simvx.core.surface_tool

Procedural geometry construction tool and convenience mesh generators.

SurfaceTool provides a vertex-by-vertex mesh building API inspired by Godot’s SurfaceTool. ImmediateGeometry3D rebuilds its mesh every frame from a user callback, suitable for debug visualisations, trails, and dynamic geometry.

Usage::

from simvx.core import SurfaceTool, PrimitiveType

st = SurfaceTool()
st.begin(PrimitiveType.TRIANGLES)
st.set_normal((0, 1, 0))
st.set_uv((0, 0))
st.add_vertex((0, 0, 0))
st.set_uv((1, 0))
st.add_vertex((1, 0, 0))
st.set_uv((0.5, 1))
st.add_vertex((0.5, 1, 0))
mesh = st.commit()

Module Contents

Classes

PrimitiveType	Primitive topology for SurfaceTool.
SurfaceTool	Vertex-by-vertex mesh construction tool.
ImmediateGeometry3D	A 3D node whose mesh is rebuilt every frame via a callback.

Functions

create_box	Create a box mesh centred at the origin.
create_sphere	Create a UV sphere mesh centred at the origin.
create_cylinder	Create a cylinder mesh along the Y axis, centred at the origin.
create_plane	Create a flat plane on the XZ plane, centred at the origin.
create_capsule	Create a capsule mesh (cylinder with hemispherical caps) along the Y axis.

Data

log
__all__

API

simvx.core.surface_tool.log

‘getLogger(…)’

simvx.core.surface_tool.__all__

[‘SurfaceTool’, ‘PrimitiveType’, ‘ImmediateGeometry3D’, ‘create_box’, ‘create_sphere’, ‘create_cylin…

class simvx.core.surface_tool.PrimitiveType

Bases: enum.IntEnum

Primitive topology for SurfaceTool.

Initialization

Initialize self. See help(type(self)) for accurate signature.

TRIANGLES

0

LINES

1

POINTS

2

TRIANGLE_STRIP

3

__abs__()

__add__()

__and__()

__bool__()

__ceil__()

__delattr__()

__dir__()

__divmod__()

__eq__()

__float__()

__floor__()

__floordiv__()

__format__()

__ge__()

__getattribute__()

__getnewargs__()

__getstate__()

__gt__()

__hash__()

__index__()

__int__()

__invert__()

__le__()

__lshift__()

__lt__()

__mod__()

__mul__()

__ne__()

__neg__()

__new__()

__or__()

__pos__()

__pow__()

__radd__()

__rand__()

__rdivmod__()

__reduce__()

__reduce_ex__()

__repr__()

__rfloordiv__()

__rlshift__()

__rmod__()

__rmul__()

__ror__()

__round__()

__rpow__()

__rrshift__()

__rshift__()

__rsub__()

__rtruediv__()

__rxor__()

__setattr__()

__sizeof__()

__str__()

__sub__()

__subclasshook__()

__truediv__()

__trunc__()

__xor__()

as_integer_ratio()

bit_count()

bit_length()

conjugate()

class denominator

class imag

is_integer()

class numerator

class real

to_bytes()

__deepcopy__(memo)

__copy__()

name()

value()

class simvx.core.surface_tool.SurfaceTool

Vertex-by-vertex mesh construction tool.

Accumulates vertex attributes then emits a Mesh on commit(). Set per-vertex attributes (normal, uv, colour) before calling add_vertex() – the current values are latched when the vertex is added.

Initialization

__slots__

(‘_primitive’, ‘_positions’, ‘_normals’, ‘_uvs’, ‘_colours’, ‘_indices’, ‘_cur_normal’, ‘_cur_uv’, ‘…

begin(primitive: simvx.core.surface_tool.PrimitiveType = PrimitiveType.TRIANGLES) → None

Start a new surface. Clears any previously accumulated data.

set_normal(normal: collections.abc.Sequence[float] | simvx.core.math.types.Vec3) → None

Set the normal for subsequent vertices.

set_uv(uv: collections.abc.Sequence[float] | simvx.core.math.types.Vec2) → None

Set the UV coordinate for subsequent vertices.

set_colour(colour: collections.abc.Sequence[float]) → None

Set the vertex colour (RGBA) for subsequent vertices.

add_vertex(position: collections.abc.Sequence[float] | simvx.core.math.types.Vec3) → None

Add a vertex with the currently set attributes.

add_index(index: int) → None

Add an index referencing a previously added vertex.

add_triangle_fan(vertices: collections.abc.Sequence[collections.abc.Sequence[float]], uvs: collections.abc.Sequence[collections.abc.Sequence[float]] | None = None, normals: collections.abc.Sequence[collections.abc.Sequence[float]] | None = None) → None

Add a triangle fan as indexed triangles.

The first vertex is the hub; triangles are formed with consecutive pairs of the remaining vertices.

generate_normals() → None

Auto-compute smooth normals from triangle geometry.

Only works when primitive type is TRIANGLES. Uses the index list if present, otherwise assumes every three consecutive vertices form a triangle.

generate_tangents() → None

Auto-compute tangents using Lengyel’s method (MikkTSpace-lite).

Stores tangent data on the resulting mesh as a tangents attribute (Nx4 float32 array with w = handedness). This is a best-effort implementation suitable for normal mapping.

commit() → simvx.core.graphics.mesh.Mesh

Build and return a Mesh from the accumulated vertex data.

clear() → None

Reset the tool for reuse (same as constructing a new instance).

property vertex_count: int

Number of vertices accumulated so far.

property index_count: int

Number of indices accumulated so far.

class simvx.core.surface_tool.ImmediateGeometry3D(**kwargs)

Bases: simvx.core.nodes_3d.node3d.Node3D

A 3D node whose mesh is rebuilt every frame via a callback.

