Add Preview Mesh Slicer node (interactive VTK.js clip)

3D clip view + orthographic pick view (XY/YZ/XZ toggle): click 2 points to
define a cut line swept along the view axis into a clip plane; flip clip
slices the other side. Python node exports the mesh .vtp; clipping is
interactive in viewer_slicer.html. prestartup copies the new slicer viewer.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

nodes/visualization/__init__.py

@@ -16,6 +16,7 @@ from .preview_gaussian import PreviewGaussianNode, NODE_CLASS_MAPPINGS as PREVIE
 from .preview_mesh_analysis import PreviewMeshAnalysisNode, NODE_CLASS_MAPPINGS as PREVIEW_MESH_ANALYSIS_MAPS, NODE_DISPLAY_NAME_MAPPINGS as PREVIEW_MESH_ANALYSIS_DISP
 from .render_mesh_batch import NODE_CLASS_MAPPINGS as RENDER_MESH_BATCH_MAPS, NODE_DISPLAY_NAME_MAPPINGS as RENDER_MESH_BATCH_DISP
 from .preview_mesh_boundaries import NODE_CLASS_MAPPINGS as PREVIEW_MESH_BOUNDARIES_MAPS, NODE_DISPLAY_NAME_MAPPINGS as PREVIEW_MESH_BOUNDARIES_DISP
+from .preview_mesh_slicer import NODE_CLASS_MAPPINGS as PREVIEW_MESH_SLICER_MAPS, NODE_DISPLAY_NAME_MAPPINGS as PREVIEW_MESH_SLICER_DISP
 
 NODE_CLASS_MAPPINGS = {}
 NODE_DISPLAY_NAME_MAPPINGS = {}
@@ -42,5 +43,7 @@ NODE_CLASS_MAPPINGS.update(RENDER_MESH_BATCH_MAPS)
 NODE_DISPLAY_NAME_MAPPINGS.update(RENDER_MESH_BATCH_DISP)
 NODE_CLASS_MAPPINGS.update(PREVIEW_MESH_BOUNDARIES_MAPS)
 NODE_DISPLAY_NAME_MAPPINGS.update(PREVIEW_MESH_BOUNDARIES_DISP)
+NODE_CLASS_MAPPINGS.update(PREVIEW_MESH_SLICER_MAPS)
+NODE_DISPLAY_NAME_MAPPINGS.update(PREVIEW_MESH_SLICER_DISP)
 
 __all__ = ['NODE_CLASS_MAPPINGS', 'NODE_DISPLAY_NAME_MAPPINGS']

nodes/visualization/preview_mesh_slicer.py

@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+# Copyright (C) 2025 ComfyUI-GeometryPack Contributors
+
+"""
+Preview Mesh Slicer - interactive VTK.js clip/slice preview.
+
+Top: 3D view of the mesh with a live clipping plane. Bottom: an orthographic
+pick view (toggle XY / YZ / XZ); click two points to define a cut line, which is
+swept along the view axis into a clip plane. "Flip clip" slices the other side.
+
+The Python node just exports the mesh to a .vtp; all the clipping is interactive
+in the browser (viewer_slicer.html).
+"""
+
+import logging
+import os
+import uuid
+
+from comfy_api.latest import io
+
+log = logging.getLogger("geometrypack")
+
+
+class PreviewMeshSlicer(io.ComfyNode):
+    """Interactive clip/slice preview of a mesh in VTK.js."""
+
+    @classmethod
+    def define_schema(cls):
+        return io.Schema(
+            node_id="GeomPackPreviewMeshSlicer",
+            display_name="Preview Mesh Slicer",
+            category="geompack/visualization",
+            is_output_node=True,
+            inputs=[
+                io.Custom("TRIMESH").Input("mesh", tooltip="Mesh to slice/clip interactively."),
+            ],
+            outputs=[],
+        )
+
+    @classmethod
+    def execute(cls, mesh):
+        import folder_paths
+        from ._vtp_export import export_mesh_with_scalars_vtp
+
+        tmp = folder_paths.get_temp_directory()
+        os.makedirs(tmp, exist_ok=True)
+        filename = f"gp_slicer_{uuid.uuid4().hex[:8]}.vtp"
+        export_mesh_with_scalars_vtp(mesh, os.path.join(tmp, filename))
+
+        nv = len(getattr(mesh, "vertices", []))
+        nf = len(getattr(mesh, "faces", []))
+        log.info("[PreviewMeshSlicer] exported %s (%d verts, %d faces)", filename, nv, nf)
+        return io.NodeOutput(ui={
+            "mesh_file": [filename],
+            "summary": [f"{nv:,} verts / {nf:,} faces — slice interactively in the viewer"],
+        })
+
+
+NODE_CLASS_MAPPINGS = {"GeomPackPreviewMeshSlicer": PreviewMeshSlicer}
+NODE_DISPLAY_NAME_MAPPINGS = {"GeomPackPreviewMeshSlicer": "Preview Mesh Slicer"}

