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use std::collections::hash_map::DefaultHasher;
use std::fs::read_to_string;
use std::hash::{Hash, Hasher};
use std::path::{Path, PathBuf};
use ecs::Component;
use crate::opengl::glsl::{
preprocess as glsl_preprocess,
PreprocessingError as GlslPreprocessingError,
};
const VERTEX_SHADER_FILE: &str = "vertex.glsl";
const FRAGMENT_SHADER_FILE: &str = "fragment.glsl";
const SHADER_DIR: &str = "engine";
/// Shader program
#[derive(Debug, Clone, PartialEq, Eq, Hash, Default, Component)]
pub struct Program
{
shaders: Vec<Shader>,
}
impl Program
{
/// Creates a new shader program with the default shaders.
///
/// # Errors
/// Returns `Err` if:
/// - Reading a default shader file Fails
/// - Preprocessing a shader fails.
pub fn new() -> Result<Self, Error>
{
let mut program = Self { shaders: Vec::new() };
program.push_shader(
Shader::read_shader_file(
Kind::Vertex,
&Path::new(SHADER_DIR).join(VERTEX_SHADER_FILE),
)?
.preprocess()?,
);
program.push_shader(
Shader::read_shader_file(
Kind::Fragment,
&Path::new(SHADER_DIR).join(FRAGMENT_SHADER_FILE),
)?
.preprocess()?,
);
Ok(program)
}
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 parent_dir = self
.file
.parent()
.ok_or(Error::SourcePathHasNoParent)?
.to_path_buf();
let source_preprocessed =
glsl_preprocess(self.source, &|path| std::fs::read(parent_dir.join(path)))
.map_err(|err| Error::PreprocessFailed {
source: err,
shader_file: self.file.clone(),
})?;
Ok(Self {
kind: self.kind,
source: source_preprocessed.into_owned(),
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: GlslPreprocessingError,
shader_file: PathBuf,
},
#[error("Shader source path has no parent")]
SourcePathHasNoParent,
}
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