caps, visual mode

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Seth Trowbridge 2026-02-28 07:10:34 -05:00
parent ed5457ecc2
commit 101e8bc86b

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@ -2,147 +2,185 @@
Armature Mesher - Blender Addon
Converts a selected armature into an envelope-style mesh using each bone's
head/tail radius values (exactly like Envelope display mode).
Supports:
- Object mode rest pose (arm.bones)
- Pose mode current pose (obj.pose.bones)
- Edit mode current edit-bone positions
Geometry:
- UV-sphere at head and tail (head_radius / tail_radius)
- Capped frustum cylinder connecting the two spheres
"""
import bpy
import bmesh
import math
from mathutils import Vector, Matrix, Quaternion
from mathutils import Vector, Matrix
# ---------------------------------------------------------------------------
# Geometry helpers
# ---------------------------------------------------------------------------
def make_sphere_bmesh(bm, center: Vector, radius: float, segments: int = 12) -> list:
"""Add a UV-sphere to an existing BMesh, return the new verts."""
verts = []
rings = segments // 2
for ring in range(rings + 1):
phi = math.pi * ring / rings # 0 … π
for seg in range(segments):
theta = 2 * math.pi * seg / segments
x = radius * math.sin(phi) * math.cos(theta)
y = radius * math.sin(phi) * math.sin(theta)
z = radius * math.cos(phi)
verts.append(bm.verts.new(center + Vector((x, y, z))))
def _rotation_matrix_to_axis(target_axis: Vector) -> Matrix:
"""Return a 4x4 rotation matrix that rotates Z → target_axis."""
ax = target_axis.normalized()
z = Vector((0.0, 0.0, 1.0))
cross = z.cross(ax)
if cross.length < 1e-6:
if ax.z > 0:
return Matrix.Identity(4)
else:
return Matrix.Rotation(math.pi, 4, 'X')
angle = math.acos(max(-1.0, min(1.0, z.dot(ax))))
return Matrix.Rotation(angle, 4, cross.normalized())
# Connect rings
for ring in range(rings):
for seg in range(segments):
nxt = (seg + 1) % segments
v0 = verts[ring * segments + seg]
v1 = verts[ring * segments + nxt]
v2 = verts[(ring + 1) * segments + nxt]
v3 = verts[(ring + 1) * segments + seg]
def add_sphere(bm: bmesh.types.BMesh, center: Vector, radius: float, segments: int):
"""Add a closed UV-sphere to bm."""
rings = max(segments // 2, 2)
verts = []
for r in range(rings + 1):
phi = math.pi * r / rings
sin_phi = math.sin(phi)
cos_phi = math.cos(phi)
for s in range(segments):
theta = 2.0 * math.pi * s / segments
v = bm.verts.new(center + Vector((
radius * sin_phi * math.cos(theta),
radius * sin_phi * math.sin(theta),
radius * cos_phi,
)))
verts.append(v)
for r in range(rings):
for s in range(segments):
s_next = (s + 1) % segments
v0 = verts[r * segments + s]
v1 = verts[r * segments + s_next]
v2 = verts[(r + 1) * segments + s_next]
v3 = verts[(r + 1) * segments + s]
try:
bm.faces.new((v0, v1, v2, v3))
except ValueError:
pass
return verts
# ---------------------------------------------------------------------------
# Core build function
# ---------------------------------------------------------------------------
SEGMENTS = 16 # quality — increase for smoother result
def build_envelope_mesh(armature_obj: bpy.types.Object) -> bpy.types.Object:
arm = armature_obj.data
world_mat = armature_obj.matrix_world
bm = bmesh.new()
for bone in arm.bones:
# Bone head/tail in armature local space
head_local = bone.head_local # Vector
tail_local = bone.tail_local
# Convert to world space
head_w = world_mat @ head_local
tail_w = world_mat @ tail_local
head_r = bone.head_radius
tail_r = bone.tail_radius
# Clamp radii to something visible
head_r = max(head_r, 0.001)
tail_r = max(tail_r, 0.001)
# Head sphere
make_sphere_bmesh(bm, head_w, head_r, SEGMENTS)
# Tail sphere
make_sphere_bmesh(bm, tail_w, tail_r, SEGMENTS)
# Connecting frustum
axis = tail_w - head_w
def add_capped_frustum(bm: bmesh.types.BMesh,
head_center: Vector, head_radius: float,
tail_center: Vector, tail_radius: float,
segments: int):
"""
Add a capped tapered cylinder between two sphere centers.
Rings are placed at the sphere equators (offset = radius along axis)
so they sit flush with the sphere surfaces.
Each open end is closed with a triangle fan cap.
