fix(examples): give the swatch-grid gold something to reflect

Render path only. The mirror gold reflected the near-black world and read
as a black ball; a reflection-only sky (Light Path Is Glossy Ray) now gives
it a warm overhead gradient while camera and diffuse rays still see the
dark stage. The backdrop moves in behind the spheres so they cast contact
shadows. Six-region pixel check and exit codes unchanged on all three
binaries. Also refreshes the gallery alts and index for both examples.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

Author: TMHSDigital

docs/gallery/assets/swatch-grid-hero.webp

@@ -343,7 +343,7 @@ <h1>Examples and Showcase</h1>
     <div class="grid" id="grid">
       <article class="card" data-tags="materials rendering">
         <a class="card-media" href="swatch-grid/" tabindex="-1" aria-hidden="true">
-          <img src="assets/swatch-grid-hero.webp" alt="Six material spheres in two rows: black glossy, copper metal, red, blue, flat orange emission and white." loading="lazy" decoding="async" />
+          <img src="assets/swatch-grid-hero.webp" alt="Six material spheres in two rows against a dark backdrop: mirror gold, brushed copper, red, blue, flat orange emission and white." loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="swatch-grid/">swatch-grid</a></h2>
@@ -354,7 +354,7 @@ <h2><a href="swatch-grid/">swatch-grid</a></h2>
       </article>
       <article class="card" data-tags="animation">
         <a class="card-media" href="turntable/" tabindex="-1" aria-hidden="true">
-          <img src="assets/turntable-hero.webp" alt="A bronze monkey head (Suzanne) turned three-quarters on a dark studio floor." loading="lazy" decoding="async" />
+          <img src="assets/turntable-hero.webp" alt="A smooth copper monkey head (Suzanne) turned three-quarters on a black turntable with a brushed metal platter." loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="turntable/">turntable</a></h2>

