Function project_main_segment 

pub fn project_main_segment(
    scene: &Scene,
    cuts: &[Range<usize>],
    options: RangeOptions,
    out: &mut Scene,
) -> RangeCut

Projects the main surface’s segment of scene — every command outside the overlay cuts (main_segment_ranges) — into out, through frust_engine::renderer::project_command_ranges: each gap between cuts is projected on its own, so its brackets are rebalanced (a clip open across a cut closes before it and reopens after it) and the concatenation is a well-nested display list. What SurfaceRenderer::encode_segmented keeps for the main surface.