docs: clarify mesh selection silhouette highlighting

docs/CAMERAS_AND_LIGHTS/scene-selection-outline.md

@@ -5,10 +5,15 @@
 In the editor Scene viewport, select a mesh to display its orange outline, then
 orbit the camera around it. The outline should remain a narrow border when the
 camera lines up with any object axis. No material or script setup is required.
+The mesh keeps its shaded surface colors while selected; orange appears around
+its visible silhouette, including holes, rather than filling its faces. Geometry
+in front of the selection still hides the outline.
 
 The current renderer expands a back-face mesh shell using camera depth and viewport
 resolution, targeting roughly three pixels of padding along each object axis.
 Nonuniform object scale is accounted for in world space. This is an approximate
 outline: corners, perspective across large meshes, and irregular mesh shapes can
-vary in thickness. If a selection fills the viewport with orange at a particular
+vary in thickness. Visible selected surfaces are masked before the shell is drawn
+so concave or overlapping parts cannot paint orange across the selected faces.
+If a selection fills the viewport with orange at a particular
 orbit angle, that is a rendering fault; it is not an outline or material setting.