Crate azul_glium

source ·
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 extends the glutin::GlWindow with a high-level, safe API.

Initialization

The initialisation of a glium display occurs in several steps.

extern crate glium;

fn main() {
    // 1. The **winit::EventsLoop** for handling events.
    let mut events_loop = glium::glutin::EventsLoop::new();
    // 2. Parameters for building the Window.
    let window = glium::glutin::WindowBuilder::new()
        .with_dimensions(1024, 768)
        .with_title("Hello world");
    // 3. Parameters for building the OpenGL context.
    let context = glium::glutin::ContextBuilder::new();
    // 4. Build the Display with the given window and OpenGL context parameters and register the
    //    window with the events_loop.
    let display = glium::Display::new(window, context, &events_loop).unwrap();
}

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 a 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 backend::glutin::glutin;
pub use draw_parameters::BackfaceCullingMode;
pub use draw_parameters::PolygonMode;
pub use draw_parameters::DrawParameters;
pub use draw_parameters::Smooth;
pub use vertex::Vertex;
pub use program::ProgramCreationError;
pub use program::ProgramCreationError::CompilationError;
pub use program::ProgramCreationError::LinkingError;
pub use program::ProgramCreationError::ShaderTypeNotSupported;
pub use texture::Texture2d;
pub use backend::glutin::Display;

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.
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.
pixel_buffer
DEPRECATED. Moved to the texture module.
program
Items related to creating an OpenGL program.
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.
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

Blend
Blend effect that the GPU will use for blending.
BlitTarget
Area of a surface in pixels. Similar to a Rect except that dimensions can be negative.
Depth
Represents the depth parameters of a draw command.
Frame
Implementation of Surface, targeting the default framebuffer.
IncompatibleOpenGl
Returned during Context creation if the OpenGL implementation is too old.
IndexBuffer
A list of indices loaded in the graphics card’s memory.
LinearSyncFence
Prototype for a SyncFence.
Program
A combination of shaders linked together.
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.
VertexBuffer
A list of vertices loaded in the graphics card’s memory.

Enums

Api
Describes an OpenGL-related API.
BlendingFunction
Function that the GPU will use for blending.
DepthTest
The function that the GPU will use to determine whether to write over an existing pixel on the target.
DrawError
Error that can happen while drawing.
Handle
Handle to a shader or a program.
LinearBlendingFactor
Indicates which value to multiply each component with.
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.
StencilOperation
Specificies which operation the GPU will do depending on the result of the stencil test.
StencilTest
Specifies which comparison the GPU will do to determine whether a sample passes the stencil test. The general equation is (ref & mask) CMP (stencil & mask), where ref is the reference value (stencil_reference_value_clockwise or stencil_reference_value_counter_clockwise), CMP is the comparison chosen, and stencil is the current value in the stencil buffer.
SwapBuffersError
Error that can happen when swapping buffers.

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.

Type Definitions

VertexFormat
Describes the layout of each vertex in a vertex buffer.