docs/gallery/contact-sheets/swatch-grid-contact-sheet.webp

@@ -16,13 +16,13 @@
   <meta property="og:image" content="https://tmhsdigital.github.io/Blender-Developer-Tools/gallery/assets/swatch-grid-hero.webp" />
   <meta property="og:image:width" content="1280" />
   <meta property="og:image:height" content="720" />
-  <meta property="og:image:alt" content="Six material spheres in two rows: black glossy, copper metal, red, blue, flat orange emission and white." />
+  <meta property="og:image:alt" content="Six material spheres in two rows against a dark backdrop: mirror gold, brushed copper, red, blue, flat orange emission and white." />
   <meta property="og:site_name" content="Blender Developer Tools" />
   <meta name="twitter:card" content="summary_large_image" />
   <meta name="twitter:title" content="swatch-grid — Examples — Blender Developer Tools" />
   <meta name="twitter:description" content="Procedural Principled materials — metal and dielectric, the emission pattern, and the cross-version set_specular shim." />
   <meta name="twitter:image" content="https://tmhsdigital.github.io/Blender-Developer-Tools/gallery/assets/swatch-grid-hero.webp" />
-  <meta name="twitter:image:alt" content="Six material spheres in two rows: black glossy, copper metal, red, blue, flat orange emission and white." />
+  <meta name="twitter:image:alt" content="Six material spheres in two rows against a dark backdrop: mirror gold, brushed copper, red, blue, flat orange emission and white." />
   <style>
     /* fonts are deployed by the landing build (docs/fonts/) */
     @font-face { font-family: 'Barlow Condensed'; font-weight: 600; font-display: swap;
@@ -268,8 +268,8 @@ <h1>swatch-grid</h1>
     <p>Procedural Principled materials — metal and dielectric, the emission pattern, and the cross-version set_specular shim.</p>
   </header>
   <main id="main">
-    <button class="detail-hero" id="heroZoom" type="button" aria-label="View full size: Six material spheres in two rows: black glossy, copper metal, red, blue, flat orange emission and white.">
-      <img src="../assets/swatch-grid-hero.webp" alt="Six material spheres in two rows: black glossy, copper metal, red, blue, flat orange emission and white." width="1280" height="720" />
+    <button class="detail-hero" id="heroZoom" type="button" aria-label="View full size: Six material spheres in two rows against a dark backdrop: mirror gold, brushed copper, red, blue, flat orange emission and white.">
+      <img src="../assets/swatch-grid-hero.webp" alt="Six material spheres in two rows against a dark backdrop: mirror gold, brushed copper, red, blue, flat orange emission and white." width="1280" height="720" />
     </button>
     <p class="zoom-hint">Rendered headless by the example itself — click to zoom.</p>
     <div class="callout"><span class="tag">witnesses</span> EEVEE engine-id mapping: BLENDER_EEVEE on 5.x, BLENDER_EEVEE_NEXT on 4.2–4.5.</div>
@@ -294,6 +294,8 @@ <h2>Run</h2>
 # GPU-less / CI hosts: render the pixels with Cycles (CPU). The EEVEE id is still
 # asserted; only the final pixels use Cycles.
 blender --background --python swatch_grid.py -- --output swatch.png --engine cycles --samples 16 --width 960</code></pre>
+<h2>Staging</h2>
+<p>The backdrop stands 0.16 behind the spheres, so each casts a soft contact shadow. It used to stand 1.58 behind them, and the grid floated. The world is a reflection-only sky: glossy rays see a warm overhead gradient above a dark horizon, and camera and diffuse rays see the dark stage. The mirror-finish gold otherwise reflected the near-black world and rendered as a black ball with two light-card glints. Sphere positions, materials, the camera and the six-region pixel check are unchanged; <code>verify_png</code> still reads six distinct regions on 4.5.11, 5.1.2 and 5.2.1.</p>
 <h2>Exit codes</h2>
 <p>Per-script sequential checks. <code>9</code> is a valid check code; there is no rule against it. <code>10</code> is the shared framing helper.</p>
 <div class="table-wrap"><table><thead><tr><th scope="col">Code</th><th scope="col">Meaning</th></tr></thead><tbody><tr><td>0</td><td>Success</td></tr><tr><td>1</td><td>Uncaught exception (FATAL wrapper)</td></tr><tr><td>2</td><td>argparse / usage</td></tr><tr><td>3</td><td>Distinct swatch colors ≠ 6 (<code>--same-base</code> lands here); also render not six distinct regions</td></tr><tr><td>4</td><td><code>--output</code> produced no file</td></tr><tr><td>5</td><td>Wrong-era EEVEE engine id was accepted</td></tr><tr><td>10</td><td>Gallery framing violation</td></tr></tbody></table></div>
@@ -463,7 +465,10 @@ <h2>Source</h2>
     wmat, _ = make_principled(<span class="s">&quot;Studio&quot;</span>, (<span class="n">0.03</span>, <span class="n">0.032</span>, <span class="n">0.037</span>, <span class="n">1</span>), <span class="n">0.0</span>, <span class="n">0.7</span>)
     wall_me.materials.append(wmat)
     wall = bpy.data.objects.new(<span class="s">&quot;Wall&quot;</span>, wall_me)
-    wall.location = (<span class="n">0.0</span>, <span class="n">2.5</span>, <span class="n">0.0</span>)
+    <span class="c"># just behind the spheres (0.16 clear of their backs) so each casts a</span>
+    <span class="c"># soft contact shadow and reads as mounted; at y=2.5 they hung 1.58 in</span>
+    <span class="c"># front of the backdrop with nothing under them</span>
+    wall.location = (<span class="n">0.0</span>, <span class="n">1.08</span>, <span class="n">0.0</span>)
     wall.rotation_euler = (math.radians(<span class="n">90</span>), <span class="n">0.0</span>, <span class="n">0.0</span>)
     bpy.context.collection.objects.link(wall)
 
