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use gl;
use gl::types::*;
use std::ffi::CString;
use std::ptr::{null, null_mut};
type Result<A> = ::std::result::Result<A, StageError>;
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum Type {
TessellationControlShader,
TessellationEvaluationShader,
VertexShader,
GeometryShader,
FragmentShader
}
#[derive(Debug)]
pub struct Stage {
handle: GLuint,
ty: Type
}
impl Stage {
pub fn new(ty: Type, src: &str) -> Result<Self> {
unsafe {
let src = CString::new(glsl_pragma_src(src).as_bytes()).unwrap();
let handle = gl::CreateShader(opengl_shader_type(ty));
if handle == 0 {
return Err(StageError::CompilationFailed(ty, String::from("unable to create shader stage")));
}
gl::ShaderSource(handle, 1, [src.as_ptr()].as_ptr(), null());
gl::CompileShader(handle);
let mut compiled: GLint = gl::FALSE as GLint;
gl::GetShaderiv(handle, gl::COMPILE_STATUS, &mut compiled);
if compiled == (gl::TRUE as GLint) {
Ok(Stage {
handle: handle,
ty: ty
})
} else {
let mut log_len: GLint = 0;
gl::GetShaderiv(handle, gl::INFO_LOG_LENGTH, &mut log_len);
let mut log: Vec<u8> = Vec::with_capacity(log_len as usize);
gl::GetShaderInfoLog(handle, log_len, null_mut(), log.as_mut_ptr() as *mut GLchar);
gl::DeleteShader(handle);
log.set_len(log_len as usize);
Err(StageError::CompilationFailed(ty, String::from_utf8(log).unwrap()))
}
}
}
#[inline]
pub unsafe fn handle(&self) -> GLuint {
self.handle
}
}
impl Drop for Stage {
fn drop(&mut self) {
unsafe { gl::DeleteShader(self.handle) }
}
}
#[derive(Clone, Debug)]
pub enum StageError {
CompilationFailed(Type, String),
UnsupportedType(Type)
}
fn glsl_pragma_src(src: &str) -> String {
let mut pragma = String::from(GLSL_PRAGMA);
pragma.push_str(src);
pragma
}
const GLSL_PRAGMA: &'static str = "\
#version 330 core\n\
#extension GL_ARB_separate_shader_objects : require\n";
fn opengl_shader_type(t: Type) -> GLenum {
match t {
Type::TessellationControlShader => gl::TESS_CONTROL_SHADER,
Type::TessellationEvaluationShader => gl::TESS_EVALUATION_SHADER,
Type::VertexShader => gl::VERTEX_SHADER,
Type::GeometryShader => gl::GEOMETRY_SHADER,
Type::FragmentShader => gl::FRAGMENT_SHADER
}
}