From e61e15770ec679fa68118f069ab3c8bdfab510a6 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Thu, 20 Apr 2023 11:06:52 -0400
Subject: [PATCH] Deduplicate vertices for model rendering

---
 src/app/data.rs    | 13 ++++++++++---
 src/app/structs.rs | 22 ++++++++++++++++++++++
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/src/app/data.rs b/src/app/data.rs
index cfc866f..4787193 100644
--- a/src/app/data.rs
+++ b/src/app/data.rs
@@ -8,7 +8,6 @@ use ::std::collections::HashMap;
 use ::std::collections::HashSet;
 use ::std::ffi::CStr;
 use ::std::fs::File;
-use ::std::hash::{Hash, Hasher};
 use ::std::io::BufReader;
 use ::std::os::raw::c_void;
 use ::std::ptr::copy_nonoverlapping as memcpy;
@@ -926,6 +925,8 @@ impl AppData {
             |_| Ok(Default::default()),
         )?;
 
+        let mut unique_vertices = HashMap::new();
+
         for model in &models {
             for index in &model.mesh.indices {
                 let pos_offset = (3 * index) as usize;
@@ -944,8 +945,14 @@ impl AppData {
                     ),
                 );
 
-                self.vertices.push(vertex);
-                self.indices.push(self.indices.len() as u32);
+                if let Some(index) = unique_vertices.get(&vertex) {
+                    self.indices.push(*index as u32);
+                } else {
+                    let index = self.vertices.len();
+                    unique_vertices.insert(vertex, index);
+                    self.vertices.push(vertex);
+                    self.indices.push(index as u32);
+                }
             }
         }
 
diff --git a/src/app/structs.rs b/src/app/structs.rs
index 4125466..cf0bcd3 100644
--- a/src/app/structs.rs
+++ b/src/app/structs.rs
@@ -1,6 +1,7 @@
 use ::anyhow::{anyhow, Result};
 use ::log::*;
 use ::nalgebra_glm as glm;
+use ::std::hash::{Hash, Hasher};
 use ::std::mem::size_of;
 use ::thiserror::Error;
 use ::vulkanalia::prelude::v1_0::*;
@@ -145,6 +146,27 @@ impl Vertex {
     }
 }
 
+impl PartialEq for Vertex {
+    fn eq(&self, other: &Self) -> bool {
+        self.pos == other.pos && self.color == other.color && self.tex_coord == other.tex_coord
+    }
+}
+
+impl Eq for Vertex {}
+
+impl Hash for Vertex {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.pos[0].to_bits().hash(state);
+        self.pos[1].to_bits().hash(state);
+        self.pos[2].to_bits().hash(state);
+        self.color[0].to_bits().hash(state);
+        self.color[1].to_bits().hash(state);
+        self.color[2].to_bits().hash(state);
+        self.tex_coord[0].to_bits().hash(state);
+        self.tex_coord[1].to_bits().hash(state);
+    }
+}
+
 // ----------------------------------------------------------------------------
 // Resource Descriptors
 // ----------------------------------------------------------------------------