♻️ Make it harder to access the wrong shader vars by accident

src/bin/pumpkin.rs

@@ -1,5 +1,4 @@
 use glam::{Mat4, Vec3, Vec4};
-use rand::Rng;
 
 use sdl2::event::Event;
 use sdl2::keyboard::{Keycode, Scancode};
@@ -129,6 +128,43 @@ where P: AsRef <std::path::Path>
 	RenderableModel::from_iqm (&model)
 }
 
+struct ShaderClosure {
+	program: ShaderProgram,
+	uniforms: HashMap <u32, i32>,
+	attributes: HashMap <String, Option <u32>>,
+}
+
+struct BorrowedShaderVars <'a> {
+	unis: &'a HashMap <u32, i32>,
+	attrs: &'a HashMap <String, Option <u32>>,
+}
+
+impl ShaderClosure {
+	pub fn new (
+		program: ShaderProgram, 
+		uniforms: HashMap <u32, i32>,
+		attributes: HashMap <String, Option <u32>>
+	) -> Self
+	{
+		Self {
+			program,
+			uniforms,
+			attributes,
+		}
+	}
+	
+	pub fn with <F> (&self, callback: F)
+	where F: Fn (BorrowedShaderVars)
+	{
+		self.program.use_program ();
+		
+		callback (BorrowedShaderVars {
+			unis: &self.uniforms,
+			attrs: &self.attributes,
+		});
+	}
+}
+
 fn main () {
 	let sdl_context = sdl2::init ().unwrap ();
 	let video_subsystem = sdl_context.video ().unwrap ();
@@ -171,6 +207,18 @@ fn main () {
 		ShaderProgram::new (&vert_shader, &frag_shader).unwrap ()
 	};
 	
+	let attrs = shader_program.get_attribute_locations (vec! [
+		"pos",
+		"uv",
+		"normal",
+	].into_iter ());
+	
+	let shadow_attrs = shadow_shader.get_attribute_locations (vec! [
+		"pos",
+		"uv",
+		"normal",
+	].into_iter ());
+	
 	let uni_lookup: HashMap <_, &str> = HashMap::from_iter ({
 		use uniforms::*;
 		vec! [
@@ -204,17 +252,12 @@ fn main () {
 		unis
 	};
 	
-	let attrs = shader_program.get_attribute_locations (vec! [
-		"pos",
-		"uv",
-		"normal",
-	].into_iter ());
+	glezz::enable_vertex_attrib_array (attrs ["pos"]);
+	glezz::enable_vertex_attrib_array (attrs ["uv"]);
+	glezz::enable_vertex_attrib_array (attrs ["normal"]);
 	
-	let shadow_attrs = shadow_shader.get_attribute_locations (vec! [
-		"pos",
-		"uv",
-		"normal",
-	].into_iter ());
+	let shader_diffuse = ShaderClosure::new (shader_program, unis, attrs);
+	let shader_shadow = ShaderClosure::new (shadow_shader, shadow_unis, shadow_attrs);
 	
 	let texture = Texture::from_file ("sky.png");
 	texture.bind ();
@@ -275,10 +318,6 @@ fn main () {
 		(colors, grass_index.unwrap ())
 	};
 	
-	glezz::enable_vertex_attrib_array (attrs ["pos"]);
-	glezz::enable_vertex_attrib_array (attrs ["uv"]);
-	glezz::enable_vertex_attrib_array (attrs ["normal"]);
-	
 	glezz::enable (gl::DEPTH_TEST);
 	glezz::enable (gl::TEXTURE_2D);
 	
@@ -343,10 +382,12 @@ fn main () {
 		
 		let world_model_mat = Mat4::identity ();
 		
-		{
 		use uniforms::*;
 		
-			shader_program.use_program ();
+		shader_diffuse.with (|shader_vars| {
+			let unis = shader_vars.unis;
+			let attrs = shader_vars.attrs;
+			
 			glezz::disable (gl::STENCIL_TEST);
 			glezz::front_face (gl::CW);
 			
@@ -398,25 +439,34 @@ fn main () {
 				gl::DepthMask (0);
 				gl::StencilMask (1);
 			}
-			shadow_shader.use_program ();
+		});
+		
+		shader_shadow.with (|shader_vars| {
+			let unis = shader_vars.unis;
+			let attrs = shader_vars.attrs;
 			
 			let view_mat = view_mat * shadow_mat;
 			
 			let mvp = view_mat * pumpkin_model_mat;
-			glezz::uniform_matrix_4fv (shadow_unis [&MVP], &mvp);
+			glezz::uniform_matrix_4fv (unis [&MVP], &mvp);
 			
-			mesh_pumpkin.draw_all (&shadow_attrs, |_| true);
+			mesh_pumpkin.draw_all (&attrs, |_| true);
 			
 			let mvp = view_mat * world_model_mat;
-			glezz::uniform_matrix_4fv (shadow_unis [&MVP], &mvp);
+			glezz::uniform_matrix_4fv (unis [&MVP], &mvp);
 			
-			mesh_pitch.draw_all (&shadow_attrs, |i| i != grass_index);
+			mesh_pitch.draw_all (&attrs, |i| i != grass_index);
 			
 			unsafe {
 				gl::ColorMask (255, 255, 255, 255);
 				gl::DepthMask (1);
 			}
-			shader_program.use_program ();
+		});
+		
+		shader_diffuse.with (|shader_vars| {
+			let unis = shader_vars.unis;
+			let attrs = shader_vars.attrs;
+			
 			glezz::front_face (gl::CW);
 			
 			let inverse_pumpkin = pumpkin_model_mat.inverse ();
@@ -447,7 +497,7 @@ fn main () {
 			}
 			glezz::uniform_3fv (unis [&OBJECT_SPACE_LIGHT], &object_space_light);
 			mesh_pitch.draw (&attrs, grass_index);
-		}
+		});
 		
 		window.gl_swap_window ();
 		

src/shader.rs

@@ -119,6 +119,8 @@ impl ShaderProgram {
 		}
 	}
 	
+	// 'use' is a keyword
+	
 	pub fn use_program (&self) {
 		unsafe {
 			gl::UseProgram (self.id);