Vello Sparse Tests

This is a development-only crate for testing the sparse_strip renderers across a corpus of reference images:

• CPU
• WGPU
• WASM32 WebGL

The vello_test proc macro will create a snapshot test for each supported renderer target. See the below example usage.

// Draws a filled triangle into a 125x125 scene.
#[vello_test(width = 125, height = 125)]
fn filled_triangle(ctx: &mut impl Renderer) {
    let path = {
        let mut path = BezPath::new();
        path.move_to((5.0, 5.0));
        path.line_to((95.0, 50.0));
        path.line_to((5.0, 95.0));
        path.close_path();

        path
    };

    ctx.set_paint(LIME);
    ctx.fill_path(&path);
}

See all the attributes that can be passed to vello_test in vello_dev_macros/test.rs.

Testing WebGL on the Browser

Requirements:

• on MacOS, a minimum Clang major version of 20 is required.

To run the vello_sparse_tests suite including the WebGL tests:

wasm-pack test --headless --chrome --features webgl

To debug the output images in webgl, run the same command without --headless. Any tests that fail will have their diff image appended to the bottom of the page.