From bf1fc240119779e8667afc4d4f228e50f1ed6ef0 Mon Sep 17 00:00:00 2001
From: Stephen Seo <seo.disparate@gmail.com>
Date: Sun, 17 Mar 2024 18:46:01 +0900
Subject: [PATCH] Refactor: Split init code into function

Previous implementation originally had "init_vulkan" initialization
struct creation seperated into a different function, but was merged into
"init_vulkan" due to memory issues. More specifically, the struct
creation function used pointers to local variables that were not used
until the function went out of scope, causing the local variables to be
cleaned up and leaving the pointers in the "struct info" struct invalid
when they were actually used in a `ffi::Vk...` call.

This refactoring ensures that pointers to variables created in the
mentioned function does not become invalid when the function ends by
stored the pointees in `Pin<Box<...>>` and returning them with the
"struct info" struct at the end of the mentioned function.
---
 src/main.rs | 42 +++++++++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index bd6aa8c..a389730 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,6 +3,8 @@ mod math3d;
 
 use std::collections::HashSet;
 use std::ffi::{c_void, CStr, CString};
+use std::ops::Deref;
+use std::pin::Pin;
 
 use math3d::Vertex;
 
@@ -949,19 +951,8 @@ impl VulkanApp {
         let shader_stages: [ffi::VkPipelineShaderStageCreateInfo; 2] =
             [vert_shader_stage_info, frag_shader_stage_info];
 
-        let mut vertex_input_info: ffi::VkPipelineVertexInputStateCreateInfo =
-            unsafe { std::mem::zeroed() };
-        vertex_input_info.sType =
-            ffi::VkStructureType_VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
-
-        let bind_desc = Vertex::get_binding_description();
-        let attr_descs = Vertex::get_attribute_descriptions();
-
-        vertex_input_info.vertexBindingDescriptionCount = 1;
-        vertex_input_info.vertexAttributeDescriptionCount = attr_descs.len() as u32;
-
-        vertex_input_info.pVertexBindingDescriptions = std::ptr::addr_of!(bind_desc);
-        vertex_input_info.pVertexAttributeDescriptions = attr_descs.as_ptr();
+        let (vertex_input_info, _bind_desc, _attr_descs) =
+            Self::create_vertex_input_state_info_struct()?;
 
         let mut input_assembly: ffi::VkPipelineInputAssemblyStateCreateInfo =
             unsafe { std::mem::zeroed() };
@@ -1729,6 +1720,31 @@ impl VulkanApp {
 
         Err(String::from("Failed to find suitable memory type!"))
     }
+
+    fn create_vertex_input_state_info_struct() -> Result<
+        (
+            ffi::VkPipelineVertexInputStateCreateInfo,
+            Pin<Box<ffi::VkVertexInputBindingDescription>>,
+            Pin<Box<[ffi::VkVertexInputAttributeDescription; 2]>>,
+        ),
+        String,
+    > {
+        let mut vertex_input_info: ffi::VkPipelineVertexInputStateCreateInfo =
+            unsafe { std::mem::zeroed() };
+        vertex_input_info.sType =
+            ffi::VkStructureType_VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
+
+        let bind_desc = Box::pin(Vertex::get_binding_description());
+        let attr_descs = Box::pin(Vertex::get_attribute_descriptions());
+
+        vertex_input_info.vertexBindingDescriptionCount = 1;
+        vertex_input_info.vertexAttributeDescriptionCount = attr_descs.len() as u32;
+
+        vertex_input_info.pVertexBindingDescriptions = bind_desc.deref();
+        vertex_input_info.pVertexAttributeDescriptions = attr_descs.as_ptr();
+
+        Ok((vertex_input_info, bind_desc, attr_descs))
+    }
 }
 
 impl Drop for VulkanApp {