Override _draw_geometry or connect to the draw signal to provide geometry each frame. The node creates a fresh SurfaceTool, passes it to your callback, and commits the result as the renderable mesh.

Usage::

class MyTrail(ImmediateGeometry3D):
    def _draw_geometry(self, st: SurfaceTool) -> None:
        st.begin(PrimitiveType.TRIANGLES)
        # ... add vertices ...

Or with signals::

def draw_fn(st: SurfaceTool) -> None:
    st.begin(PrimitiveType.TRIANGLES)
    # ...

ig = ImmediateGeometry3D()
ig.draw.connect(draw_fn)

Initialization

process(dt: float) → None

render_layer

‘Property(…)’

property position

property rotation: simvx.core.math.types.Quat

property scale

property rotation_degrees: simvx.core.math.types.Vec3

property world_position: simvx.core.math.types.Vec3

property world_rotation: simvx.core.math.types.Quat

property world_scale: simvx.core.math.types.Vec3

property forward: simvx.core.math.types.Vec3

property right: simvx.core.math.types.Vec3

property up: simvx.core.math.types.Vec3

translate(offset: tuple[float, float, float] | numpy.ndarray)

translate_global(offset: tuple[float, float, float] | numpy.ndarray)

rotate(axis: tuple[float, float, float] | numpy.ndarray, angle: float)

rotate_x(angle: float)

rotate_y(angle: float)

rotate_z(angle: float)

look_at(target: tuple[float, float, float] | numpy.ndarray, up=None)

set_render_layer(index: int, enabled: bool = True) → None

is_on_render_layer(index: int) → bool

wrap_bounds(bounds: tuple[float, float, float] | numpy.ndarray, margin: float = 1.0)

strict_errors: ClassVar[bool]

True

script_error_raised

‘Signal(…)’

classmethod __init_subclass__(**kwargs)

property name: str

property process_mode: simvx.core.descriptors.ProcessMode

reset_error() → None

add_child(node: simvx.core.node.Node) → simvx.core.node.Node

remove_child(node: simvx.core.node.Node)

reparent(new_parent: simvx.core.node.Node)

get_node(path: str) → simvx.core.node.Node

find_child(name: str, recursive: bool = False) → simvx.core.node.Node | None

find(node_type: type, recursive: bool = True) → simvx.core.node.Node | None

find_all(node_type: type, recursive: bool = True) → list

property path: str

add_to_group(group: str)

remove_from_group(group: str)

is_in_group(group: str) → bool

ready() → None

enter_tree() → None

exit_tree() → None

physics_process(dt: float) → None

draw(renderer) → None

input_event(event: simvx.core.events.InputEvent) → None

input(event: simvx.core.events.TreeInputEvent) → None

unhandled_input(event: simvx.core.events.TreeInputEvent) → None

start_coroutine(gen: simvx.core.descriptors.Coroutine) → simvx.core.descriptors.CoroutineHandle

stop_coroutine(gen_or_handle)

clear_children()

destroy()

property app

property tree: simvx.core.scene_tree.SceneTree

get_tree() → simvx.core.scene_tree.SceneTree

__getitem__(key: str)

classmethod get_properties() → dict[str, simvx.core.descriptors.Property]

__repr__()

simvx.core.surface_tool.create_box(size: float | collections.abc.Sequence[float] = 1.0) → simvx.core.graphics.mesh.Mesh

Create a box mesh centred at the origin.

Args: size: Uniform size (float) or per-axis extents (x, y, z).

Returns: A Mesh with 24 vertices and 36 indices.

simvx.core.surface_tool.create_sphere(radius: float = 1.0, rings: int = 16, sectors: int = 16) → simvx.core.graphics.mesh.Mesh

Create a UV sphere mesh centred at the origin.

Args: radius: Sphere radius. rings: Number of horizontal rings (latitude divisions). sectors: Number of vertical sectors (longitude divisions).

Returns: A Mesh with smooth normals and UVs.

simvx.core.surface_tool.create_cylinder(radius: float = 0.5, height: float = 1.0, segments: int = 16) → simvx.core.graphics.mesh.Mesh

Create a cylinder mesh along the Y axis, centred at the origin.

Args: radius: Cylinder radius. height: Total height. segments: Number of radial segments.

Returns: A Mesh with side, top cap, and bottom cap geometry.

simvx.core.surface_tool.create_plane(size: float | collections.abc.Sequence[float] = 1.0, subdivisions: int = 1) → simvx.core.graphics.mesh.Mesh

Create a flat plane on the XZ plane, centred at the origin.

Args: size: Uniform size (float) or (width, depth) tuple. subdivisions: Number of subdivisions per axis (1 = single quad).

Returns: A Mesh with upward-facing normals.

simvx.core.surface_tool.create_capsule(radius: float = 0.5, height: float = 1.0, rings: int = 8, sectors: int = 16) → simvx.core.graphics.mesh.Mesh

Create a capsule mesh (cylinder with hemispherical caps) along the Y axis.

Args: radius: Capsule radius. height: Total height including the hemispherical caps. rings: Number of rings per hemisphere. sectors: Number of radial sectors.

Returns: A Mesh with smooth normals.