bbox.py

from .vec3 import Vec3


class BBox:
    """
    A bounding box class for 3D geometry.

    Stores center, dimensions, extents, vertices, and normals for a box.
    Provides methods to recalculate from center/dimensions or from extents.
    """

    def __init__(
        self,
        center: Vec3 = Vec3(),
        width: float = 2.0,
        height: float = 2.0,
        depth: float = 2.0,
    ) -> None:
        """
        Initialize a bounding box from center and dimensions.

        Args:
            center: Center of the bounding box (Vec3)
            width: Width of the box
            height: Height of the box
            depth: Depth of the box
        """
        self._center: Vec3 = center
        self._width: float = width
        self._height: float = height
        self._depth: float = depth
        self._min_x: float = 0.0
        self._max_x: float = 0.0
        self._min_y: float = 0.0
        self._max_y: float = 0.0
        self._min_z: float = 0.0
        self._max_z: float = 0.0
        self._verts: list[Vec3] = [Vec3() for _ in range(8)]
        self._normals: list[Vec3] = [Vec3() for _ in range(6)]
        self.recalculate_from_center_dims()

    @classmethod
    def from_extents(
        cls,
        min_x: float,
        max_x: float,
        min_y: float,
        max_y: float,
        min_z: float,
        max_z: float,
    ) -> "BBox":
        """
        Create a bounding box from min/max extents.

        Args:
            min_x, max_x, min_y, max_y, min_z, max_z: Box extents

        Returns:
            BBox: The constructed bounding box
        """
        bbox = cls()
        bbox.set_extents(min_x, max_x, min_y, max_y, min_z, max_z)
        return bbox

    @property
    def center(self) -> Vec3:
        """Get or set the center of the bounding box."""
        return self._center

    @center.setter
    def center(self, value: Vec3) -> None:
        self._center = value
        self.recalculate_from_center_dims()

    @property
    def width(self) -> float:
        """Get or set the width of the bounding box."""
        return self._width

    @width.setter
    def width(self, value: float) -> None:
        self._width = value
        self.recalculate_from_center_dims()

    @property
    def height(self) -> float:
        """Get or set the height of the bounding box."""
        return self._height

    @height.setter
    def height(self, value: float) -> None:
        self._height = value
        self.recalculate_from_center_dims()

    @property
    def depth(self) -> float:
        """Get or set the depth of the bounding box."""
        return self._depth

    @depth.setter
    def depth(self, value: float) -> None:
        self._depth = value
        self.recalculate_from_center_dims()

    @property
    def min_x(self) -> float:
        """Get the minimum x extent."""
        return self._min_x

    @property
    def max_x(self) -> float:
        """Get the maximum x extent."""
        return self._max_x

    @property
    def min_y(self) -> float:
        """Get the minimum y extent."""
        return self._min_y

    @property
    def max_y(self) -> float:
        """Get the maximum y extent."""
        return self._max_y

    @property
    def min_z(self) -> float:
        """Get the minimum z extent."""
        return self._min_z

    @property
    def max_z(self) -> float:
        """Get the maximum z extent."""
        return self._max_z

    def get_vertex_array(self) -> list[Vec3]:
        """
        Get the list of 8 vertices for the bounding box.

        Returns:
            list[Vec3]: The 8 vertices of the box.
        """
        return self._verts

    def get_normal_array(self) -> list[Vec3]:
        """
        Get the list of 6 normals for the bounding box faces.

        Returns:
            list[Vec3]: The 6 normals of the box.
        """
        return self._normals

    def set_extents(
        self,
        min_x: float,
        max_x: float,
        min_y: float,
        max_y: float,
        min_z: float,
        max_z: float,
    ) -> None:
        """
        Set the extents of the bounding box and recalculate center/dimensions.

        Args:
            min_x, max_x, min_y, max_y, min_z, max_z: Box extents
        """
        self._min_x = min_x
        self._max_x = max_x
        self._min_y = min_y
        self._max_y = max_y
        self._min_z = min_z
        self._max_z = max_z
        self.recalculate_from_extents()

    def recalculate_from_center_dims(self) -> None:
        """
        Recalculate extents and update vertices/normals from center and dimensions.
        """
        half_width = self._width / 2.0
        half_height = self._height / 2.0
        half_depth = self._depth / 2.0

        self._min_x = self._center.x - half_width
        self._max_x = self._center.x + half_width
        self._min_y = self._center.y - half_height
        self._max_y = self._center.y + half_height
        self._min_z = self._center.z - half_depth
        self._max_z = self._center.z + half_depth
        self._update_verts_and_normals()

    def recalculate_from_extents(self) -> None:
        """
        Recalculate center and dimensions from extents, then update vertices/normals.
        """
        self._width = self._max_x - self._min_x
        self._height = self._max_y - self._min_y
        self._depth = self._max_z - self._min_z
        self._center = Vec3(
            self._min_x + self._width / 2.0,
            self._min_y + self._height / 2.0,
            self._min_z + self._depth / 2.0,
        )
        self._update_verts_and_normals()

    def _update_verts_and_normals(self) -> None:
        """
        Update the 8 vertices and 6 normals of the bounding box based on current extents.
        """
        self._verts[0].set(self._min_x, self._max_y, self._min_z)
        self._verts[1].set(self._max_x, self._max_y, self._min_z)
        self._verts[2].set(self._max_x, self._max_y, self._max_z)
        self._verts[3].set(self._min_x, self._max_y, self._max_z)
        self._verts[4].set(self._min_x, self._min_y, self._min_z)
        self._verts[5].set(self._max_x, self._min_y, self._min_z)
        self._verts[6].set(self._max_x, self._min_y, self._max_z)
        self._verts[7].set(self._min_x, self._min_y, self._max_z)

        self._normals[0].set(0.0, 1.0, 0.0)
        self._normals[1].set(0.0, -1.0, 0.0)
        self._normals[2].set(1.0, 0.0, 0.0)
        self._normals[3].set(-1.0, 0.0, 0.0)
        self._normals[4].set(0.0, 0.0, 1.0)
        self._normals[5].set(0.0, 0.0, -1.0)