feat: 树渲染改用 apple/fattree 模型，修复 Cesium alpha 抠图丢失
tree_style 新增 apple（SpeedTree Red Delicious，4475 tris，alpha 抠图叶片 + 法线贴图）和 fattree（低面数卡通树，2238 tris，实体几何）。 高度改为按模型自身包围盒归一化到目标高度，树根落在 z=0，不再用魔数； 每棵树按序号做确定性抖动（缩放 ±14%、黄金角偏航、±3° 倾斜）， tree_row 采样高度全部相同，不抖动就是同一棵树盖章 156 次。 移除 polyhaven 样式和 island_tree_01 资产（76MB）+ ingest_tree.py： 该样式 append 的 *_LOD1 并不是完整的树，枝干只有 0.41 单位高，叶片是 挂在原点下方的平面簇，本是给源文件几何节点散布用的碎片。 Cesium 侧修三处： - make_export_material 把 Alpha 恒定写死为 1.0，叶片卡片整块导出，而 SpeedTree 图集抠掉的区域是纯黑，在 Cesium 里就是黑色色块。 - Blender 4.2 起 glTF 导出不再读 blend_method（仍可写但已失效，写 CLIP 读回来是 HASHED），改为从节点树推断 alpha 模式，alpha 直连 BSDF 会落到 BLEND。新增 materials.link_alpha_clip() 构造导出器识别的 1 - (alpha < cutoff) 结构，得到 alphaMode=MASK。 - 新增 alpha_dilated_image()：把不透明像素颜色向抠图区域外扩 8 圈， 避免 mipmap 把黑色平均进叶缘。叶缘相邻的纯黑像素 10.3% → 0.6%。 另修两个既有 bug： - 材质槽在 mesh 上，181 棵树共享一个 datablock，第一棵替换后其余会把结果 再包一层，产生 Cesium Cesium Cesium... 的材质名；烘焙图缓存按材质名索引， 每轮再嵌一份同样的贴图。GLB 22.46MB → 20.76MB，materials 270 → 23。 - shrub_02 从 glTF 带进来一个 Math 节点接在 Alpha 上，但其 JPEG 贴图 alpha 全是 1.0，只判断「连了 Alpha」会误判为抠图材质。 模型资产为第三方素材，已 gitignore，缺失时回落到 natural； 来源见 assets/models/SOURCES.md。 Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
@@ -16,6 +16,18 @@ import sys
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import bpy
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import numpy as np
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# --factory-startup does not put the script's own directory on sys.path, so the
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# osmassets package next to this file is not importable without this.
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_HERE = os.path.dirname(os.path.abspath(__file__))
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if _HERE not in sys.path:
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sys.path.insert(0, _HERE)
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from osmassets.materials import link_alpha_clip # noqa: E402
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# Marks a material this exporter produced, so a second pass over an instanced
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# mesh's shared slots can recognise its own output and leave it alone.
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EXPORT_PREFIX = "Cesium "
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EXPORT_TINTS = {
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"Grass": ((0.12, 0.48, 0.08), 0.72),
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@@ -117,6 +129,48 @@ def source_texture_scale(material):
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return (1.0, 1.0, 1.0)
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def source_alpha_clipped(material):
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"""Whether the source material carries its silhouette in a texture alpha.
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Two conditions, because either alone gives a wrong answer. A link into the
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Principled Alpha input is not enough: shrub_02 arrives from glTF with a
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Math node wired there even though its JPEG diffuse is opaque, and taking
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that at face value re-encodes an opaque texture as a PNG and makes Cesium
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alpha-test 270 tufts for nothing. An alpha channel alone is not enough
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either: fat_tree.png is RGBA with every texel at 1.0.
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So ask both — the author wired alpha, and the texture actually cuts.
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"""
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node = principled_bsdf(material)
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if not node or "Alpha" not in node.inputs:
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return False
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if not node.inputs["Alpha"].links:
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return False
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diffuse = image_for(material, want_normal=False)
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return diffuse is not None and image_has_cutout(diffuse)
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_CUTOUT_CACHE = {}
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def image_has_cutout(image, threshold=0.5):
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"""Whether any of the image's texels are transparent enough to be cut.
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A full pass over the pixel buffer, so memoise it — the exporter asks once
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per material and several materials can share one texture.
