Graphviz Generation
Understanding the dependency graph of a large engine codebase helps identify unwanted couplings, verify that layering rules are respected, and get new engineers oriented. GPBT can export the full target dependency graph as a Graphviz DOT file at the end of the configuration phase.
Enabling the export
Set GPBT_EXPORT_DEPENDENCY_GRAPH=ON at configure time:
cmake -S . -B build -DGPBT_EXPORT_DEPENDENCY_GRAPH=ON
After a successful configure, the DOT file is written to the path specified by GPBT_DEPENDENCY_GRAPH_FILE. The default is:
<cmake-binary-dir>/gpbt_dependency_graph.dot
To write it to a custom location:
cmake -S . -B build \
-DGPBT_EXPORT_DEPENDENCY_GRAPH=ON \
-DGPBT_DEPENDENCY_GRAPH_FILE=/path/to/graph.dot
Rendering the graph
Use the dot command from the Graphviz package to render the DOT file:
# Render as SVG
dot -Tsvg build/gpbt_dependency_graph.dot -o dependency_graph.svg
# Render as PNG
dot -Tpng build/gpbt_dependency_graph.dot -o dependency_graph.png
For large graphs, the fdp or sfdp layout engines tend to produce more readable results than the default dot hierarchical layout:
sfdp -Tsvg -Goverlap=prism build/gpbt_dependency_graph.dot -o dependency_graph.svg
Graph contents
The exported graph includes all registered GPBT targets and the dependency edges between them, labeled by visibility (PUBLIC, PRIVATE, INTERNAL, or DYNAMIC).
Thirdparty packages appear as terminal nodes, so you can see at a glance which engine modules depend on which external libraries.
Commit the rendered graph to your repository's documentation alongside this docs site. A static SVG embedded in a wiki page is often the fastest way for a new engineer to orient themselves in a large codebase.
Exporting only, not building
The dependency graph is written during the configuration phase, before any targets are compiled. You can get the graph without running a full build:
cmake -S . -B build -DGPBT_EXPORT_DEPENDENCY_GRAPH=ON
# The DOT file is written as soon as cmake finishes, no build step needed