Use a simple trait for binding uniforms

It's not much but it should be extensible enough to apply for other
uniform types. We might want a generic impl for &[u8] or something
as well to support custom uniform types, but that gets trickier.

citro3d/examples/triangle.rs

@@ -91,7 +91,7 @@ fn main() {
 
     scene_init(&mut program);
 
-    let projection_uniform_idx = program.get_uniform_location("projection").unwrap();
+    let projection_uniform_idx = program.get_uniform("projection").unwrap();
 
     while apt.main_loop() {
         hid.scan_input();
@@ -109,7 +109,7 @@ fn main() {
                 let clear_color: u32 = 0x7F_7F_7F_FF;
                 target.clear(ClearFlags::ALL, clear_color, 0);
 
-                instance.update_vertex_uniform_mat4x4(projection_uniform_idx, projection);
+                instance.bind_vertex_uniform(projection_uniform_idx, projection);
 
                 instance.set_attr_info(&attr_info);
 

citro3d/src/lib.rs

@@ -8,10 +8,13 @@ pub mod error;
 pub mod math;
 pub mod render;
 pub mod shader;
+pub mod uniform;
 
 pub use error::{Error, Result};
 pub use math::Matrix;
 
+use self::uniform::Uniform;
+
 pub mod macros {
     //! Helper macros for working with shaders.
     pub use citro3d_macros::*;
@@ -123,17 +126,12 @@ impl Instance {
         }
     }
 
-    // TODO: need separate versions for vertex/geometry and different dimensions?
-    // Maybe we could do something nicer with const generics, or something, although
-    // it will probably be tricker
-    pub fn update_vertex_uniform_mat4x4(&mut self, index: i8, matrix: &Matrix) {
-        unsafe {
-            citro3d_sys::C3D_FVUnifMtx4x4(
-                ctru_sys::GPU_VERTEX_SHADER,
-                index.into(),
-                matrix.as_raw(),
-            )
+    pub fn bind_vertex_uniform(&mut self, index: uniform::Index, uniform: &impl Uniform) {
+        uniform.bind(self, shader::Type::Vertex, index);
     }
+
+    pub fn bind_geometry_uniform(&mut self, index: uniform::Index, uniform: &impl Uniform) {
+        uniform.bind(self, shader::Type::Geometry, index);
     }
 }
 

citro3d/src/shader.rs

@@ -8,10 +8,12 @@ use std::error::Error;
 use std::ffi::CString;
 use std::mem::MaybeUninit;
 
+use crate::uniform;
+
 /// A PICA200 shader program. It may have one or both of:
 ///
-/// * A vertex shader [`Library`]
-/// * A geometry shader [`Library`]
+/// * A [vertex](Type::Vertex) shader [`Library`]
+/// * A [geometry](Type::Geometry) shader [`Library`]
 ///
 /// The PICA200 does not support user-programmable fragment shaders.
 pub struct Program {
@@ -73,7 +75,7 @@ impl Program {
     ///
     /// * If the given `name` contains a null byte
     /// * If a uniform with the given `name` could not be found
-    pub fn get_uniform_location(&self, name: &str) -> crate::Result<i8> {
+    pub fn get_uniform(&self, name: &str) -> crate::Result<uniform::Index> {
         let vertex_instance = unsafe { (*self.as_raw()).vertexShader };
         assert!(
             !vertex_instance.is_null(),
@@ -88,14 +90,15 @@ impl Program {
         if idx < 0 {
             Err(crate::Error::NotFound)
         } else {
-            Ok(idx)
+            Ok(idx.into())
         }
     }
-    // TODO: pub(crate)
-    pub fn as_raw(&self) -> *const ctru_sys::shaderProgram_s {
+
+    pub(crate) fn as_raw(&self) -> *const ctru_sys::shaderProgram_s {
         &self.program
     }
 
+    // TODO: pub(crate)
     pub fn as_raw_mut(&mut self) -> *mut ctru_sys::shaderProgram_s {
         &mut self.program
     }
@@ -109,6 +112,19 @@ impl Drop for Program {
     }
 }
 
+/// The type of a shader.
+#[repr(u32)]
+pub enum Type {
+    Vertex = ctru_sys::GPU_VERTEX_SHADER,
+    Geometry = ctru_sys::GPU_GEOMETRY_SHADER,
+}
+
+impl From<Type> for u32 {
+    fn from(value: Type) -> Self {
+        value as u32
+    }
+}
+
 /// A PICA200 Shader Library (commonly called DVLB). This can be comprised of
 /// one or more [`Entrypoint`]s, but most commonly has one vertex shader and an
 /// optional geometry shader.
@@ -131,7 +147,7 @@ impl Library {
                 // SAFETY: we're trusting the parse implementation doesn't mutate
                 // the contents of the data. From a quick read it looks like that's
                 // correct and it should just take a const arg in the API.
-                aligned.as_ptr() as *mut _,
+                aligned.as_ptr().cast_mut(),
                 aligned.len().try_into()?,
             )
         }))

citro3d/src/uniform.rs

@@ -0,0 +1,33 @@
+use crate::{shader, Instance, Matrix};
+
+#[derive(Copy, Clone, Debug)]
+pub struct Index(i8);
+
+impl From<i8> for Index {
+    fn from(value: i8) -> Self {
+        Self(value)
+    }
+}
+
+impl From<Index> for i32 {
+    fn from(value: Index) -> Self {
+        value.0.into()
+    }
+}
+
+mod private {
+    use crate::Matrix;
+
+    pub trait Sealed {}
+    impl Sealed for Matrix {}
+}
+
+pub trait Uniform: private::Sealed {
+    fn bind(&self, instance: &mut Instance, shader_type: shader::Type, index: Index);
+}
+
+impl Uniform for Matrix {
+    fn bind(&self, _instance: &mut Instance, type_: shader::Type, index: Index) {
+        unsafe { citro3d_sys::C3D_FVUnifMtx4x4(type_.into(), index.into(), self.as_raw()) }
+    }
+}