refactor(engine): rename vertex buffer to buffer & make generic

1 files changed, 94 insertions, 0 deletions

diff --git a/engine/src/opengl/buffer.rs b/engine/src/opengl/buffer.rs
new file mode 100644
index 0000000..34514fd
--- /dev/null
+++ b/engine/src/opengl/buffer.rs
@@ -0,0 +1,94 @@
+use std::marker::PhantomData;
+use std::mem::size_of_val;
+
+use crate::opengl::currently_bound::CurrentlyBound;
+
+#[derive(Debug)]
+pub struct Buffer<Item>
+{
+    buffer: gl::types::GLuint,
+    _item_pd: PhantomData<Item>,
+}
+
+impl<Item> Buffer<Item>
+{
+    pub fn new() -> Self
+    {
+        let mut buffer = gl::types::GLuint::default();
+
+        unsafe {
+            gl::GenBuffers(1, &mut buffer);
+        };
+
+        Self {
+            buffer,
+            _item_pd: PhantomData,
+        }
+    }
+
+    #[allow(clippy::inline_always)]
+    #[inline(always)]
+    pub fn bind(&self, cb: impl FnOnce(CurrentlyBound<'_, Self>))
+    {
+        unsafe {
+            gl::BindBuffer(gl::ARRAY_BUFFER, self.buffer);
+        }
+
+        // SAFETY: The buffer object is bound above
+        let currently_bound = unsafe { CurrentlyBound::new() };
+
+        cb(currently_bound);
+    }
+
+    /// Stores items in the currently bound buffer.
+    pub fn store(_currently_bound: &CurrentlyBound<Self>, items: &[Item], usage: Usage)
+    {
+        unsafe {
+            #[allow(clippy::cast_possible_wrap)]
+            gl::BufferData(
+                gl::ARRAY_BUFFER,
+                size_of_val(items) as gl::types::GLsizeiptr,
+                items.as_ptr().cast(),
+                usage.into_gl(),
+            );
+        }
+    }
+}
+
+impl<Item> Drop for Buffer<Item>
+{
+    fn drop(&mut self)
+    {
+        #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)]
+        unsafe {
+            gl::DeleteBuffers(1, &self.buffer);
+        }
+    }
+}
+
+/// Buffer usage.
+#[derive(Debug)]
+#[allow(dead_code)]
+pub enum Usage
+{
+    /// 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 Usage
+{
+    fn into_gl(self) -> gl::types::GLenum
+    {
+        match self {
+            Self::Stream => gl::STREAM_DRAW,
+            Self::Static => gl::STATIC_DRAW,
+            Self::Dynamic => gl::DYNAMIC_DRAW,
+        }
+    }
+}