Sprint 2: material presets via MeshPhysicalMaterial

Add optional `preset` field (gold/chrome/glass/neon/matte/plastic) to Obj and
ExtrudeNode. Preset routes through _preset_mat_js() in realistic style; wireframe/
toon/flat style overrides still win. gold/chrome use clearcoat for polished metal,
glass uses physical transmission+ior, neon maps node.color → emissiveIntensity:2.
Existing scenes with no preset are unchanged. Add 3 FEWSHOT examples and update
SYSTEM prompt with preset field documentation.

compiler.py

@@ -69,6 +69,51 @@ def geometry_js(o: Obj) -> str:
     return "new THREE.BoxGeometry(1, 1, 1)"
 
 
+def _preset_mat_js(node) -> str | None:
+    """Return a JS material string for a named preset, or None if no preset is set.
+
+    color override: if node.color differs from the default (#88ccff), use it;
+    otherwise fall back to each preset's canonical color so it looks right out of the box.
+    For neon, node.color is the emissive glow color regardless.
+    """
+    preset = getattr(node, "preset", None)
+    if not preset:
+        return None
+    col = _col_str(node.color)
+    has_custom = node.color != "#88ccff"
+
+    if preset == "gold":
+        c = col if has_custom else _col_str("#ffd700")
+        return (f"new THREE.MeshPhysicalMaterial({{ color: {c}, "
+                f"metalness: 1.0, roughness: 0.25, clearcoat: 1.0, clearcoatRoughness: 0.1 }})")
+
+    if preset == "chrome":
+        c = col if has_custom else _col_str("#ffffff")
+        return (f"new THREE.MeshPhysicalMaterial({{ color: {c}, "
+                f"metalness: 1.0, roughness: 0.05, clearcoat: 1.0, clearcoatRoughness: 0.05 }})")
+
+    if preset == "glass":
+        return (f"new THREE.MeshPhysicalMaterial({{ color: {col}, "
+                f"metalness: 0.0, roughness: 0.05, "
+                f"transmission: 1.0, thickness: 0.5, ior: 1.5, "
+                f"transparent: true, opacity: 1.0 }})")
+
+    if preset == "neon":
+        return (f"new THREE.MeshStandardMaterial({{ "
+                f"color: new THREE.Color('#000000'), "
+                f"emissive: {col}, emissiveIntensity: 2.0 }})")
+
+    if preset == "matte":
+        return (f"new THREE.MeshStandardMaterial({{ color: {col}, "
+                f"metalness: 0.0, roughness: 0.9 }})")
+
+    if preset == "plastic":
+        return (f"new THREE.MeshPhysicalMaterial({{ color: {col}, "
+                f"metalness: 0.0, roughness: 0.4, clearcoat: 0.5, clearcoatRoughness: 0.3 }})")
+
+    return None
+
+
 def material_js(o: Obj, style: str = "realistic") -> str:
     col = _col_str(o.color)
     emi = _col_str(o.emissive)
@@ -79,6 +124,10 @@ def material_js(o: Obj, style: str = "realistic") -> str:
     if style == "flat":
         return (f"new THREE.MeshStandardMaterial({{ color: {col}, emissive: {emi}, "
                 f"metalness: {o.metalness}, roughness: {o.roughness}, flatShading: true }})")
+    # Preset overrides per-object material field in realistic mode
+    preset_mat = _preset_mat_js(o)
+    if preset_mat:
+        return preset_mat
     # realistic — honour per-object material field
     if o.material == "basic":
         return f"new THREE.MeshBasicMaterial({{ color: {col} }})"

llm.py

@@ -35,6 +35,7 @@ Schema — primitive object:
       "scale": [x, y, z],
       "color": "#RRGGBB",
       "material": "standard|basic|phong|wireframe",
+      "preset": "gold|chrome|glass|neon|matte|plastic",
       "metalness": 0.0-1.0,
       "roughness": 0.0-1.0,
       "emissive": "#RRGGBB",
@@ -54,13 +55,21 @@ For stars, badges, shields, hearts, hexagons, coins, logos, or emblems use an EX
   "depth": 0.2,
   "bevel": true,
   "color": "#RRGGBB",
-  "material": "standard",
+  "preset": "gold|chrome|glass|neon|matte|plastic",
   "metalness": 0.0-1.0,
   "roughness": 0.0-1.0,
   "emissive": "#RRGGBB",
   "position": [x, y, z]
 }
 
+Material preset notes:
+- gold/chrome: use for shiny metallic looks; color overrides the base hue
+- glass: transparent refractive; color adds a tint
+- neon: glowing edge; set color to the desired glow color
+- matte: no shine, soft diffuse
+- plastic: slight sheen, clearcoat
+Omit preset to use metalness/roughness directly.
+
 Keep scenes small (1-4 objects). Center the composition near the origin."""
 
