From a54faaa3218ea599cb21967dbb8aea0f73cd7fa0 Mon Sep 17 00:00:00 2001
From: Jacob Hughes <j@distanthills.org>
Date: Mon, 16 Oct 2023 09:51:19 -0400
Subject: [PATCH] debug_printf: glsl-out

---
 src/back/glsl/features.rs | 22 ++++++++++++++++++++++
 src/back/glsl/mod.rs      | 10 ++++++++--
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/back/glsl/features.rs b/src/back/glsl/features.rs
index 4aac9b2e67..ec9f2e8485 100644
--- a/src/back/glsl/features.rs
+++ b/src/back/glsl/features.rs
@@ -43,6 +43,8 @@ bitflags::bitflags! {
         const IMAGE_SIZE = 1 << 20;
         /// Dual source blending
         const DUAL_SOURCE_BLENDING = 1 << 21;
+        /// Debug Printf
+        const DEBUG_PRINTF = 1 << 22;
     }
 }
 
@@ -235,6 +237,10 @@ impl FeaturesManager {
             // https://registry.khronos.org/OpenGL/extensions/EXT/EXT_blend_func_extended.txt
             writeln!(out, "#extension GL_EXT_blend_func_extended : require")?;
         }
+        if self.0.contains(Features::DEBUG_PRINTF) {
+            // https://github.com/KhronosGroup/GLSL/blob/master/extensions/ext/GLSL_EXT_debug_printf.txt
+            writeln!(out, "#extension GL_EXT_debug_printf : enable")?;
+        }
 
         Ok(())
     }
@@ -407,6 +413,22 @@ impl<'a, W> Writer<'a, W> {
             ..
         } = self;
 
+        for block in module
+            .functions
+            .iter()
+            .map(|(_, f)| &f.body)
+            .chain(std::iter::once(&entry_point.function.body))
+        {
+            for statement in block.iter() {
+                match *statement {
+                    crate::Statement::DebugPrintf { .. } => {
+                        features.request(Features::DEBUG_PRINTF)
+                    }
+                    _ => {}
+                }
+            }
+        }
+
         // Loop trough all expressions in both functions and the entry point
         // to check for needed features
         for (expressions, info) in module
diff --git a/src/back/glsl/mod.rs b/src/back/glsl/mod.rs
index 7fe7b11135..af77ffef95 100644
--- a/src/back/glsl/mod.rs
+++ b/src/back/glsl/mod.rs
@@ -2238,8 +2238,14 @@ impl<'a, W: Write> Writer<'a, W> {
                 writeln!(self.out, ");")?;
             }
             Statement::RayQuery { .. } => unreachable!(),
-            Statement::DebugPrintf { .. } => {
-                return Err(Error::Custom("debugPrintf is not implemented".to_string()));
+            Statement::DebugPrintf {
+                ref format,
+                ref arguments,
+            } => {
+                write!(self.out, "{level}")?;
+                write!(self.out, "debugPrintfEXT(\"{format}\",")?;
+                self.write_slice(arguments, |this, _, arg| this.write_expr(*arg, ctx))?;
+                writeln!(self.out, ");")?
             }
         }