From 88d6ae3e4854c5fb4b37f75a29aba4f13dcfb382 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Mon, 19 Feb 2024 23:06:17 +0100
Subject: refactor(engine): create shaders on start

---
 engine/src/shader.rs | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 engine/src/shader.rs

(limited to 'engine/src/shader.rs')

diff --git a/engine/src/shader.rs b/engine/src/shader.rs
new file mode 100644
index 0000000..428e5a8
--- /dev/null
+++ b/engine/src/shader.rs
@@ -0,0 +1,156 @@
+use std::collections::hash_map::DefaultHasher;
+use std::fs::read_to_string;
+use std::hash::{Hash, Hasher};
+use std::path::{Path, PathBuf};
+
+use crate::shader_preprocessor::{Error as ShaderPreprocessorError, ShaderPreprocessor};
+
+/// Shader program
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Default)]
+pub struct Program
+{
+    shaders: Vec<Shader>,
+}
+
+impl Program
+{
+    #[must_use]
+    pub fn new() -> Self
+    {
+        Self { shaders: Vec::new() }
+    }
+
+    pub fn push_shader(&mut self, shader: Shader)
+    {
+        self.shaders.push(shader);
+    }
+
+    pub fn append_shaders(&mut self, shaders: impl IntoIterator<Item = Shader>)
+    {
+        self.shaders.extend(shaders);
+    }
+
+    #[must_use]
+    pub fn shaders(&self) -> &[Shader]
+    {
+        &self.shaders
+    }
+
+    pub(crate) fn u64_hash(&self) -> u64
+    {
+        let mut hasher = DefaultHasher::new();
+
+        self.hash(&mut hasher);
+
+        hasher.finish()
+    }
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
+pub struct Shader
+{
+    kind: Kind,
+    source: String,
+    file: PathBuf,
+}
+
+impl Shader
+{
+    /// Reads a shader from the specified source file.
+    ///
+    /// # Errors
+    /// Will return `Err` if:
+    /// - Reading the file fails
+    /// - The shader source is not ASCII
+    pub fn read_shader_file(kind: Kind, shader_file: &Path) -> Result<Self, Error>
+    {
+        let source = read_to_string(shader_file).map_err(|err| Error::ReadFailed {
+            source: err,
+            shader_file: shader_file.to_path_buf(),
+        })?;
+
+        if !source.is_ascii() {
+            return Err(Error::SourceNotAscii);
+        }
+
+        Ok(Self {
+            kind,
+            source,
+            file: shader_file.to_path_buf(),
+        })
+    }
+
+    /// Preprocesses the shaders.
+    ///
+    /// # Errors
+    /// Returns `Err` if preprocessing fails.
+    pub fn preprocess(self) -> Result<Self, Error>
+    {
+        let shader_preprocessor = ShaderPreprocessor::new(
+            self.file
+                .parent()
+                .ok_or(Error::SourcePathHasNoParent)?
+                .to_path_buf(),
+        );
+
+        let source_preprocessed = shader_preprocessor
+            .preprocess(self.source, &self.file)
+            .map_err(|err| Error::PreprocessFailed {
+                source: err,
+                shader_file: self.file.clone(),
+            })?;
+
+        Ok(Self {
+            kind: self.kind,
+            source: source_preprocessed,
+            file: self.file.clone(),
+        })
+    }
+
+    #[must_use]
+    pub fn kind(&self) -> Kind
+    {
+        self.kind
+    }
+
+    #[must_use]
+    pub fn source(&self) -> &str
+    {
+        &self.source
+    }
+}
+
+/// Shader kind.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Kind
+{
+    Vertex,
+    Fragment,
+}
+
+/// Shader error
+#[derive(Debug, thiserror::Error)]
+pub enum Error
+{
+    #[error("Failed to read shader {}", shader_file.display())]
+    ReadFailed
+    {
+        #[source]
+        source: std::io::Error,
+        shader_file: PathBuf,
+    },
+
+    #[error("Shader source is not ASCII")]
+    SourceNotAscii,
+
+    #[error("Failed to preprocess shader {}", shader_file.display())]
+    PreprocessFailed
+    {
+        #[source]
+        source: ShaderPreprocessorError,
+        shader_file: PathBuf,
+    },
+
+    #[error("Shader source path has no parent")]
+    SourcePathHasNoParent,
+}
-- 
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