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use std::marker::PhantomData;
use std::mem::size_of_val;
#[derive(Debug)]
pub struct Buffer<Item>
{
buf: gl::types::GLuint,
_pd: PhantomData<Item>,
}
impl<Item> Buffer<Item>
{
pub fn new() -> Self
{
let mut buffer = gl::types::GLuint::default();
unsafe {
gl::CreateBuffers(1, &mut buffer);
};
Self { buf: buffer, _pd: PhantomData }
}
/// Stores items in the currently bound buffer.
pub fn store(&mut self, items: &[Item], usage: Usage)
{
unsafe {
#[allow(clippy::cast_possible_wrap)]
gl::NamedBufferData(
self.buf,
size_of_val(items) as gl::types::GLsizeiptr,
items.as_ptr().cast(),
usage.into_gl(),
);
}
}
pub fn object(&self) -> gl::types::GLuint
{
self.buf
}
/// Does a weak clone of this buffer. The buffer itself is NOT copied in any way this
/// function only copies the internal buffer ID.
///
/// # Safety
/// The returned `Buffer` must not be dropped if another `Buffer` referencing the
/// same buffer ID is used later or if a [`VertexArray`] is used later.
///
/// [`VertexArray`]: crate::opengl::vertex_array::VertexArray
pub unsafe fn clone_weak(&self) -> Self
{
Self { buf: self.buf, _pd: PhantomData }
}
}
impl<Item> Drop for Buffer<Item>
{
fn drop(&mut self)
{
unsafe {
gl::DeleteBuffers(1, &self.buf);
}
}
}
/// 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,
}
}
}
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