How to Build a Procedural Building in Blender

Procedural building generation in Blender allows you to create customizable, scalable 3D structures using a single node network. By leveraging Geometry Nodes, you can define base footprints, stack floors automatically, distribute modular wall and window assets, and generate unique architectural details. This guide covers the core workflow for constructing a flexible procedural building generator from scratch.

1. Prepare Modular Mesh Assets

Before assembling the node network, model individual modular components matching standardized dimensions (e.g., 2m wide by 3m tall):

  • Wall Segment: A standard solid wall.
  • Window Segment: A wall module containing a window frame.
  • Door Segment: An entrance module for the ground floor.
  • Corner Segment: A corner pillar or specialized edge piece.
  • Roof Element: A flat roof cap or decorative trim piece.

Place these modular pieces into a dedicated Blender Collection named Building_Modules. Ensure all origins are centered at the bottom of each mesh.

2. Set Up the Floor Stack

  1. Create a new default object (e.g., a Plane or Cube), open the Geometry Nodes workspace, and assign a new node tree.
  2. Add a Mesh Line node to define the vertical distribution of floors.
  3. Connect an Integer input from the Group Input node into the Count input of the Mesh Line (rename it to Floor Count).
  4. Multiply the Floor Count by the standardized floor height (e.g., 3.0m) using a Vector Math (Multiply) or Combine XYZ node into the Offset input to establish correct vertical spacing.

3. Generate the Building Perimeter

  1. Create the building's base footprint using a Curve Rectangle node.
  2. Expose the X and Y dimensions to the Group Input as Width and Length.
  3. Use a Resample Curve node set to Length mode with a value matching your module width (e.g., 2.0m). This generates evenly spaced points along the perimeter for instancing walls.
  4. Pass the curve through a Curve to Points node to ensure proper normal orientation along the curve tangents.

4. Instance Walls and Floors

  1. Combine the vertical Mesh Line and horizontal perimeter points using a Mesh Line connected to a Duplicate Elements node, or duplicate the perimeter points along the Z-axis for each floor level using Instance on Points.
  2. Add a Collection Info node referencing your Building_Modules collection. Check Separate Children and Reset Children.
  3. Feed the collection geometry into the Instance input of an Instance on Points node, using your distributed perimeter points as the target.
  4. Align the instances to the curve tangents using an Align Euler to Vector node connected to the Rotation socket. Set the vector to the curve Tangent or point Normal.

5. Separate Ground Floor and Upper Floors

To ensure doors only appear on the ground level and standard windows appear on upper levels:

  1. Add an Index node and a Math (Compare/Equal) node to isolate floor level 0 (Z position or vertical index).
  2. Use a Separate Geometry node or a Switch node driven by this boolean condition.
  3. Route entrance modules to the points on the ground floor and randomized window/wall modules to the remaining upper floors.

6. Generate the Roof

  1. Capture the top-most points of the building using an Index or Position comparison matched to the maximum floor height.
  2. Use a Fill Curve node on the top perimeter curve to create a flat ceiling surface.
  3. Add an Extrude Mesh node to give the roof depth, or use an Instance on Points node to place a dedicated roof trim asset along the top boundary.

7. Expose Parameters to the Modifier

Connect key control sockets to the Group Input node to control the generator from the Modifier panel:

  • Floor Count: Controls building height.
  • Building Width / Length: Controls base footprint dimensions.
  • Random Seed: Drives variation across window and wall module distribution using a Random Value node plugged into the Instance Index of the module picker.
  • Roof Height / Inset: Fine-tunes roof extrusion and borders.