373 lines
13 KiB
Python
373 lines
13 KiB
Python
"""Export a Blender scene (from generate_scene.py) as a Cesium-ready GLB.
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The authoring scene intentionally uses a few Blender-only nodes (for example
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the grass tint and procedural tree crown variation). glTF has a smaller
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material vocabulary, so this exporter creates temporary, export-only PBR
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materials, unwraps the meshes, and embeds all referenced images in the GLB.
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The model remains in a local ENU frame: X east, Y north, Z up. Use the
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companion JSON file to place the GLB with Cesium.Transforms.eastNorthUpToFixedFrame.
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"""
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import json
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import os
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import sys
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import bpy
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import numpy as np
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EXPORT_TINTS = {
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"Grass": ((0.12, 0.48, 0.08), 0.72),
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"Tree Crown Dark": ((0.06, 0.22, 0.05), 0.18),
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"Tree Crown Light": ((0.16, 0.42, 0.09), 0.16),
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"Scrub Ground Cover": ((0.08, 0.28, 0.07), 0.28),
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"Office White Plaster Facade": ((0.92, 0.94, 0.92), 0.38),
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"Office White Metal Facade": ((0.92, 0.94, 0.92), 0.68),
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"Office Light Flat Roof": ((0.82, 0.86, 0.88), 0.35),
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"Industrial White Ribbed Facade": ((0.90, 0.93, 0.91), 0.86),
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"Factory Blue Metal Roof": ((0.08, 0.50, 0.88), 0.58),
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}
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EXPORT_METALLIC_OVERRIDES = {
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"Office White Plaster Facade": 0.0,
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"Office White Metal Facade": 0.0,
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"Industrial White Ribbed Facade": 0.08,
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}
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EXPORT_BASE_COLOR_OVERRIDES = {
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"Tree Crown": (0.11, 0.34, 0.075),
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"Tree Crown Dark": (0.065, 0.24, 0.055),
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"Tree Crown Light": (0.14, 0.40, 0.085),
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"Office White Plaster Facade": (0.93, 0.94, 0.91),
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"Office White Metal Facade": (0.93, 0.94, 0.91),
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"Office Light Flat Roof": (0.88, 0.90, 0.88),
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}
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EXPORT_EMISSION_OVERRIDES = {
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"Tree Crown": ((0.04, 0.11, 0.035), 0.02),
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"Tree Crown Dark": ((0.025, 0.07, 0.02), 0.015),
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"Tree Crown Light": ((0.045, 0.12, 0.03), 0.015),
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"Office White Plaster Facade": ((0.93, 0.94, 0.91), 0.18),
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"Office White Metal Facade": ((0.93, 0.94, 0.91), 0.18),
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"Office Light Flat Roof": ((0.88, 0.90, 0.88), 0.14),
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"Industrial White Ribbed Facade": ((0.90, 0.93, 0.91), 0.18),
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"Factory Blue Metal Roof": ((0.08, 0.50, 0.88), 0.12),
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}
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def cli_args():
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values = {"blend": None, "glb": None, "metadata": None}
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argv = sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []
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i = 0
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while i < len(argv):
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if argv[i].startswith("--") and i + 1 < len(argv):
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values[argv[i][2:]] = argv[i + 1]
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i += 2
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else:
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i += 1
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if not values.get("blend"):
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raise RuntimeError("--blend is required")
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if not values.get("glb"):
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raise RuntimeError("--glb is required")
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if not values.get("metadata"):
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raise RuntimeError("--metadata is required")
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return values
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def image_for(material, want_normal=False):
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candidates = []
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for node in material.node_tree.nodes:
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if node.type != "TEX_IMAGE" or not node.image:
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continue
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name = os.path.basename(node.image.name).lower()
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is_normal = "_nor_" in name or "_normal" in name or "_bump" in name
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if is_normal == want_normal:
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candidates.append(node.image)
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return candidates[0] if candidates else None
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def source_color(material):
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color = tuple(material.diffuse_color[:3])
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if len(color) != 3:
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return (0.5, 0.5, 0.5)
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return color
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def principled_bsdf(material):
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if not material.use_nodes:
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return None
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for node in material.node_tree.nodes:
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if node.type == "BSDF_PRINCIPLED":
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return node
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return None
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def source_principled_value(material, input_name, fallback):
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node = principled_bsdf(material)
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if not node or input_name not in node.inputs:
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return fallback
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return node.inputs[input_name].default_value
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def source_texture_scale(material):
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for node in material.node_tree.nodes:
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if node.type == "MAPPING":
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return tuple(node.inputs["Scale"].default_value[:3])
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return (1.0, 1.0, 1.0)
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def tinted_image(source, name, tint, factor):
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existing = bpy.data.images.get(name)
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if existing:
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return existing
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width, height = source.size
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pixels = np.empty(width * height * 4, dtype=np.float32)
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source.pixels.foreach_get(pixels)
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rgba = pixels.reshape((-1, 4))
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rgba[:, :3] = rgba[:, :3] * (1.0 - factor) + np.asarray(
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tint, dtype=np.float32) * factor
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result = bpy.data.images.new(name, width=width, height=height, alpha=True)
