Clamp FBX values to glTF specifications (#80)

There seem to be few constraints on what values FBX properties can take. By contrast, glTF constrains e.g. common material factors to lie in [0, 1]. We take a simple approach and just clamp.

src/glTF/MaterialData.cpp

@@ -36,14 +36,24 @@ void to_json(json &j, const KHRCmnUnlitMaterial &d)
 	j = json({});
 }
 
+inline float clamp(float d, float bottom = 0, float top = 1) {
+    return std::max(bottom, std::min(top, d));
+}
+inline Vec3f clamp(const Vec3f &vec, const Vec3f &bottom = VEC3F_ZERO, const Vec3f &top = VEC3F_ONE) {
+    return Vec3f::Max(bottom, Vec3f::Min(top, vec));
+}
+inline Vec4f clamp(const Vec4f &vec, const Vec4f &bottom = VEC4F_ZERO, const Vec4f &top = VEC4F_ONE) {
+    return Vec4f::Max(bottom, Vec4f::Min(top, vec));
+}
+
 PBRMetallicRoughness::PBRMetallicRoughness(
     const TextureData *baseColorTexture, const TextureData *metRoughTexture,
     const Vec4f &baseColorFactor, float metallic, float roughness)
     : baseColorTexture(Tex::ref(baseColorTexture)),
       metRoughTexture(Tex::ref(metRoughTexture)),
-      baseColorFactor(baseColorFactor),
+      baseColorFactor(clamp(baseColorFactor)),
-      metallic(metallic),
+      metallic(clamp(metallic)),
-      roughness(roughness)
+      roughness(clamp(roughness))
 {
 }
 
@@ -78,7 +88,7 @@ MaterialData::MaterialData(
       isTransparent(isTransparent),
       normalTexture(Tex::ref(normalTexture)),
       emissiveTexture(Tex::ref(emissiveTexture)),
-      emissiveFactor(emissiveFactor),
+      emissiveFactor(clamp(emissiveFactor)),
       khrCmnConstantMaterial(khrCmnConstantMaterial),
       pbrMetallicRoughness(pbrMetallicRoughness) {}
 

src/mathfu.h

@@ -58,6 +58,11 @@ typedef mathfu::Matrix<float, 4>    Mat4f;
 typedef mathfu::Quaternion<float>   Quatf;
 typedef Bounds<float, 3>            Boundsf;
 
+const Vec3f VEC3F_ONE  = Vec3f {1.0f};
+const Vec3f VEC3F_ZERO = Vec3f {0.0f};
+const Vec4f VEC4F_ONE  = Vec4f {1.0f};
+const Vec4f VEC4F_ZERO = Vec4f {0.0f};
+
 template<class T, int d> static inline std::vector<T> toStdVec(const mathfu::Vector <T, d> &vec)
 {
     std::vector<T> result(d);