From 3884921f4ece24a0660afd6fd49bbf4a4aba6a14 Mon Sep 17 00:00:00 2001
From: Pelle Johnsen <pelle.johnsen@gmail.com>
Date: Thu, 23 Jul 2020 17:52:10 +0200
Subject: [PATCH] [glsl-new] handle gl_Position builtin (#114)

* [glsl-new] handle gl_Position builtin

- Also fix width of vec4 type

* [glsl-new] add shader stage as arg to program ctor
---
 src/front/glsl_new/ast.rs          | 15 ++++++--------
 src/front/glsl_new/mod.rs          |  3 ++-
 src/front/glsl_new/parser.rs       | 33 ++++++++++++++++++++++++++----
 src/front/glsl_new/parser_tests.rs | 30 ++++++++++++++++++++-------
 4 files changed, 60 insertions(+), 21 deletions(-)

diff --git a/src/front/glsl_new/ast.rs b/src/front/glsl_new/ast.rs
index 39b28e919b..fb6ab27d41 100644
--- a/src/front/glsl_new/ast.rs
+++ b/src/front/glsl_new/ast.rs
@@ -1,28 +1,30 @@
-use crate::{Arena, Constant, FastHashMap, Function, Handle, Type};
+use crate::{Arena, Constant, FastHashMap, Function, GlobalVariable, Handle, ShaderStage, Type};
 
 #[derive(Debug)]
 pub struct Program {
     pub version: u16,
     pub profile: Profile,
-    pub ext_decls: Vec<ExtDecl>,
+    pub shader_stage: ShaderStage,
     pub lookup_function: FastHashMap<String, Handle<Function>>,
     pub functions: Arena<Function>,
     pub lookup_type: FastHashMap<String, Handle<Type>>,
     pub types: Arena<Type>,
     pub constants: Arena<Constant>,
+    pub global_variables: Arena<GlobalVariable>,
 }
 
 impl Program {
-    pub fn new() -> Program {
+    pub fn new(shader_stage: ShaderStage) -> Program {
         Program {
             version: 0,
             profile: Profile::Core,
-            ext_decls: vec![],
+            shader_stage,
             lookup_function: FastHashMap::default(),
             functions: Arena::<Function>::new(),
             lookup_type: FastHashMap::default(),
             types: Arena::<Type>::new(),
             constants: Arena::<Constant>::new(),
+            global_variables: Arena::<GlobalVariable>::new(),
         }
     }
 }
@@ -31,8 +33,3 @@ impl Program {
 pub enum Profile {
     Core,
 }
-
-#[derive(Debug)]
-pub enum ExtDecl {
-    // FunctionDecl,
-}
diff --git a/src/front/glsl_new/mod.rs b/src/front/glsl_new/mod.rs
index 44ad43b4bd..81e27bb3d1 100644
--- a/src/front/glsl_new/mod.rs
+++ b/src/front/glsl_new/mod.rs
@@ -18,7 +18,7 @@ mod token;
 pub fn parse_str(source: &str, entry: String, stage: ShaderStage) -> Result<Module, ParseError> {
     log::debug!("------ GLSL-pomelo ------");
 
-    let mut program = Program::new();
+    let mut program = Program::new(stage);
     let lex = Lexer::new(source);
     let mut parser = parser::Parser::new(&mut program);
 
@@ -31,6 +31,7 @@ pub fn parse_str(source: &str, entry: String, stage: ShaderStage) -> Result<Modu
     module.functions = program.functions;
     module.types = program.types;
     module.constants = program.constants;
+    module.global_variables = program.global_variables;
 
     // find entry point
     if let Some(entry_handle) = program.lookup_function.get(&entry) {
diff --git a/src/front/glsl_new/parser.rs b/src/front/glsl_new/parser.rs
index f9d2c9b679..55a3636a36 100644
--- a/src/front/glsl_new/parser.rs
+++ b/src/front/glsl_new/parser.rs
@@ -6,8 +6,9 @@ pomelo! {
     //%verbose;
     %include {
         use super::super::{error::ErrorKind, token::*, ast::*};
-        use crate::{Arena, Constant, ConstantInner, Expression, Function, Handle,
-            LocalVariable, ScalarKind, Type, TypeInner, VectorSize};
+        use crate::{Arena, Binding, BuiltIn, Constant, ConstantInner, Expression,
+            Function, GlobalVariable, Handle, LocalVariable, ScalarKind,
+            ShaderStage, StorageClass, Type, TypeInner, VectorSize};
     }
     %token #[derive(Debug)] pub enum Token {};
     %parser pub struct Parser<'a> {};
@@ -72,7 +73,31 @@ pomelo! {
     };
 
