Add lighting gallery examples and update docs

Gallery: colored point lights scene, spotlight scene with hotspot/falloff.
CHANGES.md: document all light types, multi-light, decay, spot cone.
Docs: expand 3D Materials section with light types, multi-light examples.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: leifericf

CHANGES.md

@@ -36,11 +36,19 @@
 - Add `eido.ir.vary` with override descriptors (by-index, by-position, by-noise, by-gradient)
 - Generators accept vary descriptors in `:generator/overrides`
 
-### 3D materials
+### 3D materials and lighting
 
 - Add `eido.ir.material` with Blinn-Phong material descriptors (ambient, diffuse, specular, shininess)
-- Extend `scene3d/shade-face-style` to support `:material` key with specular highlights
-- Backward compatible — existing scenes without `:material` unchanged
+- Add four light types inspired by 3ds Max: directional, omni (point), spot, hemisphere (sky)
+- Light constructors: `material/directional`, `material/omni`, `material/spot`, `material/hemisphere`
+- Multi-light support: `:lights` vector on render-mesh opts, contributions sum per-channel
+- Light color tinting: each light's color modulates its diffuse and specular contribution
+- Distance decay: `:none`, `:inverse`, `:inverse-square` with configurable `:light/decay-start`
+- Spot light cone: `:light/hotspot` (inner angle) and `:light/falloff` (outer angle) with smoothstep
+- Hemisphere light: sky/ground color blended by surface normal direction
+- `smoothstep` added to `eido.math3d`
+- Extend `scene3d/shade-face-style` to support materials and multi-light
+- Backward compatible — existing scenes without `:material` or `:lights` unchanged
 
 ### Multi-pass rendering
 

examples/gallery/scenes_3d.clj

@@ -436,6 +436,75 @@
                  :material (material/phong :specular 0.9 :shininess 256.0)}
          :light light})]}))
 
+;; --- 17. Colored Point Lights ---
+
+(defn ^{:example {:output "3d-colored-lights.png"
+                  :title  "Colored Point Lights"
+                  :desc   "A sphere lit by warm and cool omni lights with hemisphere ambient."}}
+  colored-point-lights []
+  (let [mesh (s3d/sphere-mesh 1.5 24 16)
+        proj (s3d/perspective {:scale 120 :origin [200 200]
+                               :yaw 0.3 :pitch -0.25 :distance 6})]
+    {:image/size [400 400]
+     :image/background [:color/rgb 15 15 20]
+     :image/nodes
+     [(s3d/render-mesh proj mesh
+        {:style {:style/fill [:color/rgb 200 200 200]
+                 :material (material/phong :ambient 0.05 :diffuse 0.8
+                                           :specular 0.5 :shininess 48.0)}
+         :lights [(material/omni [3 2 2]
+                    :color [:color/rgb 255 180 100]
+                    :multiplier 1.5
+                    :decay :inverse :decay-start 2.0)
+                  (material/omni [-3 1 -1]
+                    :color [:color/rgb 80 130 255]
+                    :multiplier 1.2
+                    :decay :inverse :decay-start 2.0)
+                  (material/hemisphere
+                    [:color/rgb 40 50 80]
+                    [:color/rgb 15 10 5]
+                    :multiplier 0.15)]})]}))
+
+;; --- 18. Spotlight Scene ---
+
+(defn ^{:example {:output "3d-spotlight.png"
+                  :title  "Spotlight"
+                  :desc   "A spot light with visible hotspot and falloff on a sphere and floor."}}
+  spotlight-scene []
+  (let [sphere (s3d/sphere-mesh 1.0 20 12)
+        floor  (s3d/cube-mesh [-3 -1.5 -3] 6)
+        proj   (s3d/perspective {:scale 80 :origin [200 220]
+                                 :yaw 0.4 :pitch -0.35 :distance 8})]
+    {:image/size [400 400]
+     :image/background [:color/rgb 10 10 15]
+     :image/nodes
+     [(s3d/render-mesh proj
+        (s3d/scale-mesh floor [1.0 0.05 1.0])
+        {:style {:style/fill [:color/rgb 180 180 180]
+                 :material (material/phong :ambient 0.02 :diffuse 0.8 :specular 0.1)}
+         :lights [(material/spot [0 8 0] [0 -1 0]
+                    :color [:color/rgb 255 240 200]
+                    :multiplier 2.0
+                    :hotspot 20 :falloff 30
+                    :decay :inverse :decay-start 3.0)
+                  (material/hemisphere
+                    [:color/rgb 20 25 40]
+                    [:color/rgb 5 5 5]
+                    :multiplier 0.1)]})
+      (s3d/render-mesh proj sphere
+        {:style {:style/fill [:color/rgb 200 60 60]
+                 :material (material/phong :ambient 0.02 :diffuse 0.7
+                                           :specular 0.6 :shininess 64.0)}
+         :lights [(material/spot [0 8 0] [0 -1 0]
+                    :color [:color/rgb 255 240 200]
+                    :multiplier 2.0
+                    :hotspot 20 :falloff 30
+                    :decay :inverse :decay-start 3.0)
+                  (material/hemisphere
+                    [:color/rgb 20 25 40]
+                    [:color/rgb 5 5 5]
+                    :multiplier 0.1)]})]}))
+
 (comment
   ;; Evaluate individual examples at the REPL:
   (utah-teapot)
@@ -453,4 +522,6 @@
   (wireframe-overlay)
   (specular-spheres)
   (glossy-torus)
-  (material-showcase))
+  (material-showcase)
+  (colored-point-lights)
+  (spotlight-scene))

examples/site/pages.clj

@@ -727,7 +727,37 @@
                        :shininess 32.0)}
    :light {:light/direction [1 2 1]
            :light/ambient 0.2
-           :light/intensity 0.8}})"]]]}
+           :light/intensity 0.8}})"]]
+       [:h4 "Light Types"]
+       [:pre [:code
+              ";; Directional — parallel rays (like the sun)
+(material/directional [1 2 1] :multiplier 0.8 :ambient 0.2)
+
+;; Omni — point light radiating in all directions
+(material/omni [100 50 200]
+  :color [:color/rgb 255 200 150]
+  :decay :inverse-square :decay-start 10.0)
+
+;; Spot — cone with hotspot/falloff angles
+(material/spot [0 200 0] [0 -1 0]
+  :hotspot 25 :falloff 35 :decay :inverse)
+
+;; Hemisphere — sky/ground ambient
+(material/hemisphere
+  [:color/rgb 135 180 220] [:color/rgb 40 30 20]
+  :multiplier 0.3)"]]
+       [:h4 "Multi-Light"]
+       [:p "Use " [:code ":lights"] " to combine multiple lights. Each light's color tints its contribution."]
+       [:pre [:code
+              "(s3d/render-mesh proj mesh
+  {:style {:style/fill [:color/rgb 200 200 200]
+           :material (material/phong :specular 0.5)}
+   :lights [(material/omni [3 2 2]
+              :color [:color/rgb 255 180 100]
+              :multiplier 1.5 :decay :inverse)
+            (material/hemisphere
+              [:color/rgb 40 50 80] [:color/rgb 15 10 5]
+              :multiplier 0.2)]})"]]]}
 
      {:id    "multi-pass"
       :title "Multi-Pass Rendering"