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//! Exposes the OpenGL [`Shader`](struct.Shader.html) object and related types. use std::marker::PhantomData; use std::ptr; use gl; use gl::types::*; use context::{AContext, BaseContext}; use types::{GLObject, GLError}; /// An OpenGL shader object. /// /// A shader is a small program that runs on the GPU to compute a part of /// the rendering pipeline. There are two shaders that are necessary for /// rendering in OpenGL: the vertex shader and the fragment shader. The /// vertex shader translates geometry from world space into screen space, and /// the fragment shader determines the final color of each pixel (or /// 'fragment'). In order to use a shader, it should be linked with /// a [`Program`](../program/struct.Program.html) to be used for drawing. /// /// A shader will automatically be deleted after going out of scope. /// /// # See also /// [`gl.build_fragment_shader`](trait.ContextShaderBuilderExt.html#tymethod.build_fragment_shader), /// [`gl.build_vertex_shader`](trait.ContextShaderBuilderExt.html#tymethod.build_vertex_shader), /// and [`gl.build_shader`](trait.ContextShaderBuilderExt.html#tymethod.build_shader): /// Build and compile a new shader object. /// /// [`gl.create_shader`](trait.ContextShaderExt.html#method.create_shader): /// Create a new, empty shader object. pub struct Shader { gl_id: GLuint, _phantom: PhantomData<*mut ()> } impl Drop for Shader { fn drop(&mut self) { unsafe { gl::DeleteShader(self.gl_id); } } } impl GLObject for Shader { type Id = GLuint; unsafe fn from_raw(id: Self::Id) -> Self { Shader { gl_id: id, _phantom: PhantomData } } fn id(&self) -> Self::Id { self.gl_id } } unsafe fn _get_shader_iv(shader: &Shader, pname: GLenum, params: *mut GLint) { gl::GetShaderiv(shader.id(), pname, params); dbg_gl_sanity_check! { GLError::InvalidEnum => "`pname` is not an accepted value", GLError::InvalidValue => "`shader` is not a value generated by OpenGL", GLError::InvalidOperation => "`shader` is not a shader object, or `pname` is GL_COMPILE_STATUS, GL_INFO_LOG_LENGTH or GL_SHADER_SOURCE_LENGTH but a shader compiler is not supported", _ => "Unknown error" } } /// A safe interface for creating a shader with a source, and returning an error /// or panicking if there is an error. pub struct ShaderBuilder<'a, C: 'a> where C: AContext { gl: &'a C, ty: ShaderType, source: &'a str } impl<'a, C: 'a> ShaderBuilder<'a, C> where C: AContext { fn new(gl: &'a C, ty: ShaderType, source: &'a str) -> Self { ShaderBuilder { gl: gl, ty: ty, source: source } } /// Try to compile a shader with the provided options, or `Err` if /// a new shader object could not be created or if there was an error /// compiling the provided source. pub fn try_unwrap(self) -> Result<Shader, GLError> { unsafe { let mut shader = try! { self.gl.create_shader(self.ty).or_else(|_| { let msg = "Error creating OpenGL shader"; Err(GLError::Message(msg.to_owned())) }) }; self.gl.shader_source(&mut shader, self.source); try!(self.gl.compile_shader(&mut shader)); Ok(shader) } } /// Try to compile a shader with the provided options, panicking if /// a new shader object could not be created or if there was an error /// compiling the provided source. pub fn unwrap(self) -> Shader { self.try_unwrap().unwrap() } } /// An extension trait for [`ContextOf`](../context/struct.ContextOf.html) that /// adds functions to build shaders using the [`ShaderBuilder`] /// (struct.ShaderBuilder.html) interface. pub trait ContextShaderBuilderExt: AContext + Sized { /// Build a new shader with the provided shader type and shader source. /// /// # Example /// ```no_run /// #[macro_use] extern crate glitter; /// use glitter::prelude::*; /// /// # fn main() { /// let vertex_source = r##"#version 100 /// attribute vec4 position; /// /// void main() { /// gl_Position = position; /// _color = color; /// } /// "##; /// /// let gl = unsafe { glitter::Context::current_context() }; /// let shader = gl.build_shader(glitter::VERTEX_SHADER, vertex_source).unwrap(); /// # } /// ``` fn build_shader<'a>(&'a self, ty: ShaderType, source: &'a str) -> ShaderBuilder<'a, Self>; /// Build a new fragment shader with the provided shader source. /// /// # Example /// ```no_run /// #[macro_use] extern crate glitter; /// use glitter::prelude::*; /// /// # fn main() { /// let fragment_source = r##"#version 100 /// void main() { /// gl_FragColor = vec4(1.0, 0.0, 0.0, 0.0); /// } /// "##; /// /// let gl = unsafe { glitter::Context::current_context() }; /// let shader = gl.build_fragment_shader(fragment_source).unwrap(); /// # } /// ``` fn build_fragment_shader<'a>(&'a self, source: &'a str) -> ShaderBuilder<'a, Self> { self.build_shader(ShaderType::FragmentShader, source) } /// Build a new vertex shader with the provided shader source. /// /// # Example /// ```no_run /// #[macro_use] extern crate glitter; /// use glitter::prelude::*; /// /// # fn main() { /// let vertex_source = r##"#version 100 /// attribute vec4 position; /// /// void main() { /// gl_Position = position; /// _color = color; /// } /// "##; /// /// let gl = unsafe { glitter::Context::current_context() }; /// let shader = gl.build_vertex_shader(vertex_source).unwrap(); /// # } /// ``` fn build_vertex_shader<'a>(&'a self, source: &'a str) -> ShaderBuilder<'a, Self> { self.build_shader(ShaderType::VertexShader, source) } } impl<C: AContext> ContextShaderBuilderExt for C { fn build_shader<'a>(&'a self, ty: ShaderType, source: &'a str) -> ShaderBuilder<'a, C> { ShaderBuilder::new(self, ty, source) } } /// An extension trait that includes shader-related OpenGL methods. pub trait ContextShaderExt: BaseContext { /// Create a new, uninitialized shader. /// /// # Safety /// Most OpenGL functions that take a shader expect the shader to have /// been setup and compiled already. Before using this shader, /// it must have its source set using [`gl.shader_source`] /// (trait.ContextShaderExt.html#method.shader_source) and compiled with /// [`gl.compile_shader`](trait.ContextShaderExt.html#method.compile_shader). /// Instead, consider using one of the shader builder functions, which /// handle proper setup and compilation automatically. /// /// # Example /// ```no_run /// #[macro_use] extern crate glitter; /// use glitter::prelude::*; /// /// # fn main() { /// let gl = unsafe { glitter::Context::current_context() }; /// let vertex_source = r##"#version 100 /// attribute vec4 position; /// /// void main() { /// gl_Position = position; /// } /// "##; /// /// let shader = unsafe { /// let mut shader = gl.create_shader(glitter::VERTEX_SHADER).unwrap(); /// gl.shader_source(&mut shader, vertex_source); /// gl.compile_shader(&mut shader).unwrap(); /// /// shader /// }; /// # } /// ``` /// /// # See also /// [`gl.build_shader`](trait.ContextShaderBuilderExt.html#tymethod.build_shader), /// [`gl.build_vertex_shader`](trait.ContextShaderBuilderExt.html#method.build_vertex_shader), /// and [`gl.build_fragment_shader`](trait.ContextShaderBuilderExt.html#method.build_fragment_shader): /// A safe interface for creating and building shaders, which automatically /// handle compilation and error checking. /// /// [`glCreateShader`](http://docs.gl/es2/glCreateShader) OpenGL docs unsafe fn create_shader(&self, shader_type: ShaderType) -> Result<Shader, ()> { let id = gl::CreateShader(shader_type.gl_enum()); dbg_gl_sanity_check! { GLError::InvalidEnum => "`shaderType` is not an accepted value", _ => "Unknown error" } if id > 0 { Ok(Shader::from_raw(id)) } else { Err(()) } } /// Set or replace a shader object's source. The shader should be recompiled /// after calling this function by using the [`gl.compile_shader`] /// (trait.ContextShaderExt.html#method.compile_shader) function /// /// # See also /// [`gl.create_shader`](trait.ContextShaderExt.html#method.create_shader): /// A function to create a new, uninitialized shader. Includes an example /// of how to use `gl.shader_source` /// /// [`gl.build_shader`](trait.ContextShaderBuilderExt.html#tymethod.build_shader), /// [`gl.build_vertex_shader`](trait.ContextShaderBuilderExt.html#method.build_vertex_shader), /// and [`gl.build_fragment_shader`](trait.ContextShaderBuilderExt.html#method.build_fragment_shader): /// The preferred way to create and compile a shader object, which skips /// the need to directly call `gl.shader_source`. /// /// [`glShaderSource`](http://docs.gl/es2/glShaderSource) OpenGL docs fn shader_source(&self, shader: &mut Shader, source: &str) { unsafe { let source_ptr = source.as_ptr() as *const GLchar; let source_len = source.len() as GLint; gl::ShaderSource(shader.id(), 1, &source_ptr as *const *const GLchar, &source_len as *const GLint); dbg_gl_error! { GLError::InvalidOperation => "`shader` is not