feat(engine): add ability to render triangles

1 files changed, 83 insertions, 0 deletions

diff --git a/engine/src/renderer/vertex_buffers.rs b/engine/src/renderer/vertex_buffers.rs
new file mode 100644
index 0000000..a6d1a2c
--- /dev/null
+++ b/engine/src/renderer/vertex_buffers.rs
@@ -0,0 +1,83 @@
+use std::mem::size_of_val;
+
+pub struct VertexBuffers<const CNT: usize>
+{
+    buffers: [gl::types::GLuint; CNT],
+}
+
+impl<const CNT: usize> VertexBuffers<CNT>
+{
+    pub fn new() -> Self
+    {
+        let mut buffers = [gl::types::GLuint::default(); CNT];
+
+        unsafe {
+            #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)]
+            gl::GenBuffers(CNT as gl::types::GLsizei, buffers.as_mut_ptr());
+        };
+
+        Self { buffers }
+    }
+
+    pub fn store(
+        &self,
+        buffer_index: usize,
+        vertices: &[f32],
+        usage: BufferUsage,
+    ) -> Option<()>
+    {
+        let buffer = *self.buffers.get(buffer_index)?;
+
+        unsafe {
+            gl::BindBuffer(gl::ARRAY_BUFFER, 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(),
+            );
+        }
+
+        Some(())
+    }
+}
+
+impl<const CNT: usize> Drop for VertexBuffers<CNT>
+{
+    fn drop(&mut self)
+    {
+        #[allow(clippy::cast_possible_wrap, clippy::cast_possible_truncation)]
+        unsafe {
+            gl::DeleteBuffers(CNT as gl::types::GLsizei, self.buffers.as_ptr());
+        }
+    }
+}
+
+#[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,
+        }
+    }
+}