Crate golem

golem is an opinionated mostly-safe graphics API

When possible, golem should make simple things safe (bind objects before acting on them, or check if they’re bound for objects that are expensive to bind.) However, when not possible or convenient (bounds checking the indices in an element buffer, for example), golem provides unsafe APIs with well-defined safety conditions.

A minimal example to display a triangle:

let vertices = [
    // Position         Color
    -0.5, -0.5,         1.0, 0.0, 0.0, 1.0,
    0.5, -0.5,          0.0, 1.0, 0.0, 1.0,
    0.0, 0.5,           0.0, 0.0, 1.0, 1.0
];
let indices = [0, 1, 2];

let mut shader = ShaderProgram::new(
    ctx,
    ShaderDescription {
        vertex_input: &[
            Attribute::new("vert_position", AttributeType::Vector(D2)),
            Attribute::new("vert_color", AttributeType::Vector(D4)),
        ],
        fragment_input: &[Attribute::new("frag_color", AttributeType::Vector(D4))],
        uniforms: &[],
        vertex_shader: r#" void main() {
        gl_Position = vec4(vert_position, 0, 1);
        frag_color = vert_color;
    }"#,
        fragment_shader: r#" void main() {
        gl_FragColor = frag_color;
    }"#,
    },
)?;

let mut vb = VertexBuffer::new(ctx)?;
let mut eb = ElementBuffer::new(ctx)?;
vb.set_data(&vertices);
eb.set_data(&indices);
shader.bind();

ctx.clear();
unsafe {
    shader.draw(&vb, &eb, 0..indices.len(), GeometryMode::Triangles)?;
}

The core type of golem is the Context, which is constructed from the glow Context. From the Context, ShaderPrograms are created, which take in data from Buffers. Once the data is uploaded to the GPU via Buffer::set_data, it can be drawn via ShaderProgram::draw.

Initializing

The user is responsible for windowing and providing a valid glow Context to create a Context. You can try out the blinds crate, which works well with golem, but using winit directly or other windowing solutions like sdl2 are also options.

OpenGL Versions

It currently is implemented via glow, and it targets OpenGL 3.2 on desktop and WebGL 1 (so it should run on a wide range of hardware.) GL 3.2 is selected for maximum desktop availability, and WebGL 1 is available on 97% of clients to WebGL’s 75% (taken from caniuse.com at time of writing.)

Re-exports

pub use glow;

Modules

blend

Various options to specify how to combine pixels with what they draw over

depth

Various options to specify the depth of view volume and how pixels are determined to occlude each other

Structs

Attribute

An input to a shader program stage

Buffer

A collection of values stored contiguously on the GPU, as either a VertexBuffer or an ElementBuffer

Context

The context required to interact with the GPU

ShaderDescription

The parameters to create a ShaderProgram

ShaderProgram

A GPU program that draws data to the screen

Surface

A framebuffer that allows render-to-texture

Texture

An image stored on the GPU

Uniform

A uniform value to pass in to the ShaderDescription

Enums

AttributeType

The data type of a given attribute

ColorFormat

How a pixel’s color is laid out in memory

Dimension

The dimensionality of a vector or matrix shader input

GeometryMode

The GeometryMode determines how the data is drawn during ShaderProgram::draw

GolemError

The library’s error conditions

NumberType

Used to determine whether shader uniforms are ints or floats

TextureFilter

How textures should scale when being drawn at non-native sizes

TextureWrap

How the texture should wrap if a sample is outside the edge

UniformType

The type of the uniform in GLSL

UniformValue

A value to provide to a uniform

Type Aliases

ElementBuffer

A buffer to store the indices that make up the geometry elements

VertexBuffer

A buffer to store the vertices on the GPU