     // expression
-    variable_identifier ::= Identifier;
+    variable_identifier ::= Identifier(v) {
+        if v.1.as_str() == "gl_Position" &&
+            (extra.shader_stage == ShaderStage::Vertex ||
+            extra.shader_stage == ShaderStage::Fragment) {
+            extra.global_variables.fetch_or_append(
+                GlobalVariable {
+                    name: Some(v.1),
+                    class: match extra.shader_stage {
+                        ShaderStage::Vertex => StorageClass::Output,
+                        ShaderStage::Fragment => StorageClass::Input,
+                        _ => StorageClass::Input,
+                    },
+                    binding: Some(Binding::BuiltIn(BuiltIn::Position)),
+                    ty: extra.types.fetch_or_append(Type {
+                        name: None,
+                        inner: TypeInner::Vector {
+                            size: VectorSize::Quad,
+                            kind: ScalarKind::Float,
+                            width: 4,
+                        },
+                    }),
+                },
+            );
+        }
+    }
 
     primary_expression ::= variable_identifier;
     primary_expression ::= IntConstant(i) {
@@ -237,7 +262,7 @@ pomelo! {
             inner: TypeInner::Vector {
                 size: VectorSize::Quad,
                 kind: ScalarKind::Float,
-                width: 16,
+                width: 4,
             }
         })
     }
diff --git a/src/front/glsl_new/parser_tests.rs b/src/front/glsl_new/parser_tests.rs
index 9da4677c6c..017df8780e 100644
--- a/src/front/glsl_new/parser_tests.rs
+++ b/src/front/glsl_new/parser_tests.rs
@@ -2,9 +2,10 @@ use super::ast::Program;
 use super::error::ErrorKind;
 use super::lex::Lexer;
 use super::parser;
+use crate::ShaderStage;
 
-fn parse_program(source: &str) -> Result<Program, ErrorKind> {
-    let mut program = Program::new();
+fn parse_program(source: &str, stage: ShaderStage) -> Result<Program, ErrorKind> {
+    let mut program = Program::new(stage);
     let lex = Lexer::new(source);
     let mut parser = parser::Parser::new(&mut program);
 
@@ -18,30 +19,45 @@ fn parse_program(source: &str) -> Result<Program, ErrorKind> {
 #[test]
 fn glsl_parser_version_invalid() {
     assert_eq!(
-        format!("{:?}", parse_program("#version 99000").err().unwrap()),
+        format!(
+            "{:?}",
+            parse_program("#version 99000", ShaderStage::Vertex)
+                .err()
+                .unwrap()
+        ),
         "InvalidVersion(TokenMetadata { line: 0, chars: 9..14 }, 99000)"
     );
 
     assert_eq!(
-        format!("{:?}", parse_program("#version 449").err().unwrap()),
+        format!(
+            "{:?}",
+            parse_program("#version 449", ShaderStage::Vertex)
+                .err()
+                .unwrap()
+        ),
         "InvalidVersion(TokenMetadata { line: 0, chars: 9..12 }, 449)"
     );
 
     assert_eq!(
-        format!("{:?}", parse_program("#version 450 smart").err().unwrap()),
+        format!(
+            "{:?}",
+            parse_program("#version 450 smart", ShaderStage::Vertex)
+                .err()
+                .unwrap()
+        ),
         "InvalidProfile(TokenMetadata { line: 0, chars: 13..18 }, \"smart\")"
     );
 }
 
 #[test]
 fn glsl_parser_version_valid() {
-    let program = parse_program("#version 450\nvoid main() {}").unwrap();
+    let program = parse_program("#version 450\nvoid main() {}", ShaderStage::Vertex).unwrap();
     assert_eq!(
         format!("{:?}", (program.version, program.profile)),
         "(450, Core)"
     );
 
-    let program = parse_program("#version 450 core\nvoid main() {}").unwrap();
+    let program = parse_program("#version 450 core\nvoid main() {}", ShaderStage::Vertex).unwrap();
     assert_eq!(
         format!("{:?}", (program.version, program.profile)),
         "(450, Core)"