diff --git a/src/materials/MatcapMaterial.js b/src/materials/MatcapMaterial.js
index 5d5c384..6595aed 100644
--- a/src/materials/MatcapMaterial.js
+++ b/src/materials/MatcapMaterial.js
@@ -8,6 +8,7 @@ export default {
   props: {
     src: String,
     name: String,
+    flatShading: Boolean,
   },
   methods: {
     createMaterial() {
@@ -16,6 +17,9 @@ export default {
       opts.matcap = new TextureLoader().load(src);
       this.material = new MeshMatcapMaterial(opts);
     },
+    addWatchers() {
+      // TODO
+    },
   },
   __hmrId: 'MatcapMaterial',
 };
diff --git a/src/materials/Material.js b/src/materials/Material.js
index 1ded368..f36d43d 100644
--- a/src/materials/Material.js
+++ b/src/materials/Material.js
@@ -7,7 +7,6 @@ export default {
     color: { type: [String, Number], default: '#ffffff' },
     depthTest: { type: Boolean, default: true },
     depthWrite: { type: Boolean, default: true },
-    flatShading: Boolean,
     fog: { type: Boolean, default: true },
     opacity: { type: Number, default: 1 },
     side: { type: Number, default: FrontSide },
@@ -38,7 +37,6 @@ export default {
       this.setProp(key, texture, true);
     },
     _addWatchers() {
-      // don't work for flatShading
       ['color', 'depthTest', 'depthWrite', 'fog', 'opacity', 'side', 'transparent'].forEach(p => {
         watch(() => this[p], () => {
           if (p === 'color') {
diff --git a/src/materials/PhongMaterial.js b/src/materials/PhongMaterial.js
index e7c4a1a..77a7c43 100644
--- a/src/materials/PhongMaterial.js
+++ b/src/materials/PhongMaterial.js
@@ -11,12 +11,14 @@ export default {
     reflectivity: { type: Number, default: 1 },
     shininess: { type: Number, default: 30 },
     specular: { type: [String, Number], default: 0x111111 },
+    flatShading: Boolean,
   },
   methods: {
     createMaterial() {
       this.material = new MeshPhongMaterial(propsValues(this.$props));
     },
     addWatchers() {
+      // TODO : handle flatShading ?
       ['emissive', 'emissiveIntensity', 'reflectivity', 'shininess', 'specular'].forEach(p => {
         watch(() => this[p], (value) => {
           if (p === 'emissive' || p === 'specular') {
diff --git a/src/materials/PhysicalMaterial.js b/src/materials/PhysicalMaterial.js
index 95ba19e..d8dca76 100644
--- a/src/materials/PhysicalMaterial.js
+++ b/src/materials/PhysicalMaterial.js
@@ -4,10 +4,16 @@ import StandardMaterial from './StandardMaterial';
 
 export default {
   extends: StandardMaterial,
+  props: {
+    flatShading: Boolean,
+  },
   methods: {
     createMaterial() {
       this.material = new MeshPhysicalMaterial(propsValues(this.$props));
     },
+    addWatchers() {
+      // TODO
+    },
   },
   __hmrId: 'PhysicalMaterial',
 };
diff --git a/src/materials/StandardMaterial.js b/src/materials/StandardMaterial.js
index 562a1da..062f6b1 100644
--- a/src/materials/StandardMaterial.js
+++ b/src/materials/StandardMaterial.js
@@ -16,6 +16,7 @@ const props = {
   normalScale: { type: Object, default: { x: 1, y: 1 } },
   roughness: { type: Number, default: 1 },
   refractionRatio: { type: Number, default: 0.98 },
+  flatShading: Boolean,
   wireframe: Boolean,
 };
 
@@ -27,7 +28,7 @@ export default {
       this.material = new MeshStandardMaterial(propsValues(this.$props, ['normalScale']));
     },
     addWatchers() {
-      // todo : use setProp ?
+      // TODO : use setProp, handle flatShading ?
       Object.keys(props).forEach(p => {
         if (p === 'normalScale') return;
         watch(() => this[p], (value) => {