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result.file_format = "PNG"
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result.colorspace_settings.name = "sRGB"
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result.pixels.foreach_set(pixels)
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result.pack()
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return result
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def cesium_tinted_image(material, source):
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tint = EXPORT_TINTS.get(material.name)
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if not tint or not source:
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return source
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color, factor = tint
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safe_name = material.name.replace(" ", "_")
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return tinted_image(source, f"Cesium {safe_name} Baked", color, factor)
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def tree_crown_image():
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name = "Cesium Tree Crown Baked"
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existing = bpy.data.images.get(name)
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if existing:
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return existing
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size = 256
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x, y = np.meshgrid(
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np.linspace(0.0, 1.0, size, dtype=np.float32),
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np.linspace(0.0, 1.0, size, dtype=np.float32),
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)
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noise = (
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np.sin((x * 17.0 + y * 7.0) * np.pi) * 0.24 +
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np.sin((x * 43.0 - y * 31.0) * np.pi) * 0.13 +
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np.sin((x * 89.0 + y * 67.0) * np.pi) * 0.07
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)
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noise = np.clip(0.5 + noise, 0.0, 1.0)[..., None]
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dark = np.asarray((0.04, 0.17, 0.04), dtype=np.float32)
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light = np.asarray((0.17, 0.46, 0.115), dtype=np.float32)
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rgb = dark + (light - dark) * noise
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rgba = np.concatenate(
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(rgb, np.ones((size, size, 1), dtype=np.float32)), axis=2)
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result = bpy.data.images.new(name, width=size, height=size, alpha=True)
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result.file_format = "PNG"
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result.colorspace_settings.name = "sRGB"
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result.pixels.foreach_set(rgba.ravel())
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result.pack()
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return result
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def make_export_material(material):
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result = material.copy()
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result.name = "Cesium " + material.name
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result.use_nodes = True
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nodes = result.node_tree.nodes
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links = result.node_tree.links
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nodes.clear()
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output = nodes.new("ShaderNodeOutputMaterial")
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output.location = (520, 0)
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bsdf = nodes.new("ShaderNodeBsdfPrincipled")
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bsdf.location = (250, 0)
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base_color = EXPORT_BASE_COLOR_OVERRIDES.get(
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material.name, source_color(material))
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bsdf.inputs["Base Color"].default_value = (*base_color, 1.0)
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bsdf.inputs["Roughness"].default_value = source_principled_value(
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material, "Roughness", 0.8)
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bsdf.inputs["Metallic"].default_value = EXPORT_METALLIC_OVERRIDES.get(
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material.name, source_principled_value(material, "Metallic", 0.0))
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emission = EXPORT_EMISSION_OVERRIDES.get(material.name)
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if emission:
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emission_color, emission_strength = emission
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if "Emission Color" in bsdf.inputs:
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bsdf.inputs["Emission Color"].default_value = (*emission_color, 1.0)
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elif "Emission" in bsdf.inputs:
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bsdf.inputs["Emission"].default_value = (*emission_color, 1.0)
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if "Emission Strength" in bsdf.inputs:
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bsdf.inputs["Emission Strength"].default_value = emission_strength
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links.new(bsdf.outputs["BSDF"], output.inputs["Surface"])
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diffuse = image_for(material, want_normal=False)
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normal = image_for(material, want_normal=True)
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if material.name == "Tree Crown":
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diffuse = tree_crown_image()
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else:
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diffuse = cesium_tinted_image(material, diffuse)
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if material.name in EXPORT_BASE_COLOR_OVERRIDES:
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diffuse = None
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normal = None
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mapping = None
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if diffuse or normal:
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texcoord = nodes.new("ShaderNodeTexCoord")
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texcoord.location = (-650, 0)
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mapping = nodes.new("ShaderNodeMapping")
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mapping.location = (-450, 0)
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mapping.inputs["Scale"].default_value = source_texture_scale(material)
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links.new(texcoord.outputs["UV"], mapping.inputs["Vector"])
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if diffuse:
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image = nodes.new("ShaderNodeTexImage")
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image.location = (-200, 80)
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image.image = diffuse
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image.extension = "REPEAT"
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links.new(mapping.outputs["Vector"], image.inputs["Vector"])
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links.new(image.outputs["Color"], bsdf.inputs["Base Color"])
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if normal:
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normal_tex = nodes.new("ShaderNodeTexImage")
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normal_tex.location = (-200, -180)
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normal_tex.image = normal
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normal_tex.image.colorspace_settings.name = "Non-Color"
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normal_tex.extension = "REPEAT"
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normal_map = nodes.new("ShaderNodeNormalMap")
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normal_map.location = (20, -160)
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normal_map.inputs["Strength"].default_value = 0.52
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links.new(mapping.outputs["Vector"], normal_tex.inputs["Vector"])
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links.new(normal_tex.outputs["Color"], normal_map.inputs["Color"])
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links.new(normal_map.outputs["Normal"], bsdf.inputs["Normal"])
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if "Alpha" in bsdf.inputs:
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bsdf.inputs["Alpha"].default_value = 1.0
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return result
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def unwrap_mesh(obj):
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if obj.type != "MESH" or not obj.data.polygons:
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return
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bpy.ops.object.select_all(action="DESELECT")
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obj.select_set(True)
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bpy.context.view_layer.objects.active = obj
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bpy.ops.object.mode_set(mode="EDIT")
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bpy.ops.mesh.select_all(action="SELECT")
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try:
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bpy.ops.uv.smart_project(island_margin=0.025, area_weight=0.0)
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finally:
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bpy.ops.object.mode_set(mode="OBJECT")
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def apply_mesh_modifiers(obj):
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if obj.type != "MESH":
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return
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bpy.ops.object.select_all(action="DESELECT")
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obj.select_set(True)
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bpy.context.view_layer.objects.active = obj
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for modifier in list(obj.modifiers):
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try:
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bpy.ops.object.modifier_apply(modifier=modifier.name)
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except RuntimeError:
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pass
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def export(args):
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if not os.path.exists(args["blend"]):
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raise FileNotFoundError(args["blend"])
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bpy.ops.wm.open_mainfile(filepath=args["blend"])
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material_map = {}
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meshes = []
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for obj in bpy.context.scene.objects:
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if obj.type != "MESH":
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continue
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if obj.name == "Ground Plane":
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continue
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if obj.hide_viewport or obj.hide_render:
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continue
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meshes.append(obj)
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apply_mesh_modifiers(obj)
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unwrap_mesh(obj)
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for slot in obj.material_slots:
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if not slot.material:
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continue
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source = slot.material
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if source.name not in material_map:
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material_map[source.name] = make_export_material(source)
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slot.material = material_map[source.name]
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bpy.ops.object.select_all(action="DESELECT")
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for obj in meshes:
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obj.select_set(True)
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bpy.context.view_layer.objects.active = meshes[0] if meshes else None
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os.makedirs(os.path.dirname(args["glb"]), exist_ok=True)
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bpy.ops.export_scene.gltf(
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filepath=args["glb"],
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export_format="GLB",
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use_selection=True,
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export_apply=False,
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export_texcoords=True,
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export_normals=True,
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export_materials="EXPORT",
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export_image_format="AUTO",
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export_extras=True,
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export_cameras=False,
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export_lights=False,
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)
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scene = bpy.context.scene
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try:
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bounds = json.loads(scene.get("osm_bounds", "{}"))
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except (TypeError, ValueError):
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bounds = {}
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if bounds:
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center_lon = (bounds["min_lon"] + bounds["max_lon"]) / 2.0
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center_lat = (bounds["min_lat"] + bounds["max_lat"]) / 2.0
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else:
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center_lon = center_lat = 0.0
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metadata = {
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"asset": os.path.basename(args["glb"]),
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"coordinate_system": "local ENU meters (X east, Y north, Z up)",
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"heading_correction_degrees": -90.0,
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"anchor": {"longitude": center_lon, "latitude": center_lat, "height": 0.35},
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"bounds": bounds,
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"source_osm": scene.get("source_osm", ""),
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"source_geojson": scene.get("source_geojson", ""),
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"scene_stats": {
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"buildings": scene.get("building_count", 0),
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"industrial_buildings": scene.get("industrial_building_count", 0),
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"lake_polygons": scene.get("lake_count", 0),
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"trees": scene.get("tree_count", 0),
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"grass_polygons": scene.get("grass_count", 0),
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"scrub_polygons": scene.get("scrub_count", 0),
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"fountains": scene.get("fountain_count", 0),
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},
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"cesium_js": (
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"const p = Cesium.Cartesian3.fromDegrees(" +
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f"{center_lon:.8f}, {center_lat:.8f}, 0.35);\n" +
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"const enu = Cesium.Transforms.eastNorthUpToFixedFrame(p);\n" +
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"const correction = Cesium.Matrix3.fromRotationZ(Cesium.Math.toRadians(-90.0));\n" +
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"const modelMatrix = Cesium.Matrix4.multiplyByMatrix3(enu, correction, new Cesium.Matrix4());\n" +
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"Cesium.Model.fromGltfAsync({ url: '" + os.path.basename(args["glb"]) +
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"', modelMatrix }).then(model => viewer.scene.primitives.add(model));"
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),
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}
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os.makedirs(os.path.dirname(args["metadata"]), exist_ok=True)
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with open(args["metadata"], "w", encoding="utf-8") as handle:
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json.dump(metadata, handle, ensure_ascii=False, indent=2)
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handle.write("\n")
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print("CESIUM_EXPORT_DONE", json.dumps({
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"glb": args["glb"], "metadata": args["metadata"],
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"meshes": len(meshes), "materials": len(material_map),
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"anchor": [center_lon, center_lat],
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}, ensure_ascii=True))
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if __name__ == "__main__":
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export(cli_args())
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