🚧 Work on pass manager idea

Cargo.lock

@@ -134,6 +134,11 @@ dependencies = [
  "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "maplit"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "memchr"
 version = "2.2.1"
@@ -199,6 +204,7 @@ dependencies = [
  "gl 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "glam 0.8.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "iota 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "maplit 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "nom 5.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "png 0.15.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -423,6 +429,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum lexical-core 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "2304bccb228c4b020f3a4835d247df0a02a7c4686098d4167762cfbbe4c5cb14"
 "checksum libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)" = "d515b1f41455adea1313a4a2ac8a8a477634fbae63cc6100e3aebb207ce61558"
 "checksum log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)" = "14b6052be84e6b71ab17edffc2eeabf5c2c3ae1fdb464aae35ac50c67a44e1f7"
+"checksum maplit 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "3e2e65a1a2e43cfcb47a895c4c8b10d1f4a61097f9f254f183aee60cad9c651d"
 "checksum memchr 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "88579771288728879b57485cc7d6b07d648c9f0141eb955f8ab7f9d45394468e"
 "checksum nodrop 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)" = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
 "checksum nom 5.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c433f4d505fe6ce7ff78523d2fa13a0b9f2690e181fc26168bcbe5ccc5d14e07"

Cargo.toml

@@ -15,6 +15,7 @@ glam = "0.8.5"
 
 iota = "0.2.1"
 
+maplit = "1.0.2"
 # TODO: Drop nom depend. It's way overkill for iqm.
 nom = "5.1.0"
 

src/bin/pumpkin.rs

@@ -1,3 +1,6 @@
+#[macro_use] 
+extern crate maplit;
+
 use glam::{Mat4, Vec3, Vec4};
 
 use sdl2::event::Event;
@@ -149,6 +152,161 @@ struct RenderableArrow {
 	inv_model_mat: Mat4,
 }
 
+#[derive (Copy, Clone)]
+pub enum FrontFace {
+	Cw,
+	Ccw,
+}
+
+impl From <FrontFace> for u32 {
+	fn from (v: FrontFace) -> Self {
+		use FrontFace::*;
+		{
+		use gl::*;
+		match v {
+			Cw => CW,
+			Ccw => CCW,
+		}
+		}
+	}
+}
+
+#[derive (Copy, Clone)]
+pub enum StencilOp {
+	Keep, 
+	Zero, 
+	Replace, 
+	Incr, 
+	Decr, 
+	Invert,
+	IncrWrap, 
+	DecrWrap,
+}
+
+impl From <StencilOp> for u32 {
+	fn from (v: StencilOp) -> Self {
+		use StencilOp::*;
+		{
+		use gl::*;
+		match v {
+			Keep => KEEP,
+			Zero => ZERO,
+			Replace => REPLACE,
+			Incr => INCR,
+			Decr => DECR,
+			Invert => INVERT,
+			IncrWrap => INCR_WRAP,
+			DecrWrap => DECR_WRAP,
+		}
+		}
+	}
+}
+
+#[derive (Copy, Clone)]
+pub enum StencilFunc {
+	Never, 
+	Always, 
+	Less, 
+	LessEqual, 
+	Equal, 
+	Greater, 
+	GreaterEqual,
+	NotEqual,
+}
+
+impl From <StencilFunc> for u32 {
+	fn from (v: StencilFunc) -> Self {
+		use StencilFunc::*;
+		{
+		use gl::*;
+		match v {
+			Never => NEVER,
+			Always => ALWAYS,
+			Less => LESS,
+			LessEqual => LEQUAL,
+			Equal => EQUAL,
+			Greater => GREATER,
+			GreaterEqual => GEQUAL,
+			NotEqual => NOTEQUAL,
+		}
+		}
+	}
+}
+
+pub struct StencilOpState {
+	sfail: StencilOp,
+	dpfail: StencilOp,
+	dppass: StencilOp,
+}
+
+pub struct StencilFuncState {
+	func: StencilFunc,
+	reference: i32,
+	mask: u32,
+}
+
+pub struct StencilState {
+	op: StencilOpState,
+	func: StencilFuncState,
+}
+
+// Anything that's None is "unknown"
+
+pub struct GlState {
+	flags: HashMap <u32, bool>,
+	front_face: Option <FrontFace>,
+	stencil: Option <StencilState>,
+}
+
+pub struct Pass <'a> {
+	shader: &'a ShaderClosure,
+	
+	// Anything that's None is "don't care"
+	
+	required_state: GlState,
+}
+
+impl Pass <'_> {
+	pub fn apply_slow (&self) {
+		let state = &self.required_state;
+		
+		for (flag, value) in state.flags.iter () {
+			if *value {
+				glezz::enable (*flag);
+			}
+			else {
+				glezz::disable (*flag);
+			}
+		}
+		
+		match state.front_face {
+			Some (v) => glezz::front_face (v.into ()),
+			_ => (),
+		}
+		
+		match &state.stencil {
+			Some (v) => {
+				let func = &v.func;
+				let op = &v.op;
+				
+				unsafe {
+					gl::StencilFunc (
+						func.func.into (), 
+						func.reference.into (), 
+						func.mask.into ()
+					);
+					gl::StencilOp (
+						op.sfail.into (), 
+						op.dpfail.into (), 
+						op.dppass.into ()
+					);
+				}
+			},
+			_ => (),
+		}
+	}
+}
+
 struct GameGraphics {
 	shader_diffuse: ShaderClosure,
 	shader_shadow: ShaderClosure,
@@ -305,6 +463,83 @@ impl GameGraphics {
 		