@@ -492,7 +497,29 @@ <h2>Source</h2>
     bpy.data.objects[<span class="s">&quot;WedgeL&quot;</span>].rotation_euler = (math.radians(-<span class="n">56</span>), <span class="n">0.0</span>, math.radians(<span class="n">190</span>))
     world = bpy.data.worlds.new(<span class="s">&quot;W&quot;</span>)
     world.use_nodes = <span class="k">True</span>
-    world.node_tree.nodes[<span class="s">&quot;Background&quot;</span>].inputs[<span class="n">0</span>].default_value = (<span class="n">0.02</span>, <span class="n">0.021</span>, <span class="n">0.025</span>, <span class="n">1</span>)
+    nt = world.node_tree
+    bg = nt.nodes[<span class="s">&quot;Background&quot;</span>]
+    bg.inputs[<span class="n">0</span>].default_value = (<span class="n">0.02</span>, <span class="n">0.021</span>, <span class="n">0.025</span>, <span class="n">1</span>)
+    <span class="c"># A reflection-only sky: glossy rays see a warm overhead gradient over a</span>
+    <span class="c"># dark horizon, every other ray the dark stage. The mirror-finish gold</span>
+    <span class="c"># otherwise reflected the near-black world and rendered as a black ball</span>
+    <span class="c"># with two light-card glints. Diffuse and camera rays are unchanged, so</span>
+    <span class="c"># the stage stays dark.</span>
+    path = nt.nodes.new(<span class="s">&quot;ShaderNodeLightPath&quot;</span>)
+    coord = nt.nodes.new(<span class="s">&quot;ShaderNodeTexCoord&quot;</span>)
+    sep = nt.nodes.new(<span class="s">&quot;ShaderNodeSeparateXYZ&quot;</span>)
+    nt.links.new(coord.outputs[<span class="s">&quot;Generated&quot;</span>], sep.inputs[<span class="n">0</span>])
+    sky = nt.nodes.new(<span class="s">&quot;ShaderNodeValToRGB&quot;</span>)
+    sky.color_ramp.elements[<span class="n">0</span>].position = <span class="n">0.0</span>
+    sky.color_ramp.elements[<span class="n">0</span>].color = (<span class="n">0.02</span>, <span class="n">0.021</span>, <span class="n">0.025</span>, <span class="n">1</span>)
+    sky.color_ramp.elements[<span class="n">1</span>].position = <span class="n">0.7</span>
+    sky.color_ramp.elements[<span class="n">1</span>].color = (<span class="n">0.70</span>, <span class="n">0.63</span>, <span class="n">0.55</span>, <span class="n">1</span>)
+    nt.links.new(sep.outputs[<span class="s">&quot;Z&quot;</span>], sky.inputs[<span class="s">&quot;Fac&quot;</span>])
+    pick = nt.nodes.new(<span class="s">&quot;ShaderNodeMixRGB&quot;</span>)
+    pick.inputs[<span class="n">1</span>].default_value = (<span class="n">0.02</span>, <span class="n">0.021</span>, <span class="n">0.025</span>, <span class="n">1</span>)
+    nt.links.new(sky.outputs[<span class="s">&quot;Color&quot;</span>], pick.inputs[<span class="n">2</span>])
+    nt.links.new(path.outputs[<span class="s">&quot;Is Glossy Ray&quot;</span>], pick.inputs[<span class="n">0</span>])
+    nt.links.new(pick.outputs[<span class="n">0</span>], bg.inputs[<span class="n">0</span>])
     bpy.context.scene.world = world
 
 
@@ -648,7 +675,7 @@ <h2>Source</h2>
   </main>
   <dialog class="lightbox" id="lightbox" aria-label="Full-size render">
     <button class="lightbox-close" type="button" autofocus>Close</button>
-    <img src="../assets/swatch-grid-hero.webp" alt="Six material spheres in two rows: black glossy, copper metal, red, blue, flat orange emission and white." />
+    <img src="../assets/swatch-grid-hero.webp" alt="Six material spheres in two rows against a dark backdrop: mirror gold, brushed copper, red, blue, flat orange emission and white." />
   </dialog>
   <footer>
     <div class="statusbar">

docs/gallery/index.html

@@ -9,7 +9,7 @@
       "name": "swatch-grid",
       "dir": "examples/swatch-grid",
       "teaches": "Procedural Principled materials — metal and dielectric, the emission pattern, and the cross-version set_specular shim.",
-      "alt": "Six material spheres in two rows: black glossy, copper metal, red, blue, flat orange emission and white.",
+      "alt": "Six material spheres in two rows against a dark backdrop: mirror gold, brushed copper, red, blue, flat orange emission and white.",
       "witnessesFix": "EEVEE engine-id mapping: BLENDER_EEVEE on 5.x, BLENDER_EEVEE_NEXT on 4.2–4.5.",
       "hero": "docs/gallery/assets/swatch-grid-hero.webp",
       "preview": "examples/swatch-grid/preview.webp",
@@ -22,7 +22,7 @@
       "name": "turntable",
       "dir": "examples/turntable",
       "teaches": "A slotted-actions Z-rotation turntable keyed through the cross-version channelbag path (get_channelbag_for_slot).",
-      "alt": "A bronze monkey head (Suzanne) turned three-quarters on a dark studio floor.",
+      "alt": "A smooth copper monkey head (Suzanne) turned three-quarters on a black turntable with a brushed metal platter.",
       "witnessesFix": "Slotted-actions boundary: ensure-helper channelbag on 5.x, strip.channelbag on 4.4/4.5.",
       "hero": "docs/gallery/assets/turntable-hero.webp",
       "preview": "examples/turntable/preview.webp",

