Edifice

Buildings, written as grammars.

You write rules saying how a face breaks down — floors, then rooms, then window strips — and the engine derives the geometry from that. Edifice implements a split grammar, a subset of shape grammars in the Wonka 2003 / CGA-shape tradition: the central operator is split(axis, pcts) { ChildRule* }, which carves a face along an axis at explicit per-cut percentages and dispatches a named rule for each piece. Pieces inherit the parent shape, so rules compose recursively.

Three primitive types: box for cubes, gable for pitched roofs (5 faces, ridge along Z), and hip for 4-sided pyramid roofs along the longer footprint axis. Roof faces are colorable and texturable but not splittable — their triangular ends would degenerate.

From text source to rendered geometry.

The pipeline runs end-to-end inside the app. A Flex lexer and Bison parser (regenerated on every build) compile DSL source to an AST in Ast.h. A tree-walking interpreter executes the AST, maintaining a rule registry and an implicit "current shape" stack, and lowering grammar features down to the Building::* primitive layer. The geometry that comes out drives a Qt 5 viewport on an OpenGL 4.1 core profile context with 4× MSAA, an orbit camera, and frame-locked WASD pan.

The CodeEditor dock re-parses and re-renders as you type. Auto-render is debounced at 900 ms, with an immediate render on cursor-line-change or Enter. Sit on a broken line for 2.5 s and a non-modal red banner explains the syntax error without interrupting the edit. AST diff plus checkpointed snapshots make incremental edits cheap.

Three demo scenes.

skyline.txt Two rows of five city towers along a street with sidewalks, lamp posts, and lane markings. The auto-loaded scene at app start.

cityCenter.txt Tiered central skyscraper with cantilevered balconies, ringed by four corner towers on a raised plaza.

searsTower_textured.txt 9-block bundled-tube geometry rendered through the texture pipeline rather than the windowed-strip grammar.

The pieces underneath.

• Custom DSL with Flex/Bison parser
• Tree-walking interpreter with rule registry & shape stack
• Live in-editor reparse, debounced at 900 ms
• 3D viewer: Qt 5, OpenGL 4.1 core, 4× MSAA, orbit camera
• Procedural texture catalog on a GL_TEXTURE_2D_ARRAY
• Wavefront OBJ export with per-vertex color extension
• Loading panel with chunked GPU upload progress
• Three primitive types: box, gable, hip
• Bundled scripts library: skyline, city center, Sears, houses

C++, Qt 5, OpenGL 4.1, Flex/Bison, GLM, stb_image. Visual Studio on Windows, with win_flex and win_bison vendored at tools/winflexbison/ so the parser regenerates on every build with no separate install.

Edifice grew out of an earlier 3D building project I worked on with Zachariah Menzie. About 14% of the code — mostly the block-geometry core in Building.{cpp,hpp} and BuildingBlock.{cpp,h} — is Zach's original authorship, and everything Edifice does still rests on top of it. The DSL, the interpreter, the shape-grammar layer, the live editor, the texture pipeline, the orbit camera, and the procedural texture and script tooling were all written for this rewrite.

Thank you, Zach. You were a great partner on the original, and Edifice doesn't exist without the work we did together.