prestartup_script.py

@@ -24,6 +24,7 @@ viewers = [
     "bvh", "fbx_animation", "compare_smpl_bvh",
     "text_report",
     "ultimate_inspection",
+    "slicer",
 ]
 for viewer in viewers:
     try:

web_src/preview_mesh_slicer.js

@@ -0,0 +1,63 @@
+// Preview Mesh Slicer: interactive clip/slice viewer (viewer_slicer.html) in-node.
+// On execute the Python node writes the mesh .vtp to temp; we mount the slicer
+// iframe and postMessage it the file URL.
+import { app } from "../../../scripts/app.js";
+
+const TAG = "[PreviewMeshSlicer]";
+console.log(`${TAG} script loaded`);
+
+const EXTENSION_FOLDER = (() => {
+    const m = import.meta.url.match(/\/extensions\/([^/]+)\//);
+    return m ? m[1] : "ComfyUI-GeometryPack";
+})();
+
+function viewUrl(name) {
+    const norm = String(name).replace(/\\/g, "/");
+    const m = norm.match(/(?:^|\/)(output|input|temp)\/(.+)$/);
+    if (m) {
+        const [, type, rel] = m;
+        const parts = rel.split("/");
+        const fname = parts.pop();
+        return `/view?filename=${encodeURIComponent(fname)}&type=${type}&subfolder=${encodeURIComponent(parts.join("/"))}`;
+    }
+    return `/view?filename=${encodeURIComponent(norm.split("/").pop())}&type=temp&subfolder=`;
+}
+
+app.registerExtension({
+    name: "geompack.previewmeshslicer",
+    async beforeRegisterNodeDef(nodeType, nodeData) {
+        if (nodeData.name !== "GeomPackPreviewMeshSlicer") return;
+        console.log(`${TAG} registering for GeomPackPreviewMeshSlicer`);
+
+        const onCreated = nodeType.prototype.onNodeCreated;
+        nodeType.prototype.onNodeCreated = function () {
+            const r = onCreated?.apply(this, arguments);
+            const node = this;
+            const iframe = document.createElement("iframe");
+            iframe.style.cssText = "width:100%;height:100%;border:none;background:#2a2a2a;";
+            iframe.src = `/extensions/${EXTENSION_FOLDER}/viewer_slicer.html?v=` + Date.now();
+            const widget = node.addDOMWidget("slicer", "MESH_PREVIEW", iframe, {
+                getValue() { return ""; }, setValue() { },
+            });
+            widget.computeSize = (w) => [w || 480, Math.round((w || 480) * 1.15)];
+            node.size = [Math.max(node.size?.[0] || 0, 420), Math.max(node.size?.[1] || 0, 540)];
+            node._gpSlicerIframe = iframe;
+            return r;
+        };
+
+        const onExecuted = nodeType.prototype.onExecuted;
+        nodeType.prototype.onExecuted = function (message) {
+            onExecuted?.apply(this, arguments);
+            const iframe = this._gpSlicerIframe;
+            const name = message?.mesh_file?.[0];
+            if (!iframe || !name) return;
+            const url = viewUrl(name);
+            setTimeout(() => {
+                if (iframe.contentWindow) {
+                    console.log(`${TAG} loading ${url}`);
+                    iframe.contentWindow.postMessage({ type: "LOAD_MESH", filepath: url, timestamp: Date.now() }, "*");
+                }
+            }, 250);
+        };
+    },
+});