PlaneMeshBuilder: Different amounts of subdivisions in X and Z directions

[ulmer-a]

What problem does this solve or what need does it fill?

I have a use case where I need a plane mesh that has different amounts of subdivisions in the x and z directions, respectively. When I use PlaneMeshBuilderto build the mesh, I only have the option to do this:

Plane3d::default()
    .mesh()
    .size(100, 100)
    .subdivisions(5), // can only do this where i would like to do `.subdivisions_xz(5, 10)`

What solution would you like?

This could be trivially implemented by just changing this

pub struct PlaneMeshBuilder {
    pub plane: Plane3d,
    pub subdivisions: u32,
}

impl MeshBuilder for PlaneMeshBuilder {
    fn build(&self) -> Mesh {
        let z_vertex_count = self.subdivisions + 2;
        let x_vertex_count = self.subdivisions + 2;
        let num_vertices = (z_vertex_count * x_vertex_count) as usize;
        // ...

into this:

pub struct PlaneMeshBuilder {
    pub plane: Plane3d,
    pub subdivisions_x: u32,
    pub subdivisions_z: u32,
}

impl MeshBuilder for PlaneMeshBuilder {
    fn build(&self) -> Mesh {
        let z_vertex_count = self.subdivisions_z + 2;
        let x_vertex_count = self.subdivisions_x + 2;
        let num_vertices = (z_vertex_count * x_vertex_count) as usize;
        // ...

and of course adding the corresponding builder methods etc. Also, the current API would not change!

Additional context

The issue where subdivisions were introduced: #13258. Someone mentioned that subdivisions should be part of Meshable trait. Is this relevant?

I would be happy to implement this if you guys approve this.