From 7b2da82718b2c33a63a84762c9f990a12f3923f6 Mon Sep 17 00:00:00 2001
From: Michael Hills <MichaelHills@users.noreply.github.com>
Date: Wed, 2 Sep 2020 04:06:15 +1000
Subject: [PATCH] iOS: use shaderc-rs for glsl to spirv compilation (#324)

---
 crates/bevy_render/Cargo.toml           | 12 ++++++--
 crates/bevy_render/src/shader/shader.rs | 39 +++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/crates/bevy_render/Cargo.toml b/crates/bevy_render/Cargo.toml
index c3a9b8111413e..623c8f69c4ccd 100644
--- a/crates/bevy_render/Cargo.toml
+++ b/crates/bevy_render/Cargo.toml
@@ -32,16 +32,16 @@ image = { version = "0.23", default-features = false }
 log = { version = "0.4", features = ["release_max_level_info"] }
 uuid = { version = "0.8", features = ["v4", "serde"] }
 serde = { version = "1", features = ["derive"] }
-bitflags = "1.0"
+bitflags = "1.2.1"
 smallvec = "1.4.0"
 # TODO: replace once_cell with std equivalent if/when this lands: https://github.com/rust-lang/rfcs/pull/2788
 once_cell = "1.4.0"
-downcast-rs = "1.1.1"
+downcast-rs = "1.2.0"
 thiserror = "1.0"
 anyhow = "1.0"
 hex = "0.4.2"
 hexasphere = "1.0.0"
-parking_lot = "0.10"
+parking_lot = "0.11.0"
 
 [dependencies.naga]
 # Temporarily git, either get kvark to publish a new version, or mirror
@@ -53,6 +53,12 @@ features = ["glsl-new", "spirv"]
 [dev-dependencies]
 pretty_assertions = "0.6.1"
 
+# [target.'cfg(not(target_os = "ios"))'.dependencies]
+# bevy-glsl-to-spirv = "0.1.7"
+
+# [target.'cfg(target_os = "ios")'.dependencies]
+# shaderc = "0.6.2"
+
 [features]
 # default = ["bevy-glsl-to-spirv", "spirv-reflect"]
 default = ["naga-glsl", "naga-reflect"]
diff --git a/crates/bevy_render/src/shader/shader.rs b/crates/bevy_render/src/shader/shader.rs
index da450c3322513..f76990b2e8477 100644
--- a/crates/bevy_render/src/shader/shader.rs
+++ b/crates/bevy_render/src/shader/shader.rs
@@ -37,6 +37,7 @@ impl Into<bevy_glsl_to_spirv::ShaderType> for ShaderStage {
     }
 }
 
+#[cfg(not(target_os = "ios"))]
 fn glsl_to_spirv(
     glsl_source: &str,
     stage: ShaderStage,
@@ -80,6 +81,44 @@ fn glsl_to_spirv(
     }
 }
 
+#[cfg(target_os = "ios")]
+impl Into<shaderc::ShaderKind> for ShaderStage {
+    fn into(self) -> shaderc::ShaderKind {
+        match self {
+            ShaderStage::Vertex => shaderc::ShaderKind::Vertex,
+            ShaderStage::Fragment => shaderc::ShaderKind::Fragment,
+            ShaderStage::Compute => shaderc::ShaderKind::Compute,
+        }
+    }
+}
+
+#[cfg(target_os = "ios")]
+fn glsl_to_spirv(
+    glsl_source: &str,
+    stage: ShaderStage,
+    shader_defs: Option<&[String]>,
+) -> Vec<u32> {
+    let mut compiler = shaderc::Compiler::new().unwrap();
+    let mut options = shaderc::CompileOptions::new().unwrap();
+    if let Some(shader_defs) = shader_defs {
+        for def in shader_defs.iter() {
+            options.add_macro_definition(def, None);
+        }
+    }
+
+    let binary_result = compiler
+        .compile_into_spirv(
+            glsl_source,
+            stage.into(),
+            "shader.glsl",
+            "main",
+            Some(&options),
+        )
+        .unwrap();
+
+    binary_result.as_binary().to_vec()
+}
+
 fn bytes_to_words(bytes: &[u8]) -> Vec<u32> {
     let mut words = Vec::new();
     for bytes4 in bytes.chunks(4) {