 FEWSHOT = [
@@ -211,6 +220,50 @@ FEWSHOT = [
         ],
         "animation": {"type": "rotate", "speed": 0.5, "axis": "y"},
     })},
+    {"role": "user", "content": "a glass star badge"},
+    {"role": "assistant", "content": json.dumps({
+        "background": "#0a0a18",
+        "objects": [{
+            "type": "extrude", "shape": "star", "depth": 0.25, "bevel": True,
+            "color": "#aaddff", "preset": "glass",
+            "position": [0, 0, 0],
+        }],
+        "lights": [
+            {"type": "ambient", "intensity": 0.6},
+            {"type": "directional", "color": "#ffffff", "intensity": 2.0, "position": [5, 8, 4]},
+            {"type": "point", "color": "#88ccff", "intensity": 1.5, "position": [-3, 2, 3]},
+        ],
+        "animation": {"type": "rotate", "speed": 0.5, "axis": "y"},
+    })},
+    {"role": "user", "content": "a neon glowing shield"},
+    {"role": "assistant", "content": json.dumps({
+        "background": "#050508",
+        "objects": [{
+            "type": "extrude", "shape": "shield", "depth": 0.2, "bevel": True,
+            "color": "#ff2266", "preset": "neon",
+            "position": [0, 0, 0],
+        }],
+        "lights": [
+            {"type": "ambient", "intensity": 0.1},
+            {"type": "point", "color": "#ff2266", "intensity": 3.0, "position": [0, 1, 2]},
+        ],
+        "animation": {"type": "float", "speed": 1.0, "axis": "y"},
+    })},
+    {"role": "user", "content": "a chrome hexagon"},
+    {"role": "assistant", "content": json.dumps({
+        "background": "#1a1a2e",
+        "objects": [{
+            "type": "extrude", "shape": "hexagon", "depth": 0.3, "bevel": True,
+            "color": "#ffffff", "preset": "chrome",
+            "position": [0, 0, 0],
+        }],
+        "lights": [
+            {"type": "ambient", "intensity": 0.4},
+            {"type": "directional", "color": "#ffffff", "intensity": 2.5, "position": [4, 6, 3]},
+            {"type": "point", "color": "#88aaff", "intensity": 1.0, "position": [-3, 2, 2]},
+        ],
+        "animation": {"type": "rotate", "speed": 0.6, "axis": "y"},
+    })},
 ]
 
 _tok = None

scene.py

@@ -23,6 +23,7 @@ SHAPES = {
 }
 EXTRUDE_SHAPES = {"star", "heart", "hexagon", "badge", "shield"}
 MATERIALS = {"standard", "basic", "phong", "wireframe"}
+PRESET_NAMES = {"gold", "chrome", "glass", "neon", "matte", "plastic"}
 LIGHT_TYPES = {"ambient", "directional", "point"}
 ANIM_TYPES = {"none", "rotate", "float", "orbit"}
 HEX = re.compile(r"^#[0-9a-fA-F]{6}$")
@@ -141,6 +142,7 @@ class Obj(BaseModel):
     scale: List[float] = Field(default_factory=lambda: [1.0, 1.0, 1.0])
     color: str = "#88ccff"
     material: str = "standard"
+    preset: Optional[str] = None
     metalness: float = 0.3
     roughness: float = 0.4
     emissive: str = "#000000"
@@ -158,6 +160,14 @@ class Obj(BaseModel):
         v = str(v)
         return v if v in MATERIALS else "standard"
 
+    @field_validator("preset")
+    @classmethod
+    def _preset_field(cls, v: Any) -> Optional[str]:
+        if v is None:
+            return None
+        v = str(v).lower().strip()
+        return v if v in PRESET_NAMES else None
+
     @field_validator("position", "rotation", "scale")
     @classmethod
     def _vec3(cls, v: Any, info) -> List[float]:
@@ -364,6 +374,7 @@ class ExtrudeNode(BaseModel):
     bevel: bool = True
     color: str = "#88ccff"
     material: str = "standard"
+    preset: Optional[str] = None
     metalness: float = 0.3
     roughness: float = 0.4
     emissive: str = "#000000"
@@ -397,6 +408,14 @@ class ExtrudeNode(BaseModel):
         v = str(v)
         return v if v in MATERIALS else "standard"
 
+    @field_validator("preset")
+    @classmethod
+    def _preset_field(cls, v: Any) -> Optional[str]:
+        if v is None:
+            return None
+        v = str(v).lower().strip()
+        return v if v in PRESET_NAMES else None
+
     @field_validator("metalness", "roughness")
     @classmethod
     def _unit(cls, v: Any) -> float: