_strip_size - 1) as u32;
-                offset += line_strip_size;
-                render_pass.draw(0..vertex_count, range);
+            // Render dashed line strips
+            if self.draw_back_edges {
+                render_pass.set_pipeline(&self.dashed_line_strip_pipeline);
+                render_pass.set_bind_group(0, &self.bind_groups.dashed_vertex_uniform, &[]);
+
+                let mut offset = 0usize;
+                let vertex_count = self.buffers.round_strip_geometry_len as u32;
+
+                for line_strip_size in &rendered_line.line_sizes {
+                    let range = (offset as u32)..(offset + line_strip_size - 1) as u32;
+                    offset += line_strip_size;
+                    render_pass.draw(0..vertex_count, range);
+                }
             }
 
             // Render solid line strips
diff --git a/crates/viewer/src/main.rs b/crates/viewer/src/main.rs
index f09565b7..aff88373 100644
--- a/crates/viewer/src/main.rs
+++ b/crates/viewer/src/main.rs
@@ -290,12 +290,18 @@ impl GameApp for ViewerApp {
                 self.camera.zoom(-zoom_delta);
             },
             WindowEvent::KeyboardInput {
-                event: KeyEvent { physical_key: PhysicalKey::Code(key_code), .. },
+                event:
+                    KeyEvent {
+                        physical_key: PhysicalKey::Code(key_code),
+                        state: ElementState::Pressed,
+                        ..
+                    },
                 ..
             } => match key_code {
                 KeyCode::Escape => window_target.exit(),
                 KeyCode::KeyP => self.camera.use_perspective(),
                 KeyCode::KeyO => self.camera.use_orthographic(),
+                KeyCode::KeyX => self.line_drawer.toggle_back_edge_drawing(),
                 _ => {},
             },
             _ => {},