1 files changed, 240 insertions, 0 deletions
diff --git a/gfx/wr/webrender_build/src/shader.rs b/gfx/wr/webrender_build/src/shader.rs
new file mode 100644
index 0000000000..5db5d738e7
--- /dev/null
+++ b/gfx/wr/webrender_build/src/shader.rs
@@ -0,0 +1,240 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Functionality for managing source code for shaders.
+//!
+//! This module is used during precompilation (build.rs) and regular compilation,
+//! so it has minimal dependencies.
+
+use std::borrow::Cow;
+use std::fs::File;
+use std::io::Read;
+use std::path::Path;
+use std::collections::HashSet;
+use std::collections::hash_map::DefaultHasher;
+use crate::MAX_VERTEX_TEXTURE_WIDTH;
+
+pub use crate::shader_features::*;
+
+lazy_static! {
+    static ref MAX_VERTEX_TEXTURE_WIDTH_STRING: String = MAX_VERTEX_TEXTURE_WIDTH.to_string();
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum ShaderKind {
+    Vertex,
+    Fragment,
+}
+
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
+pub enum ShaderVersion {
+    Gl,
+    Gles,
+}
+
+impl ShaderVersion {
+    /// Return the full variant name, for use in code generation.
+    pub fn variant_name(&self) -> &'static str {
+        match self {
+            ShaderVersion::Gl => "ShaderVersion::Gl",
+            ShaderVersion::Gles => "ShaderVersion::Gles",
+        }
+    }
+}
+
+#[derive(PartialEq, Eq, Hash, Debug, Clone, Default)]
+#[cfg_attr(feature = "serialize_program", derive(Deserialize, Serialize))]
+pub struct ProgramSourceDigest(u64);
+
+impl ::std::fmt::Display for ProgramSourceDigest {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        write!(f, "{:02x}", self.0)
+    }
+}
+
+impl From<DefaultHasher> for ProgramSourceDigest {
+    fn from(hasher: DefaultHasher) -> Self {
+        use std::hash::Hasher;
+        ProgramSourceDigest(hasher.finish())
+    }
+}
+
+const SHADER_IMPORT: &str = "#include ";
+
+pub struct ShaderSourceParser {
+    included: HashSet<String>,
+}
+
+impl ShaderSourceParser {
+    pub fn new() -> Self {
+        ShaderSourceParser {
+            included: HashSet::new(),
+        }
+    }
+
+    /// Parses a shader string for imports. Imports are recursively processed, and
+    /// prepended to the output stream.
+    pub fn parse<F: FnMut(&str), G: Fn(&str) -> Cow<'static, str>>(
+        &mut self,
+        source: Cow<'static, str>,
+        get_source: &G,
+        output: &mut F,
+    ) {
+        for line in source.lines() {
+            if line.starts_with(SHADER_IMPORT) {
+                let imports = line[SHADER_IMPORT.len() ..].split(',');
+
+                // For each import, get the source, and recurse.
+                for import in imports {
+                    if self.included.insert(import.into()) {
+                        let include = get_source(import);
+                        self.parse(include, get_source, output);
+                    } else {
+                        output(&format!("// {} is already included\n", import));
+                    }
+                }
+            } else {
+                output(line);
+                output("\n");
+            }
+        }
+    }
+}
+
+/// Reads a shader source file from disk into a String.
+pub fn shader_source_from_file(shader_path: &Path) -> String {
+    assert!(shader_path.exists(), "Shader not found {:?}", shader_path);
+    let mut source = String::new();
+    File::open(&shader_path)
+        .expect("Shader not found")
+        .read_to_string(&mut source)
+        .unwrap();
+    source
+}
+
+/// Creates heap-allocated strings for both vertex and fragment shaders.