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"""
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if image.name in _CUTOUT_CACHE:
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return _CUTOUT_CACHE[image.name]
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width, height = image.size
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result = False
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if width and height:
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alpha = np.empty(width * height * 4, dtype=np.float32)
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image.pixels.foreach_get(alpha)
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result = bool((alpha[3::4] < threshold).any())
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_CUTOUT_CACHE[image.name] = result
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return result
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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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@@ -141,7 +195,57 @@ def cesium_tinted_image(material, 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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return tinted_image(
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source, f"{EXPORT_PREFIX}{safe_name} Baked", color, factor)
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def alpha_dilated_image(source, name, threshold=0.5, passes=8):
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"""Flood the opaque colour outward underneath the cut-out.
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SpeedTree writes pure black wherever a leaf card is cut away — 97% of the
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apple atlas's transparent area is exactly (0, 0, 0). An alpha mask hides
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that at full resolution, but Cesium mip-maps the texture and every mip
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level averages those black texels into the leaf edges, so the crown grows a
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dark fringe that thickens with distance. Blender's preview renders at mip
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0 and never shows it, which is why this only surfaces in the viewer.
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Replacing the colour under the cut-out with its nearest opaque neighbours
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leaves no black to bleed. Alpha is copied through untouched, so the
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silhouette is byte-for-byte what it was.
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"""
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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((height, width, 4))
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rgb = rgba[..., :3].copy()
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filled = rgba[..., 3] >= threshold
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# Each pass pushes the colour one texel further out, so `passes` is how
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# many mip levels' worth of filter footprint gets covered.
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for _ in range(passes):
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if filled.all():
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break
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weight = filled[..., None].astype(np.float32)
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total = np.zeros_like(rgb)
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count = np.zeros((height, width, 1), dtype=np.float32)
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for shift, axis in ((1, 0), (-1, 0), (1, 1), (-1, 1)):
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total += np.roll(rgb * weight, shift, axis=axis)
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count += np.roll(weight, shift, axis=axis)
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edge = (~filled) & (count[..., 0] > 0)
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rgb[edge] = total[edge] / count[edge]
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filled = filled | edge
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dilated = rgba.copy()
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dilated[..., :3] = rgb
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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(dilated.ravel())
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result.pack()
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return result
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def tree_crown_image():
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@@ -175,7 +279,7 @@ def tree_crown_image():
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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.name = EXPORT_PREFIX + 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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@@ -205,10 +309,17 @@ def make_export_material(material):
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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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# Foliage that carries its silhouette in the texture's alpha has to keep
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# that channel; every other material is flattened to opaque below.
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alpha_clipped = source_alpha_clipped(material)
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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 alpha_clipped and diffuse is not None:
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safe_name = material.name.replace(" ", "_")
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diffuse = alpha_dilated_image(
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diffuse, f"{EXPORT_PREFIX}{safe_name} Dilated")
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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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@@ -221,6 +332,7 @@ def make_export_material(material):
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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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diffuse_node = None
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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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@@ -228,6 +340,7 @@ def make_export_material(material):
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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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diffuse_node = image
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if normal:
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normal_tex = nodes.new("ShaderNodeTexImage")
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@@ -242,7 +355,14 @@ def make_export_material(material):
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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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if alpha_clipped and diffuse_node is not None:
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# A leaf crown is a handful of quads whose shape lives entirely in this
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# channel. Pinning Alpha to 1.0 — which is what the rest of the scene
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# wants — exports those quads whole, and the cut-away regions of a
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# SpeedTree atlas are black, so Cesium draws black slabs.
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link_alpha_clip(result, diffuse_node.outputs["Alpha"], bsdf,
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cutoff=material.alpha_threshold)
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elif "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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@@ -305,6 +425,14 @@ def export(args):
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if not slot.material:
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continue
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source = slot.material
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# Instanced props share one mesh datablock, and material slots live
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# on the mesh, so the first tree already swapped in the export
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# material for all 181 of them. Without this the next instance
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# wraps that result again — "Cesium Cesium Cesium ..." — and since
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# the baked-image cache is keyed by material name, every round
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# embeds another multi-megabyte copy of the same texture.
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if source.name.startswith(EXPORT_PREFIX):
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continue
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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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