How to generate building on surface

Question

I have created 20 towers.

Each tower contains few mesh. Each tower is not with single mesh. Some are curve some have array modifiers some bevel etc.

I want to generate on a plane to make a city. With single mesh we can. I have created collection to divide the building small medium and large.

I have created a generation result collection and in that 3 collection (small medium and large). In the small medium and large collection i have divide the collection in the name s1 s2 for each building.

I tried to parent each building with the base of plane. But all mess. All the parts of the building distributed here and there.

Any solution how can i fix all the building on single plan to make a city. Thanks

Answer 1

You could use particles and collections.

Start off by copying all of your buildings (and only your buildings) and paste them in one collection. Since Blender's particle system does not support rendering objects with their children (the multiple meshes per tower), you need to apply all modifiers and join the meshes that make one building together (of course all on the pasted buildings in the new collection). After doing that, place the origins of each new building to their bottoms so they go on top of the plane rather than halfway through the plane.

Select the plane that the city will be on and go to Properties > Particle Properties and add a new Particle System. Change the type to Hair. Each hair will represent one building. Go to Emission and play around with Number and Seed until you are happy with the positions and number of hairs.

To render each hair as a building, go to Render > Render As and change it to Collection. Now, go to Render > Collection > Instance Collection and set it to the building collection. If you want some buildings to appear more often than others, also check Use Count. More count for a building means it appears more often and vice versa. To change the size of the buildings, go to Render > Scale and tweak it.

NOTE: At the time of writing (June 2020, version 2.83), Blender's particle system cannot self-collide. This means that sometimes buildings will intersect with one another. As of now, the only way to get around this is to change the seed until no buildings intersect.

Answer 2

Blender 2.93+ has solved this with Geometry Nodes. The Point Instance node has a Collection option to instance a Whole Collection. You can easily instance a single collection with the following setup.

In addition, the Poisson Disk distribution method gives you the ability to specify a minimum distance between points to avoid self intersection.

At this point, I don't believe it's possible to make multiple point clouds communicate this information between them. If you want to instance multiple collections without intersections you'll have to create a custom attribute, randomize it, do some math comparison, and then you can use the Boolean value leftover as a Mask for a Point Separate node.

This should be able to be chained infinitely with the addition of one more attribute.

For a proof of concept I've created a third collection here, to be instanced between a random value of 2 and 1+.

Answer 3

I'm guessing here, but it seems you have buildings made with separate meshes and want to place each building as a complete whole, onto the plane?

If so you can make each building's component a "Child" of a parent, which could be an Empty. You then move that empty onto the plane and all of the building's components will stick together and follow.

You do the same for each building.

Once each (building) is on the plane, the plane itself can then act as a parent for all of the building-parents, i.e. make a city block which will stick together should you move the plane.

See this answer here -

Partial Rotation

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