From 25b5ca97c5e5597570360c37d7452662e0118a00 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Fri, 13 Oct 2023 22:34:23 +0200
Subject: refactor(engine): make vertex buffer wrapper hold single buffer

---
 engine/src/renderer/vertex_buffer.rs | 77 ++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 engine/src/renderer/vertex_buffer.rs

(limited to 'engine/src/renderer/vertex_buffer.rs')

diff --git a/engine/src/renderer/vertex_buffer.rs b/engine/src/renderer/vertex_buffer.rs
new file mode 100644
index 0000000..27ed705
--- /dev/null
+++ b/engine/src/renderer/vertex_buffer.rs
@@ -0,0 +1,77 @@
+use std::mem::size_of_val;
+
+use crate::vertex::Vertex;
+
+#[derive(Debug)]
+pub struct VertexBuffer
+{
+    buffer: gl::types::GLuint,
+}
+
+impl VertexBuffer
+{
+    pub fn new() -> Self
+    {
+        let mut buffer = gl::types::GLuint::default();
+
+        unsafe {
+            gl::GenBuffers(1, &mut buffer);
+        };
+
+        Self { buffer }
+    }
+
+    pub fn store(&self, vertices: &[Vertex], usage: BufferUsage)
+    {
+        unsafe {
+            gl::BindBuffer(gl::ARRAY_BUFFER, self.buffer);
+        }
+
+        unsafe {
+            #[allow(clippy::cast_possible_wrap)]
+            gl::BufferData(
+                gl::ARRAY_BUFFER,
+                size_of_val(vertices) as gl::types::GLsizeiptr,
+                vertices.as_ptr().cast(),
+                usage.into_gl(),
+            );
+        }
+    }
+}
+
+impl Drop for VertexBuffer
+{
+    fn drop(&mut self)
+    {
+        #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)]
+        unsafe {
+            gl::DeleteBuffers(1, &self.buffer);
+        }
+    }
+}
+
+#[derive(Debug)]
+#[allow(dead_code)]
+pub enum BufferUsage
+{
+    /// The buffer data is set only once and used by the GPU at most a few times.
+    Stream,
+
+    /// The buffer data is set only once and used many times.
+    Static,
+
+    /// The buffer data is changed a lot and used many times.
+    Dynamic,
+}
+
+impl BufferUsage
+{
+    fn into_gl(self) -> gl::types::GLenum
+    {
+        match self {
+            Self::Stream => gl::STREAM_DRAW,
+            Self::Static => gl::STATIC_DRAW,
+            Self::Dynamic => gl::DYNAMIC_DRAW,
+        }
+    }
+}
-- 
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