Add numbered markers (S1, S2…) for cross-section positions on orthographic views

app.py

@@ -122,6 +122,7 @@ def _selection_path(filename):
     "front_flip": False,
     "output_format": "png",
     "label_parts": False,
+    "label_sections": False,
     "ao_mode": "ssao",
     "keep_uploads": False,
 }
@@ -301,6 +302,7 @@ def stream():
             front_flip = bool(data.get("front_flip", False))
             rotation_deg = float(data.get("rotation_deg", 0) or 0)
             label_parts = bool(data.get("label_parts", False))
+            label_sections = bool(data.get("label_sections", False))
             keep_uploads = bool(data.get("keep_uploads", False))
             # "vertex" (fast: per-vertex baked AO, can look blocky on large
             # flat panels) or "ssao" (default: screen-space AO computed
@@ -324,6 +326,7 @@ def stream():
                 "ao": ao_enabled, "ao_darkness": ao_darkness, "up_axis": up_axis,
                 "front_flip": front_flip, "rotation_deg": rotation_deg,
                 "output_format": output_format, "label_parts": label_parts,
+                "label_sections": label_sections,
                 "ao_mode": ao_mode, "keep_uploads": keep_uploads,
             })
 
@@ -425,6 +428,7 @@ def stream():
                 bg_color=bg_color, line_color=line_color, scale_pct=scale_pct,
                 model_name=model_display_name,
                 part_numbers=(part_numbers if label_parts else None),
+                label_sections=label_sections,
             )
             yield _event("Done.", 1.0, done=True, image_url=f"/outputs/{out_name}")
 

compositor.py

@@ -146,14 +146,20 @@ def _draw_view(ax, result, bbox, line_color, bg_color="#FFFFFF",
         # pixel regardless of where along the axis it actually is), so a
         # cut position has no meaningful line to draw there at all —
         # callers simply don't pass markers for those views.
-        for frac in (rib_marker_x_fracs or []):
+        for frac, num in (rib_marker_x_fracs or []):
             x = xmin + frac * (xmax - xmin)
             ax.plot([x, x], [ymin, ymax], linestyle=(0, (2, 4)), linewidth=0.5,
                     color=line_color, alpha=0.35, zorder=1, solid_capstyle="butt")
-        for frac in (rib_marker_y_fracs or []):
+            if num is not None:
+                ax.text(x, ymin + (ymax - ymin) * 0.02, f"S{num}", ha="center", va="top",
+                        fontsize=18 * cs, family="DejaVu Sans", color=line_color, alpha=0.85, zorder=1)
+        for frac, num in (rib_marker_y_fracs or []):
             y = ymin + frac * (ymax - ymin)
             ax.plot([xmin, xmax], [y, y], linestyle=(0, (2, 4)), linewidth=0.5,
                     color=line_color, alpha=0.35, zorder=1, solid_capstyle="butt")
+            if num is not None:
+                ax.text(xmin + (xmax - xmin) * 0.01, y, f"S{num}", ha="left", va="center",
+                        fontsize=18 * cs, family="DejaVu Sans", color=line_color, alpha=0.85, zorder=1)
 
     outer_segs = [np.column_stack([c[:, 1], c[:, 0]]) for c in result["outer_contours"]]
     if outer_segs:
@@ -258,7 +264,8 @@ def _draw_rib(ax, rib_segments, ppm, bbox, line_color, lw=1.0):
 def compose_image(view_results, rib_sections, rib_ppm, output_path,
                    bg_color="#FFFFFF", line_color="#000000",
                    scale_pct=100, dpi_base=250,
-                   model_name=None, show_chrome=True, part_numbers=None):
+                   model_name=None, show_chrome=True, part_numbers=None,
+                   label_sections=True):
     """view_results: dict of {view_name: render_view() result}, only for
     views the user actually requested.
     rib_sections: list of rib cuts, each a list of (p0,p1) segment pairs
@@ -424,7 +431,11 @@ def add_axes_px(x0, y0_top, wpx, hpx):
                 w_v, h_v = sizes[name]
                 ax = add_axes_px(x_cursor, y_cursor, w_v, view_row_h)
                 axis_kind, mirrored = _RIB_MARKER_AXIS.get(name, (None, False))
-                fracs_for_view = [(1 - f if mirrored else f) for f in rib_fracs] if axis_kind else []
+                fracs_for_view = (
+                    [(1 - f if mirrored else f, (i + 1) if (show_chrome and label_sections) else None)
+                     for i, f in enumerate(rib_fracs)]
+                    if axis_kind else []
+                )
                 _draw_view(
                     ax, view_results[name], bboxes[name], line_color, bg_color,
                     label=(name.upper() if show_chrome else None),

templates/index.html

@@ -112,6 +112,19 @@ <h1>Orthographic Template Generator</h1>
   }
 
   document.addEventListener('DOMContentLoaded', updateThemeToggleLabel);
+
+  function updateLabelSectionsState() {
+    var ribChecked = document.getElementById('rib_cb').checked;
+    var cb = document.getElementById('label_sections_cb');
+    if (!ribChecked) {
+      cb.checked = false;
+      cb.disabled = true;
+    } else {
+      cb.disabled = false;
+    }
+  }
+
+  document.addEventListener('DOMContentLoaded', updateLabelSectionsState);
 </script>
 
 <div class="section">
@@ -161,6 +174,9 @@ <h2>3. Views</h2>
     <span id="rib_cuts_val">1</span>
     <span style="color:#666;font-size:0.85em;">(1 = single cut at the midpoint. Higher = more evenly-spaced cuts)</span>
   </div>
+  <div class="color_row" style="margin-top:6px;">
+    <label><input type="checkbox" id="label_sections_cb"> Number cross-section markers on views (S1, S2…)</label>
+  </div>
 
   <h2 style="margin-top:20px;">3b. Orientation (only touch if the model loads facing the wrong way)</h2>
   <div class="color_row">
@@ -285,6 +301,8 @@ <h2 style="margin-top:20px;">5. Detail &amp; Output</h2>
   document.getElementById('rotation_deg_input').value = prefs.rotation_deg || 0;
   document.getElementById('output_format_select').value = prefs.output_format || 'png';
   document.getElementById('label_parts_cb').checked = !!prefs.label_parts;
+  document.getElementById('label_sections_cb').checked = !!prefs.label_sections;
+  updateLabelSectionsState();
   document.getElementById('keep_uploads_cb').checked = !!prefs.keep_uploads;
 }
 
@@ -293,6 +311,8 @@ <h2 style="margin-top:20px;">5. Detail &amp; Output</h2>
   .then(prefs => applyGlobalPrefs(prefs))
   .catch(() => {});  // non-fatal if this fails; controls just keep their defaults
 
+document.getElementById('rib_cb').addEventListener('change', updateLabelSectionsState);
+
 dropZone.addEventListener('click', () => fileInput.click());
 dropZone.addEventListener('dragover', e => { e.preventDefault(); dropZone.classList.add('dragover'); });
 dropZone.addEventListener('dragleave', () => dropZone.classList.remove('dragover'));
@@ -422,6 +442,7 @@ <h2 style="margin-top:20px;">5. Detail &amp; Output</h2>
     rotation_deg: parseFloat(document.getElementById('rotation_deg_input').value) || 0,
     output_format: document.getElementById('output_format_select').value,
     label_parts: document.getElementById('label_parts_cb').checked,
+    label_sections: document.getElementById('label_sections_cb').checked,
     keep_uploads: document.getElementById('keep_uploads_cb').checked,
   };