Procedurally generated city!
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Procedurally generated by a shape grammar

For this project, I designed a shape grammar that creates urban buildings, and designed a city layout to place the buildings generated by my shape grammar. The overall result is a proceedurally generated city!

Shape Grammar Design

  • Shape Node: This is the basic building block for my grammar. A shape node knows its shape, its max height, its position/rotation/scale, its iteration number, and its color.
    • All transformations while performing the iterations are done directly to each shape node, and then finally rendered into the corresponded loaded geometry mesh by my renderer.
  • Grammar rules
Skyscrapers Apartments Parks
  • Skyscrapers

    • Skyscrapers grow non-deterministically, but with a greater probability than apartments.
    • Skyscrapers shrink non-deterministically, to mimic
  • Apartments

    • Apartments when first placed, subdivide into two components at right angles, to mimic the appearance of actual apartment buildings I have seen. The configuration of the two parts and the axis along which I subdivide is random.
    • Apartments also grow non-deterministically, but for equivalent max heights, an apartment's and a skyscraper's height will be controlled by the max height multiplied by a size ratio determined by the city design (i.e. apartment: 1.5, skyscraper: 4), so that they grow to approprate heights.
  • Parks

    • Parks generate trees.
    • Both the number and placement of trees within a park are non-deterministic.
  • Renderer: Parses the shape grammar by applying the rules for a given number of iterations. The result is a set of nodes for which the renderer finds the corresponding geometry and texture (loaded at the start), applies the node's transformations, and adds it to the scene.

City Layout Design

  • City configurability: I have written a city class so that each city has a city size, a block size, and a road size.
  • City Blocks
    • Blocks are placed according to city size, road size, and block size (set and easily changed by a city instance)
    • Block size is flexible: building placement adapts to the block size by scaling each building accordingly, so that there are no buildings unreachable in the middle of a block, and so that the block is filled length-wise like in actual cities.
    • Building choice: blocks are filled according to a shape ratio calculated by the block generator. For example, higher density blocks will have a higher ratio of skyscrapers to apartments.
    • Park blocks: in the real cities I have seen, parks usually fill up an entire block. Going off that, I decide block-wise whether there will be a park, and then fill the block with park nodes.
  • City density
    • In my layout design, I have equated city density with building height and building choice.
    • Buildings toward the center are more likely to be taller and fatter, and more likely to be skyscrapers
    • While high-level density is determined by a buildings location within the city (center or marginal), local density is calculated by a multi-octave noise function.


  • Shadows: the user can turn shadows on and off
  • Iteration number: the user can see how the buildings are placed and then subsequently grow
  • Rerendering: a rerender button has been included for easy regeneration
  • More to come!