+pub fn build_shader_strings<G: Fn(&str) -> Cow<'static, str>>(
+    gl_version: ShaderVersion,
+    features: &[&str],
+    base_filename: &str,
+    get_source: &G,
+) -> (String, String) {
+   let mut vs_source = String::new();
+   do_build_shader_string(
+       gl_version,
+       features,
+       ShaderKind::Vertex,
+       base_filename,
+       get_source,
+       |s| vs_source.push_str(s),
+   );
+
+   let mut fs_source = String::new();
+   do_build_shader_string(
+       gl_version,
+       features,
+       ShaderKind::Fragment,
+       base_filename,
+       get_source,
+       |s| fs_source.push_str(s),
+   );
+
+   (vs_source, fs_source)
+}
+
+/// Walks the given shader string and applies the output to the provided
+/// callback. Assuming an override path is not used, does no heap allocation
+/// and no I/O.
+pub fn do_build_shader_string<F: FnMut(&str), G: Fn(&str) -> Cow<'static, str>>(
+   gl_version: ShaderVersion,
+   features: &[&str],
+   kind: ShaderKind,
+   base_filename: &str,
+   get_source: &G,
+   mut output: F,
+) {
+   build_shader_prefix_string(gl_version, features, kind, base_filename, &mut output);
+   build_shader_main_string(base_filename, get_source, &mut output);
+}
+
+/// Walks the prefix section of the shader string, which manages the various
+/// defines for features etc.
+pub fn build_shader_prefix_string<F: FnMut(&str)>(
+   gl_version: ShaderVersion,
+   features: &[&str],
+   kind: ShaderKind,
+   base_filename: &str,
+   output: &mut F,
+) {
+    // GLSL requires that the version number comes first.
+    let gl_version_string = match gl_version {
+        ShaderVersion::Gl => "#version 150\n",
+        ShaderVersion::Gles if features.contains(&"TEXTURE_EXTERNAL_ESSL1") => "#version 100\n",
+        ShaderVersion::Gles => "#version 300 es\n",
+    };
+    output(gl_version_string);
+
+    // Insert the shader name to make debugging easier.
+    output("// shader: ");
+    output(base_filename);
+    output(" ");
+    for (i, feature) in features.iter().enumerate() {
+        output(feature);
+        if i != features.len() - 1 {
+            output(",");
+        }
+    }
+    output("\n");
+
+    // Define a constant depending on whether we are compiling VS or FS.
+    let kind_string = match kind {
+        ShaderKind::Vertex => "#define WR_VERTEX_SHADER\n",
+        ShaderKind::Fragment => "#define WR_FRAGMENT_SHADER\n",
+    };
+    output(kind_string);
+
+    // detect which platform we're targeting
+    let is_macos = match std::env::var("CARGO_CFG_TARGET_OS") {
+        Ok(os) => os == "macos",
+        // if this is not called from build.rs (e.g. the gpu_cache_update shader or
+        // if the optimized shader pref is disabled) we want to use the runtime value
+        Err(_) => cfg!(target_os = "macos"),
+    };
+    let is_android = match std::env::var("CARGO_CFG_TARGET_OS") {
+        Ok(os) => os == "android",
+        Err(_) => cfg!(target_os = "android"),
+    };
+    if is_macos {
+        output("#define PLATFORM_MACOS\n");
+    } else if is_android {
+        output("#define PLATFORM_ANDROID\n");
+    }
+
+    // Define a constant for the vertex texture width.
+    output("#define WR_MAX_VERTEX_TEXTURE_WIDTH ");
+    output(&MAX_VERTEX_TEXTURE_WIDTH_STRING);
+    output("U\n");
+
+    // Add any defines for features that were passed by the caller.
+    for feature in features {
+        assert!(!feature.is_empty());
+        output("#define WR_FEATURE_");
+        output(feature);
+        output("\n");
+    }
+}
+
+/// Walks the main .glsl file, including any imports.
+pub fn build_shader_main_string<F: FnMut(&str), G: Fn(&str) -> Cow<'static, str>>(
+   base_filename: &str,
+   get_source: &G,
+   output: &mut F,
+) {
+   let shared_source = get_source(base_filename);
+   ShaderSourceParser::new().parse(
+       shared_source,
+       &|f| get_source(f),
+       output
+   );
+}