"""
axis = tail_center - head_center
length = axis.length
if length < 1e-6:
continue
return
ax = axis.normalized()
rot = _rotation_matrix_to_axis(ax)
def ring_offset(sphere_r, ring_r):
rr = min(ring_r, sphere_r)
return math.sqrt(max(sphere_r ** 2 - rr ** 2, 0.0))
# Place rings at the sphere equators along the bone axis
head_ring_center = head_center + ax * head_radius
tail_ring_center = tail_center - ax * tail_radius
head_off = ring_offset(head_r, head_r)
tail_off = ring_offset(tail_r, tail_r)
ring_head_pt = head_w + ax * head_off
ring_tail_pt = tail_w - ax * tail_off
# Only draw frustum if ring planes don't overlap
if (ring_tail_pt - ring_head_pt).dot(ax) < 1e-6:
continue
# Build local rotation matrix aligning Z to bone axis
z = Vector((0, 0, 1))
cross = z.cross(ax)
if cross.length < 1e-6:
rot = Matrix.Identity(4) if ax.z > 0 else Matrix.Rotation(math.pi, 4, 'X')
else:
angle = math.acos(max(-1.0, min(1.0, z.dot(ax))))
rot = Matrix.Rotation(angle, 4, cross.normalized())
# Skip if rings would overlap (bone too short relative to radii)
if (tail_ring_center - head_ring_center).dot(ax) < 1e-6:
return
# Build the two rings
head_ring = []
tail_ring = []
for i in range(SEGMENTS):
theta = 2 * math.pi * i / SEGMENTS
lv = Vector((math.cos(theta), math.sin(theta), 0.0))
rv = rot @ lv
head_ring.append(bm.verts.new(ring_head_pt + rv * head_r))
tail_ring.append(bm.verts.new(ring_tail_pt + rv * tail_r))
for i in range(segments):
theta = 2.0 * math.pi * i / segments
local = Vector((math.cos(theta), math.sin(theta), 0.0))
# rot is 4x4; multiply then drop w component
offset = (rot @ local.to_4d()).to_3d()
head_ring.append(bm.verts.new(head_ring_center + offset * head_radius))
tail_ring.append(bm.verts.new(tail_ring_center + offset * tail_radius))
for i in range(SEGMENTS):
nxt = (i + 1) % SEGMENTS
# Side quads
for i in range(segments):
nxt = (i + 1) % segments
try:
bm.faces.new((head_ring[i], head_ring[nxt],
tail_ring[nxt], tail_ring[i]))
except ValueError:
pass
# Merge overlapping verts (where spheres from adjacent bones touch)
bmesh.ops.remove_doubles(bm, verts=bm.verts, dist=0.0001)
# Head cap — fan, winding faces inward (away from tail)
head_cap_v = bm.verts.new(head_ring_center)
for i in range(segments):
nxt = (i + 1) % segments
try:
bm.faces.new((head_cap_v, head_ring[nxt], head_ring[i]))
except ValueError:
pass
# Create mesh data-block
mesh = bpy.data.meshes.new(armature_obj.name + "_envelope_mesh")
bm.to_mesh(mesh)
bm.free()
# Tail cap — fan, winding faces outward (away from head)
tail_cap_v = bm.verts.new(tail_ring_center)
for i in range(segments):
nxt = (i + 1) % segments
try:
bm.faces.new((tail_cap_v, tail_ring[i], tail_ring[nxt]))
except ValueError:
pass
mesh.update()
# Create object
obj = bpy.data.objects.new(armature_obj.name + "_envelope", mesh)
bpy.context.collection.objects.link(obj)
# ---------------------------------------------------------------------------
# Bone data collection — mode-aware
# ---------------------------------------------------------------------------
return obj
def collect_bone_data(arm_obj) -> list:
"""
Returns a list of dicts with world-space head/tail and radii.
