52 lines
1.7 KiB
Markdown
52 lines
1.7 KiB
Markdown
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# epiphany-graph-rs
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Hybrid graph layout for DAGs that still want to breathe.
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This crate treats Sugiyama as a constraint generator instead of a final layout.
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The Sugiyama pass assigns ranks and same-rank order; the force pass relaxes
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those constraints with springs, repulsion, collision, and edge direction
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pressure.
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The result is a spectrum:
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- force-dominant for organic structure
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- Sugiyama-dominant for hierarchical DAGs
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- hybrid for the usual graph reality, where purity gets mugged in the hallway
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## Current Pipeline
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1. Assign ranks from directed edges using a longest-path DAG pass.
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2. Preserve partial hierarchy for cyclic leftovers with local edge pressure.
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3. Order nodes inside each rank with repeated barycenter sweeps.
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4. Generate rank, order, and edge-direction constraints.
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5. Relax the graph with deterministic force iterations.
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## Example
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```rust
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use epiphany_graph_rs::{layout, Graph, LayoutConfig};
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let mut graph = Graph::new();
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let a = graph.add_node(1.0);
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let b = graph.add_node(1.0);
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let c = graph.add_node(1.0);
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graph.add_edge(a, b);
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graph.add_edge(b, c);
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let result = layout(&graph, &LayoutConfig::default());
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for node in result.nodes {
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println!("{:?}: ({}, {}) rank={}", node.id, node.x, node.y, node.rank);
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}
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```
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## Notes
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The first release favors a small deterministic core over a sprawling layout
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cathedral. The public API exposes generated constraints so callers can inspect,
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reuse, tune, or replace the force relaxation phase later.
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The current repulsion pass is exact pairwise repulsion. That is simple and
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stable for modest graphs; larger graphs should move toward a Barnes-Hut or grid
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approximation before pretending heroism is a scalability plan.
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