Alternate mesh quad diagonals for symmetrical grid

[Radivarig]

Description

Alternating diagonals would allow symmetrical deformations and reduce the zigzag triangle spikes.

@tool
extends MeshInstance3D

@export_group("Click to generate")
@export var generate: bool:
    set(value):
        if value:
            _generate_grid()

@export var size = Vector2i(10, 10)

func _ready():
    _generate_grid()

func _generate_grid():
    if mesh:
        mesh = null

    var immediate_mesh = ImmediateMesh.new()
    immediate_mesh.surface_begin(Mesh.PRIMITIVE_TRIANGLES)

    for x in range(size.x):
        for y in range(size.y):
            var top_left = Vector3(x, 0, y + 1)
            var top_right = Vector3(x + 1, 0, y + 1)
            var bottom_left = Vector3(x, 0, y)
            var bottom_right = Vector3(x + 1, 0, y)

            if (x + y) % 2 == 0:
                immediate_mesh.surface_add_vertex(bottom_left)
                immediate_mesh.surface_add_vertex(top_right)
                immediate_mesh.surface_add_vertex(top_left)
                
                immediate_mesh.surface_add_vertex(bottom_left)
                immediate_mesh.surface_add_vertex(bottom_right)
                immediate_mesh.surface_add_vertex(top_right)
            else:
                immediate_mesh.surface_add_vertex(bottom_left)
                immediate_mesh.surface_add_vertex(bottom_right)
                immediate_mesh.surface_add_vertex(top_left)
                
                immediate_mesh.surface_add_vertex(top_left)
                immediate_mesh.surface_add_vertex(bottom_right)
                immediate_mesh.surface_add_vertex(top_right)

    immediate_mesh.surface_end()
    mesh = immediate_mesh

[TokisanGames]

Collision works using a HeightMapShape. The mesh is perfectly aligned with the collision shape. Your suggestion, as is, will make the collision shape and mesh be out of alignment pretty much everywhere between vertices except on flat areas. We would have to generate our own collision shape. If we did it would be after #278.

Also I intend to experiment with triangle strips and a meshless terrain. I don't believe that pattern can be made with them.

Another solution might be #228 tessellation and/or non-uniform lods. Though I do see Witcher3 uses a symmetric grid.

[Radivarig]

Custom collisions sound great especially with a radius where chunks would spawn.

Another example is WoW terrain using the symmetric grid.