Crate glium

Expand description

Easy-to-use, high-level, OpenGL3+ wrapper.

Glium is based on glutin - a cross-platform crate for building an OpenGL window and handling application events.

Glium provides a Display which uses glutin for the Window and its associated GL Context.

§Initialization

The initialisation of a simple glium display occurs in two steps.

extern crate glium;
// Use the re-exported winit dependency to avoid version mismatches.
// Requires the `simple_window_builder` feature.
use glium::winit;

fn main() {
    // 1. The **winit::EventLoop** for handling events.
    let event_loop = winit::event_loop::EventLoopBuilder::new().build().unwrap();
    // 2. Create a glutin context and glium Display
    let (window, display) = glium::backend::glutin::SimpleWindowBuilder::new().build(&event_loop);
}

The display object is the most important object of this library and is used when you build buffers, textures, etc. and when you draw.

You can clone it and pass it around. However it doesn’t implement the Send and Sync traits, meaning that you can’t pass it to another thread.

The display has ownership of both the window and context, and also provides some methods related to domains such as events handling.

§Overview

OpenGL is similar to drawing software: you draw something, then draw over it, then over it again, etc. until you are satisfied of the result.

Once you have a display, you can call let mut frame = display.draw(); to start drawing. This frame object implements the Surface trait and provides some functions such as clear_color, but also allows you to draw with the rendering pipeline.

In order to draw something, you will need to pass:

A source of vertices (see the vertex module)
A source of indices (see the index module)
A program that contains the shader that the GPU will execute (see the program module)
A list of uniforms for the program (see the uniforms module)
Draw parameters to customize the drawing process (see the draw_parameters module)

Once you have finished drawing, you can call frame.finish() to swap buffers and present the result to the user.

§OpenGL equivalents in glium

Bind points: Glium automatically binds and unbinds buffers, textures, etc. in an optimized way.
Buffers: Buffers are strongly typed and can be used through vertex::VertexBuffer, index::IndexBuffer or uniforms::UniformBuffer.
Debug output: If you compile in debug mode, glium registers a debug output callback and panics if an OpenGL error happens.
Framebuffer Objects: FBOs are automatically managed by glium and are stored in the Context object. You can specify the attachments that you wish with the framebuffer module.
Instancing: Instancing is done either by passing a vertex::EmptyInstanceAttributes marker or one or several references to vertex buffers wrapped inside a PerInstance struct. See the vertex module for more infos.
Memory barriers: Calling glMemoryBarrier is automatically handled by glium, however you still need to call memoryBarrier() in your GLSL code in some situations.
Programs: See the program module.
Query objects: The corresponding structs are in the draw_parameters module. They are passed as draw parameters.
Renderbuffer: See the framebuffer module.
Render to texture: If you just want to draw on a texture, you can call texture.as_surface(). For more advanced options, see the framebuffer module.
Samplers: Samplers are automatically managed by glium and are stored in the Context object. You can specify how a texture should be sampled by using a Sampler dummy object in the uniforms module.
Shaders: You can’t manually create individual shaders. Instead you must create whole programs at once.
Textures: Textures are strongly typed and are found in the texture module.
Uniform blocks: If your program uses uniform blocks, you must pass a reference to a uniform buffer for the name of the block when drawing.
Vertex array objects: VAOs are automatically managed by glium if the backend supports them.

Re-exports§

pub use crate::draw_parameters::Blend;
pub use crate::draw_parameters::BlendingFunction;
pub use crate::draw_parameters::LinearBlendingFactor;
pub use crate::draw_parameters::BackfaceCullingMode;
pub use crate::draw_parameters::Depth;
pub use crate::draw_parameters::DepthTest;
pub use crate::draw_parameters::PolygonMode;
pub use crate::draw_parameters::DrawParameters;
pub use crate::draw_parameters::StencilTest;
pub use crate::draw_parameters::StencilOperation;
pub use crate::draw_parameters::Smooth;
pub use crate::index::IndexBuffer;
pub use crate::vertex::VertexBuffer;
pub use crate::vertex::Vertex;
pub use crate::vertex::VertexFormat;
pub use crate::program::Program;
pub use crate::program::ProgramCreationError;
pub use crate::program::ProgramCreationError::CompilationError;
pub use crate::program::ProgramCreationError::LinkingError;
pub use crate::program::ProgramCreationError::ShaderTypeNotSupported;
pub use crate::texture::Texture2d;
pub use crate::backend::glutin::Display;
pub use crate::backend::glutin::glutin;
pub use crate::backend::winit;

Modules§

backend: The backend module allows one to link between glium and the OpenGL context..
buffer: A buffer is a memory location accessible to the video card.
debug
draw_parameters: Describes miscellaneous parameters to be used when drawing.
field: Field utils
framebuffer: Framebuffers allow you to customize the color, depth and stencil buffers you will draw on.
index: In order to draw, you need to provide a way for the video card to know how to link primitives together.
memory_object: Contains everything related to external API memory objects.
pixel_bufferDeprecated: Moved to the texture module.
program: Items related to creating an OpenGL program.
semaphore: Contains everything related to external API semaphores.
texture: A texture is an image loaded in video memory, which can be sampled in your shaders.
uniforms: A uniform is a global variable in your program. In order to draw something, you will need to give glium the values of all your uniforms. Objects that implement the Uniform trait are here to do that.
vertex: Contains everything related to vertex sources.

Macros§

assert_no_gl_error: Calls the assert_no_error method on a glium::Display instance with file and line number information.
dynamic_uniform: Returns a Dynamic Uniforms Container to which values can be added later.
field: A macro to create a Field.
implement_buffer_content: Implements the glium::buffer::Content trait for the given type.
implement_uniform_block: Implements the glium::uniforms::UniformBlock trait for the given type.
implement_vertex: Implements the glium::vertex::Vertex trait for the given type.
program: Builds a program depending on the GLSL version supported by the backend.
uniform: Returns an implementation-defined type which implements the Uniform trait.

Structs§

BlitMask: Mask specifying, which kinds of buffers to copy when blitting between two frame buffers.
BlitTarget: Area of a surface in pixels. Similar to a Rect except that dimensions can be negative.
Capabilities: Represents the capabilities of the context.
ExtensionsList: Contains data about the list of extensions.
Frame: Implementation of Surface, targeting the default framebuffer.
IncompatibleOpenGl: Returned during Context creation if the OpenGL implementation is too old.
LinearSyncFence: Prototype for a SyncFence.
Rect: Area of a surface in pixels.
SyncFence: Provides a way to wait for a server-side operation to be finished.
Version: Describes a version.

Enums§

Api: Describes an OpenGL-related API.
DrawError: Error that can happen while drawing.
Handle: Handle to a shader or a program.
Profile: Describes the OpenGL context profile.
RawUniformValue: A raw value of a uniform. “Raw” means that it’s passed directly with glUniform. Textures for example are just passed as integers.
ReadError: Error that can happen while reading.
SwapBuffersError: Error that can happen when swapping buffers.
UuidError: Describes an error preventing the retrieval of the uuid.

Traits§

CapabilitiesSource: Trait for objects that describe the capabilities of an OpenGL backend.
GlObject: Trait for objects that are OpenGL objects.
Surface: Object that can be drawn upon.

Functions§

get_supported_glsl_version: Given an API version, this function returns the GLSL version that the implementation is required to support.

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