port frame begin/end to safe rust

citro3d/Cargo.toml

@@ -2,7 +2,6 @@
 name = "citro3d"
 version = "0.1.0"
 edition = "2021"
-authors = [""]
 
 [dependencies]
 bitflags = "1.3.2"

citro3d/examples/triangle.rs

@@ -44,6 +44,9 @@ const VERTICES: &[Vertex] = &[
     },
 ];
 
+static SHADER_BYTES: &[u8] =
+    include_bytes!(concat!(env!("OUT_DIR"), "/examples/assets/vshader.shbin"));
+
 fn main() {
     ctru::init();
 
@@ -78,14 +81,7 @@ fn main() {
             break;
         }
 
-        unsafe {
-            citro3d_sys::C3D_FrameBegin(
-                citro3d_sys::C3D_FRAME_SYNCDRAW
-                    .try_into()
-                    .expect("const is valid u8"),
-            );
-        }
-
+        instance.render_frame_with(|instance| {
             let clear_color: u32 = 0x7F_7F_7F_FF;
             render_target.clear(ClearFlags::ALL, clear_color, 0);
 
@@ -94,22 +90,16 @@ fn main() {
                 .expect("failed to set render target");
 
             scene_render(uloc_projection.into(), &projection);
-
-        unsafe {
-            citro3d_sys::C3D_FrameEnd(0);
-        }
+        });
     }
 
     scene_exit(vbo_data, program, vshader_dvlb);
 }
 
-static SHBIN_BYTES: &[u8] =
-    include_bytes!(concat!(env!("OUT_DIR"), "/examples/assets/vshader.shbin"));
-
 fn scene_init() -> (shaderProgram_s, i8, C3D_Mtx, *mut libc::c_void, *mut DVLB_s) {
     // Load the vertex shader, create a shader program and bind it
     unsafe {
-        let mut shader_bytes = SHBIN_BYTES.to_owned();
+        let mut shader_bytes = SHADER_BYTES.to_owned();
 
         // Assume the data is aligned properly...
         let vshader_dvlb = citro3d_sys::DVLB_ParseFile(

citro3d/src/lib.rs

@@ -74,6 +74,25 @@ impl Instance {
             Err(Error::InvalidRenderTarget)
         }
     }
+
+    /// Render a frame. The passed in function/closure can mutate the instance,
+    /// such as to [select a render target](Self::select_render_target).
+    pub fn render_frame_with(&mut self, f: impl FnOnce(&mut Self)) {
+        unsafe {
+            citro3d_sys::C3D_FrameBegin(
+                // TODO: begin + end flags should be configurable
+                citro3d_sys::C3D_FRAME_SYNCDRAW
+                    .try_into()
+                    .expect("const is valid u8"),
+            );
+        }
+
+        f(self);
+
+        unsafe {
+            citro3d_sys::C3D_FrameEnd(0);
+        }
+    }
 }
 
 impl Drop for Instance {