Module nannou::ui::backend::glium::glium [−] [src]

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.

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.
glutin	The purpose of this library is to provide an OpenGL context on as many platforms as possible.
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.

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.
Display	A GL context combined with a facade for drawing upon.
DrawParameters	Represents the parameters to use when drawing.
Frame	Implementation of `Surface`, targeting the default framebuffer.
HeadlessRenderer	A headless glutin context.
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.
Texture2d	A two-dimensional texture containing floating-point data.
Version	Describes a version.
VertexBuffer	A list of vertices loaded in the graphics card's memory.

Enums

Api	Describes an OpenGL-related API.
BackfaceCullingMode	Describes how triangles should be filtered before the fragment processing. Backface culling is purely an optimization. If you don't know what this does, just use `CullingDisabled`.
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.
PolygonMode	Defines how the device should render polygons.
Profile	Describes the OpenGL context profile.
ProgramCreationError	Error that can be triggered when creating a `Program`.
RawUniformValue	A raw value of a uniform. "Raw" means that it's passed directly with `glUniform`. Textures for example are just passed as integers.
Smooth	Specifies a hint for the smoothing.
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.
Vertex	Trait for structures that represent a vertex.

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.