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.)

Modules

blend

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

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 Definitions

ElementBuffer	A buffer to store the indices that make up the geometry elements
VertexBuffer	A buffer to store the vertices on the GPU