export_skydome_geometry.py

"""
This script generates the skydome geometry data as stored in
iron/Sources/iron/data/ConstData.hx.

USAGE:
    On MacOS/Linux:
        Open Blender from the terminal to see the console output.
    On Windows:
        Open the Blender console via "Window > Toggle System Console".

    Select the skydome object in object mode and run this script. Note
    that the script flips the normals in the output. The original mesh
    is not modified.

    After running the script, open the console. If the script ran
    successfully, the generated vertex data was printed to the console,
    ready to copy to ConstData.hx.
"""
import bmesh
import bpy


def list_representation(lst) -> str:
    """List to string without spaces."""
    return f"[{','.join(str(i) for i in lst)}]"


def run():
    obj = bpy.context.object

    if obj is None:
        print("No object selected, aborting!")
        return

    if obj.type != "MESH":
        print(f"Selected object '{obj.name}' is not a mesh, aborting!")
        return

    bm = bmesh.new()
    bm.from_mesh(obj.data)
    bmesh.ops.triangulate(bm, faces=bm.faces[:], quad_method="FIXED")

    indices = []
    positions = []
    normals = []

    # Fill index buffer
    for face in bm.faces:
        # Turn the normals inside for correct winding order of indices
        face.normal_flip()

        for vert in face.verts:
            indices.append(vert.index)

    # Vertex buffer data
    for vert in bm.verts:
        positions.extend(vert.co)
        # Blender world normals have mirrored coords compared to spheres
        nor = vert.normal
        nor.negate()
        normals.extend(nor)

    pos_rounded = [round(elem, 5) for elem in positions]
    nor_rounded = [round(elem, 5) for elem in normals]

    bm.free()

    print("\n====================")
    print(f"Calculated mesh data for object '{obj.name}':")
    print(f"Indices: {list_representation(indices)}")
    print("")
    print(f"Positions: {list_representation(pos_rounded)}")
    print("")
    print(f"Normals: {list_representation(nor_rounded)}")


if __name__ == "__main__":
    run()