feat(opengl-bindings): add Buffer store_at_byte_offset fn

1 files changed, 48 insertions, 0 deletions

diff --git a/opengl-bindings/src/buffer.rs b/opengl-bindings/src/buffer.rs
index 3bb6c48..66ab719 100644
--- a/opengl-bindings/src/buffer.rs
+++ b/opengl-bindings/src/buffer.rs
@@ -87,6 +87,47 @@ impl<Item: ReprC> Buffer<Item>
         Ok(())
     }
 
+    /// Stores items in this buffer, starting at a byte offset.
+    ///
+    /// # Errors
+    /// Returns `Err` if the total size (in bytes) is too large.
+    pub fn store_at_byte_offset(
+        &self,
+        current_context: &CurrentContextWithFns<'_>,
+        byte_offset: usize,
+        items: &[Item],
+        // usage: Usage,
+    ) -> Result<(), Error>
+    {
+        let total_size = size_of_val(items);
+
+        let byte_offset: crate::sys::types::GLintptr =
+            byte_offset
+                .try_into()
+                .map_err(|_| Error::ByteOffsetTooLarge {
+                    byte_offset,
+                    max_byte_offset: crate::sys::types::GLintptr::MAX as usize,
+                })?;
+
+        let total_size: crate::sys::types::GLsizeiptr =
+            total_size.try_into().map_err(|_| Error::SizeTooLarge {
+                size: total_size,
+                max_size: crate::sys::types::GLsizeiptr::MAX as usize,
+            })?;
+
+        unsafe {
+            current_context.fns().NamedBufferSubData(
+                self.buf,
+                byte_offset,
+                total_size,
+                items.as_ptr().cast(),
+                // usage.into_gl(),
+            );
+        }
+
+        Ok(())
+    }
+
     /// Maps the values in the `values` slice into `Item`s which is stored into this
     /// buffer.
     ///
@@ -203,4 +244,11 @@ pub enum Error
     {
         size: usize, max_size: usize
     },
+
+    #[error("Byte offset ({byte_offset}) is too large. Must be < {max_byte_offset}")]
+    ByteOffsetTooLarge
+    {
+        byte_offset: usize,
+        max_byte_offset: usize,
+    },
 }