 		glezz::clear_color (1.0f32, 0.0f32, 1.0f32, 1.0f32);
 		glezz::clear (gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT | gl::STENCIL_BUFFER_BIT);
+		
+		let passes = vec! [
+			Pass {
+				shader: &self.shader_diffuse,
+				required_state: GlState {
+					flags: hashmap! {
+						gl::STENCIL_TEST => false,
+					},
+					front_face: Some (FrontFace::Cw),
+					stencil: None,
+				},
+			},
+			Pass {
+				shader: &self.shader_shadow,
+				required_state: GlState {
+					flags: hashmap! {
+						gl::STENCIL_TEST => true,
+					},
+					front_face: Some (FrontFace::Ccw),
+					stencil: Some (StencilState {
+						func: StencilFuncState {
+							func: StencilFunc::Always,
+							reference: 1,
+							mask: 1,
+						},
+						op: StencilOpState {
+							sfail: StencilOp::Keep,
+							dpfail: StencilOp::Keep,
+							dppass: StencilOp::Replace,
+						},
+					}),
+				},
+			},
+			Pass {
+				shader: &self.shader_shadow,
+				required_state: GlState {
+					flags: hashmap! {
+						gl::STENCIL_TEST => true,
+					},
+					front_face: Some (FrontFace::Cw),
+					stencil: Some (StencilState {
+						func: StencilFuncState {
+							func: StencilFunc::NotEqual,
+							reference: 0,
+							mask: 1,
+						},
+						op: StencilOpState {
+							sfail: StencilOp::Keep,
+							dpfail: StencilOp::Keep,
+							dppass: StencilOp::Keep,
+						},
+					}),
+				},
+			},
+			Pass {
+				shader: &self.shader_shadow,
+				required_state: GlState {
+					flags: hashmap! {
+						gl::STENCIL_TEST => true,
+					},
+					front_face: Some (FrontFace::Cw),
+					stencil: Some (StencilState {
+						func: StencilFuncState {
+							func: StencilFunc::Equal,
+							reference: 0,
+							mask: 1,
+						},
+						op: StencilOpState {
+							sfail: StencilOp::Keep,
+							dpfail: StencilOp::Keep,
+							dppass: StencilOp::Keep,
+						},
+					}),
+				},
+			},
+		];
+		
 		glezz::enable (gl::CULL_FACE);
 		
 		let pumpkin_model_mat = 
@@ -324,9 +559,8 @@ impl GameGraphics {
 			let unis = shader_vars.unis;
 			let attrs = shader_vars.attrs;
 			
-			// Pass 1 - Draw the world except the ground plane
+			// Pass 0 - Draw the world except the ground plane
-			glezz::disable (gl::STENCIL_TEST);
+			passes [0].apply_slow ();
-			glezz::front_face (gl::CW);
 			
 			let mvp = view_mat * pumpkin_model_mat;
 			glezz::uniform_matrix_4fv (unis [&MVP], &mvp);
@@ -385,13 +619,9 @@ impl GameGraphics {
 			let unis = shader_vars.unis;
 			let attrs = shader_vars.attrs;
 			
-			// Pass 2: Draw shadows into stencil buffer
+			// Pass 1: Draw shadows into stencil buffer
-			glezz::front_face (gl::CCW);
+			passes [1].apply_slow ();
-			glezz::enable (gl::STENCIL_TEST);
 			unsafe {
-				gl::StencilFunc (gl::ALWAYS, 1, 1);
-				gl::StencilOp (gl::KEEP, gl::KEEP, gl::REPLACE);
-				
 				gl::ColorMask (0, 0, 0, 0);
 				gl::DepthMask (0);
 				gl::StencilMask (1);
@@ -421,16 +651,13 @@ impl GameGraphics {
 			let unis = shader_vars.unis;
 			let attrs = shader_vars.attrs;
 			
-			// Pass 3: Draw lit ground
+			// Pass 2: Draw lit ground
+			passes [2].apply_slow ();
 			unsafe {
 				gl::ColorMask (255, 255, 255, 255);
 				gl::DepthMask (1);
-				gl::StencilFunc (gl::NOTEQUAL, 0, 1);
-				gl::StencilOp (gl::KEEP, gl::KEEP, gl::KEEP);
 			}
 			
-			glezz::front_face (gl::CW);
-			
 			let inverse_pumpkin = pumpkin_model_mat.inverse ();
 			
 			let object_space_light = make_object_space_vec (&inverse_pumpkin, &light);
@@ -449,11 +676,9 @@ impl GameGraphics {
 			glezz::uniform_3fv (unis [&OBJECT_SPACE_LIGHT], &Vec3::from ((0.0, 0.0, 0.0)));
 			self.mesh_pitch.draw (attrs, self.grass_index);
 			
-			// Pass 4: Draw shadowed ground
+			// Pass 3: Draw shadowed ground
-			unsafe {
+			passes [3].apply_slow ();
-				gl::StencilFunc (gl::EQUAL, 0, 1);
+			
-				gl::StencilOp (gl::KEEP, gl::KEEP, gl::KEEP);
-			}
 			glezz::uniform_3fv (unis [&OBJECT_SPACE_LIGHT], &object_space_light);
 			self.mesh_pitch.draw (attrs, self.grass_index);
 		});
@@ -574,7 +799,11 @@ mod tests {
 	use super::*;
 	
 	#[test]
-	pub fn iqm () {
+	pub fn sizes () {
+		use std::mem;
 		
+		assert_eq! (8, mem::size_of::<Option <u32>>());
+		assert_eq! (1, mem::size_of::<FrontFace>());
+		assert_eq! (1, mem::size_of::<Option <FrontFace>>());
 	}
 }