Text & LaTeX pipeline

Murali has two text backends that share the same final step (texture quad), but differ significantly in how they produce the texture.

This page is about the specialized text pipelines after the broader projection and backend architecture is already understood.

Label (glyph atlas)

Label uses fontdue for CPU-side glyph rasterization.

The pipeline:

1. LabelResources is initialized once and holds the font + a glyph atlas texture
2. layout_label computes glyph positions and UVs for the given string and world height
3. build_label_mesh produces a Mesh with one quad per glyph, sampling from the atlas
4. The atlas texture is uploaded once as a bind group and reused for all labels

The atlas is a single RGBA texture. All glyphs share it, so multiple labels in a scene use the same bind group — efficient for the GPU.

Labels are best for short strings, numbers, and axis annotations where you don't need math typesetting.

LaTeX

LaTeX uses an external latex + dvisvgm toolchain to compile expressions to SVG, then rasterizes to RGBA.

The pipeline:

1. compile_latex(source, cache_dir) — shells out to latex + dvisvgm, caches the SVG to disk in a temp directory keyed by source hash
2. rasterize_svg — uses resvg + tiny-skia to render the SVG to RGBA at a resolution derived from the viewport height
3. The RGBA is uploaded as a texture and rendered as a single textured quad
4. normalized_world_height computes the quad's world-space dimensions from the raster metrics

The disk cache means repeated renders of the same expression are fast — only the first compile is slow.

Requires latex and dvisvgm to be installed on the system. Use murali doctor to check.

Typst (default math backend)

Typst is the preferred math backend. It's embedded directly in the binary — no external tools required.

The pipeline:

1. TypstBackend::render_to_svg(source, pt_size) — compiles Typst markup to SVG in-process
2. rasterize_svg_to_rgba — same resvg rasterizer as LaTeX
3. The result is cached in an LRU cache (TypstRasterCache, capacity 128) keyed by "{height}::{source}"
4. Uploaded as a texture quad, same as LaTeX

The LRU cache means frequently used expressions (axis labels, repeated formulas) are only rasterized once per session.

The scale factor for rasterization is clamped between 1× and 8× based on the viewport height and the requested world height, keeping texture resolution reasonable.

Shared final step

Both LaTeX and Typst end up calling build_textured_quad:

fn build_textured_quad(
    raster_width: u32,
    raster_height: u32,
    world_height: f32,
    color: Vec4,
) -> Mesh

This produces a rectangle with the correct aspect ratio in world space. The color is multiplied in the fragment shader, so you can tint expressions.

What This Page Owns

This page is the home for:

• label text via glyph atlas
• LaTeX raster pipeline
• Typst raster pipeline
• the shared textured-quad final step

For the more general rendering pipeline, see Projection and Renderer.