u/DrSnorkel

The terrain itself is generated with Godot's FastNoiseLite during load time.

For the unit ground 'collision' I created a job that uses bilinear interpolations of the surrounding heights to adjust the unit position.

For the terrain destruction, the vertex positions get updated on the CPU via a job. The difficult part was updating the mesh. I did multiple attempts to get this working fast enough.

The first attempt was creating a new mesh each time, but this was slow (14ms) and allocated both native and managed memory each time.

Second attempt was using RenderServer.mesh_surface_update_vertex_region but I couldn't figure out how to send the vertex normals with RenderServer.mesh_surface_update_attribute_region. I gave up on this.

Third attempt I created a 32bit floating point ImageTexture and set the data with the float[] of the terrain heights.

In the vertex shader I read the height and adjust the vertex position. Then vertex shader calculates the vertex normal using neighbouring height texture samples. This works great! Whole terrain updates in 0.6 ms. (Bonus: the height texture can be used for all kinds of effects later)

I've also added blob shadows to all the units so they are easier to see.

In this test 10000 units move towards the mouse position with a poor attempt at avoidance.

All unit data is stored in multiple arrays e.g: position[10000], velocity[10000], etc

Each 'job' is split evenly over multiple thread, including the main thread. The main thread helps and then waits until the other threads are complete.

At the end a buffer of transforms is constructed in a 'job' and then on the mainthread it is copied to a MultiMesh.

The explosion forces are also checked using threading. Each click position is added to a list, then each thread check for a bunch of units for each click position and applies it to its unit.

(The movement code assume to floor is a plane, there is no physics or nodes used for the units. All interaction with Godot happens on the main thread.)

Might turn this into a tower defence.