Testacode LLM Toolkit Blender Architect

Blender Architect

Professional architectural modeling workflow for Blender via MCP.

Prerequisites

• Blender with MCP addon connected
• Verify connection: mcp__blender__get_scene_info

Core Workflow

Phase 1: Scene Setup

import bpy

# Clear scene
bpy.ops.object.select_all(action='SELECT')
bpy.ops.object.delete()

# Create ground at Z=0
bpy.ops.mesh.primitive_plane_add(size=1, location=(width/2, length/2, 0))
ground = bpy.context.active_object
ground.name = "Ground"
ground.scale = (width, length, 1)
bpy.ops.object.transform_apply(scale=True)

Phase 2: Wall Creation (Solidify Method)

Key technique: Create 2D outline → Solidify for thickness → Extrude for height.

import bmesh

def create_walls_from_outline(vertices, thickness=0.20, height=2.95, name="Walls"):
    """
    vertices: list of (x, y) tuples defining wall outline
    thickness: wall thickness in meters
    height: wall height in meters
    """
    # Create mesh from vertices
    mesh = bpy.data.meshes.new(f"{name}_mesh")
    obj = bpy.data.objects.new(name, mesh)
    bpy.context.collection.objects.link(obj)

    bm = bmesh.new()
    verts = [bm.verts.new((v[0], v[1], 0)) for v in vertices]

    # Create edges (closed loop)
    for i in range(len(verts)):
        bm.edges.new((verts[i], verts[(i+1) % len(verts)]))

    # Create face from edges
    bm.faces.new(verts)
    bm.to_mesh(mesh)
    bm.free()

    # Solidify for wall thickness
    solidify = obj.modifiers.new("Solidify", 'SOLIDIFY')
    solidify.thickness = thickness
    solidify.offset = -1
    solidify.use_even_offset = True

    bpy.context.view_layer.objects.active = obj
    bpy.ops.object.modifier_apply(modifier="Solidify")

    # Extrude for height
    bpy.ops.object.mode_set(mode='EDIT')
    bpy.ops.mesh.select_all(action='SELECT')
    bpy.ops.mesh.extrude_region_move(
        TRANSFORM_OT_translate={"value": (0, 0, height)}
    )
    bpy.ops.object.mode_set(mode='OBJECT')

    return obj

Phase 3: Openings (Boolean Method)

def create_opening(wall_obj, location, size, name="Opening"):
    """
    Cut door/window opening using boolean difference.
    location: (x, y, z) center of opening
    size: (width, depth, height) of opening
    """
    # Create cutter
    bpy.ops.mesh.primitive_cube_add(size=1, location=location)
    cutter = bpy.context.active_object
    cutter.name = f"Cutter_{name}"
    cutter.scale = (size[0]/2, size[1]/2, size[2]/2)
    bpy.ops.object.transform_apply(scale=True)

    # Boolean difference
    bool_mod = wall_obj.modifiers.new(f"Bool_{name}", 'BOOLEAN')
    bool_mod.operation = 'DIFFERENCE'
    bool_mod.object = cutter

    bpy.context.view_layer.objects.active = wall_obj
    bpy.ops.object.modifier_apply(modifier=f"Bool_{name}")

    # Remove cutter
    bpy.data.objects.remove(cutter)

Phase 4: Roof

def create_sloped_roof(vertices, base_height, slope_percent=10, overhang=0.3):
    """
    Create inclined roof slab.
    slope_percent: 5-15% typical for residential
    """
    import math

    bpy.ops.mesh.primitive_plane_add(size=1)
    roof = bpy.context.active_object
    roof.name = "Roof"

    # Position and scale
    min_x = min(v[0] for v in vertices) - overhang
    max_x = max(v[0] for v in vertices) + overhang
    min_y = min(v[1] for v in vertices) - overhang
    max_y = max(v[1] for v in vertices) + overhang

    width = max_x - min_x
    length = max_y - min_y

    roof.location = ((min_x + max_x)/2, (min_y + max_y)/2, base_height)
    roof.scale = (width, length, 1)
    bpy.ops.object.transform_apply(scale=True)

    # Apply slope
    slope_rad = math.atan(slope_percent / 100)
    roof.rotation_euler = (slope_rad, 0, 0)

    # Add thickness
    solidify = roof.modifiers.new("Thickness", 'SOLIDIFY')
    solidify.thickness = 0.15
    bpy.ops.object.modifier_apply(modifier="Thickness")

    return roof

Phase 5: Materials

def create_arch_material(name, color, roughness=0.8, metallic=0.0):
    mat = bpy.data.materials.new(name=name)
    mat.use_nodes = True
    bsdf = mat.node_tree.nodes["Principled BSDF"]
    bsdf.inputs["Base Color"].default_value = (*color, 1)
    bsdf.inputs["Roughness"].default_value = roughness
    bsdf.inputs["Metallic"].default_value = metallic
    return mat

# Standard materials
MATERIALS = {
    "wall_exterior": ((0.75, 0.75, 0.73), 0.9, 0.0),
    "wall_interior": ((0.95, 0.95, 0.93), 0.95, 0.0),
    "concrete": ((0.5, 0.5, 0.5), 0.8, 0.0),
    "metal_black": ((0.05, 0.05, 0.05), 0.2, 0.9),
    "roof_metal": ((0.35, 0.35, 0.38), 0.4, 0.7),
    "glass": ((0.8, 0.85, 0.9), 0.0, 0.0),
}

Complete House Example

See references/house_example.md for full implementation.

Standard Dimensions

Common Mistakes to Avoid

1. Floating objects - Always start from Z=0
2. Separate cubes for walls - Use Solidify on outline instead
3. Overlapping windows - Use Boolean to cut, don't place on top
4. Missing scale apply - Always bpy.ops.object.transform_apply(scale=True)
5. Wrong normals - Recalculate after boolean operations

Troubleshooting

• Boolean fails: Check mesh is manifold, no self-intersections
• Solidify uneven: Enable "Even Thickness" option
• Objects not visible: Check collection visibility and Z position
• MCP unavailable: Ensure Blender MCP addon is running and reconnect

See scripts/arch_utils.py for reusable utility functions.

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