Reads from the appropriate source based on the armature's current mode:
OBJECT arm.bones (rest pose)
POSE obj.pose.bones (current posed positions)
EDIT arm.edit_bones (what you see in edit mode)
"""
mode = arm_obj.mode
world_mat = arm_obj.matrix_world
result = []
if mode == 'POSE':
for pb in arm_obj.pose.bones:
b = pb.bone # underlying data bone for radii
result.append({
'head': world_mat @ pb.head,
'tail': world_mat @ pb.tail,
'head_r': max(b.head_radius, 0.001),
'tail_r': max(b.tail_radius, 0.001),
})
elif mode == 'EDIT':
# edit_bones is accessible while in edit mode
for eb in arm_obj.data.edit_bones:
result.append({
'head': world_mat @ eb.head,
'tail': world_mat @ eb.tail,
'head_r': max(eb.head_radius, 0.001),
'tail_r': max(eb.tail_radius, 0.001),
})
else: # OBJECT / everything else → rest pose
for bone in arm_obj.data.bones:
result.append({
'head': world_mat @ bone.head_local,
'tail': world_mat @ bone.tail_local,
'head_r': max(bone.head_radius, 0.001),
'tail_r': max(bone.tail_radius, 0.001),
})
return result
# ---------------------------------------------------------------------------
@ -153,17 +191,15 @@ class ARMATURE_OT_build_envelope_mesh(bpy.types.Operator):
bl_idname = "armature.build_envelope_mesh"
bl_label = "Build Envelope Mesh"
bl_description = (
"Convert the selected armature into a mesh that mirrors its "
"Envelope display (spheres at joints, tapered cylinders along bones)"
"Convert the selected armature into an envelope-style mesh. "
"Object mode = rest pose | Pose mode = current pose | Edit mode = edit bones."
)
bl_options = {'REGISTER', 'UNDO'}
segments: bpy.props.IntProperty(
name="Segments",
description="Cylinder / sphere resolution",
default=16,
min=4,
max=64,
description="Sphere / cylinder resolution",
default=16, min=4, max=64,
)
@classmethod
@ -172,23 +208,59 @@ class ARMATURE_OT_build_envelope_mesh(bpy.types.Operator):
return obj is not None and obj.type == 'ARMATURE'
def execute(self, context):
global SEGMENTS
SEGMENTS = self.segments
arm_obj = context.active_object
original_mode = arm_obj.mode
# Ensure we have edit-mode bone data (rest-pose local coords)
if arm_obj.mode != 'OBJECT':
# Snapshot bone data NOW, while we're still in the original mode.
# This is especially important for EDIT mode where edit_bones are live.
bones_data = collect_bone_data(arm_obj)
# Must be in OBJECT mode to create and link new mesh objects.
if original_mode != 'OBJECT':
bpy.ops.object.mode_set(mode='OBJECT')
result_obj = build_envelope_mesh(arm_obj)
# Build the BMesh
bm = bmesh.new()
segs = self.segments
for bd in bones_data:
add_sphere(bm, bd['head'], bd['head_r'], segs)
add_sphere(bm, bd['tail'], bd['tail_r'], segs)
add_capped_frustum(bm,
bd['head'], bd['head_r'],
bd['tail'], bd['tail_r'],
segs)
# Merge verts from shared joints (parent/child bone connections)
bmesh.ops.remove_doubles(bm, verts=bm.verts, dist=0.0001)
mesh = bpy.data.meshes.new(arm_obj.name + "_envelope_mesh")
bm.to_mesh(mesh)
bm.free()
mesh.update()
result_obj = bpy.data.objects.new(arm_obj.name + "_envelope", mesh)
context.collection.objects.link(result_obj)
# Re-enter edit mode on the armature if that's where we came from,
# then make the new mesh the active/selected object.
if original_mode == 'EDIT':
arm_obj.select_set(True)
context.view_layer.objects.active = arm_obj
bpy.ops.object.mode_set(mode='EDIT')
arm_obj.select_set(False)
# Select the new mesh
bpy.ops.object.select_all(action='DESELECT')
result_obj.select_set(True)
context.view_layer.objects.active = result_obj
self.report({'INFO'}, f"Created: {result_obj.name}")
source_label = {
'OBJECT': "rest pose",
'POSE': "current pose",
'EDIT': "edit-bone layout",
}.get(original_mode, original_mode)
self.report({'INFO'}, f"Created '{result_obj.name}' from {source_label}.")
return {'FINISHED'}
@ -205,12 +277,19 @@ class VIEW3D_PT_armature_mesher(bpy.types.Panel):
@classmethod
def poll(cls, context):
return (context.active_object is not None and
context.active_object.type == 'ARMATURE')
obj = context.active_object
return obj is not None and obj.type == 'ARMATURE'
def draw(self, context):
layout = self.layout
layout.label(text="Selected: " + context.active_object.name)
obj = context.active_object
mode_labels = {
'OBJECT': "Object → rest pose",
'POSE': "Pose → current pose",
'EDIT': "Edit → edit bones",
}
layout.label(text=obj.name)
layout.label(text=mode_labels.get(obj.mode, obj.mode), icon='INFO')
layout.separator()
op = layout.operator(
ARMATURE_OT_build_envelope_mesh.bl_idname,
@ -229,16 +308,13 @@ classes = (
VIEW3D_PT_armature_mesher,
)
def register():
for cls in classes:
bpy.utils.register_class(cls)
def unregister():
for cls in reversed(classes):
bpy.utils.unregister_class(cls)
if __name__ == "__main__":
register()