docs/gallery/swatch-grid/index.html

@@ -34,6 +34,17 @@ blender --background --python swatch_grid.py -- --output swatch.png
 blender --background --python swatch_grid.py -- --output swatch.png --engine cycles --samples 16 --width 960
 ```
 
+## Staging
+
+The backdrop stands 0.16 behind the spheres, so each casts a soft contact
+shadow. It used to stand 1.58 behind them, and the grid floated. The world is
+a reflection-only sky: glossy rays see a warm overhead gradient above a dark
+horizon, and camera and diffuse rays see the dark stage. The mirror-finish
+gold otherwise reflected the near-black world and rendered as a black ball
+with two light-card glints. Sphere positions, materials, the camera and the
+six-region pixel check are unchanged; `verify_png` still reads six distinct
+regions on 4.5.11, 5.1.2 and 5.2.1.
+
 ## Exit codes
 
 Per-script sequential checks. `9` is a valid check code; there is no rule

examples/gallery.json

@@ -153,7 +153,10 @@ def build_scene(mats):
     wmat, _ = make_principled("Studio", (0.03, 0.032, 0.037, 1), 0.0, 0.7)
     wall_me.materials.append(wmat)
     wall = bpy.data.objects.new("Wall", wall_me)
-    wall.location = (0.0, 2.5, 0.0)
+    # just behind the spheres (0.16 clear of their backs) so each casts a
+    # soft contact shadow and reads as mounted; at y=2.5 they hung 1.58 in
+    # front of the backdrop with nothing under them
+    wall.location = (0.0, 1.08, 0.0)
     wall.rotation_euler = (math.radians(90), 0.0, 0.0)
     bpy.context.collection.objects.link(wall)
 
@@ -182,7 +185,29 @@ def build_scene(mats):
     bpy.data.objects["WedgeL"].rotation_euler = (math.radians(-56), 0.0, math.radians(190))
     world = bpy.data.worlds.new("W")
     world.use_nodes = True
-    world.node_tree.nodes["Background"].inputs[0].default_value = (0.02, 0.021, 0.025, 1)
+    nt = world.node_tree
+    bg = nt.nodes["Background"]
+    bg.inputs[0].default_value = (0.02, 0.021, 0.025, 1)
+    # A reflection-only sky: glossy rays see a warm overhead gradient over a
+    # dark horizon, every other ray the dark stage. The mirror-finish gold
+    # otherwise reflected the near-black world and rendered as a black ball
+    # with two light-card glints. Diffuse and camera rays are unchanged, so
+    # the stage stays dark.
+    path = nt.nodes.new("ShaderNodeLightPath")
+    coord = nt.nodes.new("ShaderNodeTexCoord")
+    sep = nt.nodes.new("ShaderNodeSeparateXYZ")
+    nt.links.new(coord.outputs["Generated"], sep.inputs[0])
+    sky = nt.nodes.new("ShaderNodeValToRGB")
+    sky.color_ramp.elements[0].position = 0.0
+    sky.color_ramp.elements[0].color = (0.02, 0.021, 0.025, 1)
+    sky.color_ramp.elements[1].position = 0.7
+    sky.color_ramp.elements[1].color = (0.70, 0.63, 0.55, 1)
+    nt.links.new(sep.outputs["Z"], sky.inputs["Fac"])
+    pick = nt.nodes.new("ShaderNodeMixRGB")
+    pick.inputs[1].default_value = (0.02, 0.021, 0.025, 1)
+    nt.links.new(sky.outputs["Color"], pick.inputs[2])
+    nt.links.new(path.outputs["Is Glossy Ray"], pick.inputs[0])
+    nt.links.new(pick.outputs[0], bg.inputs[0])
     bpy.context.scene.world = world