Road Intersection mesh generation

Hi guys,

For the last month I was learning about meshes and how procedurally generate them. For what I need it looks very straightforward.
For my little app I planning to have a road tool (very simple), user draws lines and curves and road is generated with specific width (flat).
So I can now create a drawing tool and generate simple mesh along the curve or line.
Next step is to be able to construct intersections...

I looked at lots of example but couldn't find any descriptions how it is done.
Could you please advice what approach to take, how to identify intersection of two or multiple curves and generate mesh junction?

Thank you

Similar to this

 

Find the point of intersection and construct a mesh that respects the lane widths using the corners that you get from calculating the intersection of the vectors along the edges of those lanes and stitch them together.
Alternatively find/write a method that just merges your already constructed plain meshes.
if you intend to make your roads more useful to scripting or customizable, that's alot more complicated.
You could have a look at https://github.com/MicroGSD/RoadArchitect that can probably give you some inspiration.

 

Hi Flavelius,

Thank you for the reply. Currently I am at very basic level. Can draw a line or curve with 2D mesh planes constructed along the path.

Having trouble to find an approach to find intersections of lines?

And I am not really sure I need to find an intersection of lines, maybe I have to find an intersection of meshes , using points coordinates with distance between them. If two points are close it means intersection is happening...

Really hard to find anything useful online

Just a wee test I did to explain what I am trying to achieve

Also planning to make general mesh class which I can use for roads and also for buildings and land. Not sure it will work though.

For land between roads, have you had a chance to find any good algorithm to generate a mesh from boundary points?

 

I'm not sure if finding intersections is actually a good approach. You're probably better off defining each part separately, roads, intersections, bridges etc.. and just find ways of connecting them correctly. But if there's a reason you want to do that anyway, maybe these will help:
https://github.com/Siccity/Geometry2D
https://github.com/DesignEngrLab/MIConvexHull
https://github.com/Geri-Borbas/Unity.Library.eppz.Geometry
https://github.com/mattatz/unity-triangulation2D

 

Thank you @Flavelius

 

Hi, would you like to elaborate a little bit more on this? I mean this part.
> construct a mesh that respects the lane widths using the corners that you get from calculating the intersection of the vectors along the edges of those lanes and stitch them together.

 

This touches a lot of topics, some with caveats that are quite complex. But basically, if you have a 'road', it's not just a line, it's more like two parallel 'edges' of that road that, when they intersect other edges (two roads joining) need to be merged with them. This involves calculating the point of intersection and tailoring your mesh generation algorithm to account for that. How that looks in detail will vary highly depending on everything involved. You could for example actually join them into a single mesh or, i think the linked asset does it, generate specific end-caps for each road and a separate joint-piece that conforms to those end-caps.