a shader object or shader compiler is not supported", GLError::InvalidValue => "`shader` is not a value generated by OpenGL or `count` < 0", _ => "Unknown error" } } } /// Compile the shader's associated source. /// /// # Panics /// This function will panic if an OpenGL error occurs while trying to /// compile the shader (determined by calling [`gl.get_error`] /// (../context/struct.ContextOf.html#method.get_error)). Note that this /// function ***does not*** panic if there was an error *within* the shader; /// this function should only panic if the shader is invalid or if /// shader compilation is unavailable with the current OpenGL context. /// /// # Failures /// If a compilation error occurs, an `Err` value will be returned /// with the compilation error messages (as determined by /// [`gl.get_shader_info_log`](trait.ContextShaderExt.html#method.get_shader_info_log)). /// /// # See also /// [`gl.create_shader`](trait.ContextShaderExt.html#method.create_shader): /// A function to create a new, uninitialized shader. Includes an example /// of how to use `gl.compile_shader` /// /// [`gl.build_shader`](trait.ContextShaderBuilderExt.html#tymethod.build_shader), /// [`gl.build_vertex_shader`](trait.ContextShaderBuilderExt.html#method.build_vertex_shader), /// and [`gl.build_fragment_shader`](trait.ContextShaderBuilderExt.html#method.build_fragment_shader): /// The preferred way to create and compile a shader object, which skips /// the need to directly call `gl.compile_shader`. /// /// [`glCompileShader`](http://docs.gl/es2/glCompileShader) OpenGL docs fn compile_shader(&self, shader: &mut Shader) -> Result<(), GLError> { let success = unsafe { gl::CompileShader(shader.id()); dbg_gl_error! { GLError::InvalidOperation => "`shader` is not a shader object or shader compiler is not supported", GLError::InvalidValue => "`shader` is not a value generated by OpenGL", _ => "Unknown error" } let mut compile_status : GLint = 0; _get_shader_iv(shader, gl::COMPILE_STATUS, &mut compile_status as *mut GLint); compile_status == gl::TRUE as GLint }; if success { Ok(()) } else { let msg = match self.get_shader_info_log(&shader) { Some(s) => { s }, None => { String::from("[Unknown shader error]") } }; Err(GLError::Message(msg)) } } /// Get the information log associated with a shader. This is used to /// get compilation errors, warnings, or other diagnostic information /// that may have occurred while trying to compile a shader. Returns `None` /// if no such diagnostic information was generated. /// /// # Example /// ```no_run /// #[macro_use] extern crate glitter; /// use glitter::prelude::*; /// /// # fn main() { /// let fragment_source = r##"#version 100 /// void main() { /// float someValue = 1.0 * 2.0; /// gl_FragColor = vec4(1.0, 0.0, 0.0, 0.0); /// } /// "##; /// /// let gl = unsafe { glitter::Context::current_context() }; /// let shader = gl.build_fragment_shader(fragment_source).unwrap(); /// if let Some(info) = gl.get_shader_info_log(&shader) { /// println!("Shader compilation info: {}", info); /// // "Shader compilation info: unused variable `someValue` on line 3" /// // (or whatever other diagnostics your graphics device /// // decides to output) /// } /// # } /// ``` /// /// # See also /// [`glGetShaderInfoLog`](http://docs.gl/es2/glGetShaderInfoLog) OpenGL docs fn get_shader_info_log(&self, shader: &Shader) -> Option<String> { unsafe { let mut info_length : GLint = 0; _get_shader_iv(shader, gl::INFO_LOG_LENGTH, &mut info_length as *mut GLint); if info_length > 0 { let mut bytes = Vec::<u8>::with_capacity(info_length as usize); gl::GetShaderInfoLog(shader.id(), info_length, ptr::null_mut(), bytes.as_mut_ptr() as *mut GLchar); dbg_gl_sanity_check! { GLError::InvalidValue => "`shader` is not a value generated by OpenGL, or `maxLength` < 0", GLError::InvalidOperation => "`shader` is not a shader object", _ => "Unknown error" } bytes.set_len((info_length - 1) as usize); String::from_utf8(bytes).ok() } else { None } } } } impl<C: BaseContext> ContextShaderExt for C { } gl_enum! { /// The possible types of shader objects. pub gl_enum ShaderType { /// A shader that is used for processing per-vertex data. pub const VertexShader as VERTEX_SHADER = gl::VERTEX_SHADER, /// A shader that is used for processing per-fragment (per-pixel) /// data. pub const FragmentShader as FRAGMENT_SHADER = gl::FRAGMENT_SHADER } }