From 362b8bd7618b4b862a39524a093b9268b42abae9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A4r=20Winzell?= <par.winzell@alyx.com>
Date: Sun, 25 Feb 2018 18:13:19 -0800
Subject: [PATCH] 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 | 18 ++++++++++++++----
 src/mathfu.h              |  5 +++++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/glTF/MaterialData.cpp b/src/glTF/MaterialData.cpp
index c8a8d5f..0360c33 100644
--- a/src/glTF/MaterialData.cpp
+++ b/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),
-      metallic(metallic),
-      roughness(roughness)
+      baseColorFactor(clamp(baseColorFactor)),
+      metallic(clamp(metallic)),
+      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) {}
 
diff --git a/src/mathfu.h b/src/mathfu.h
index 922267f..11cca93 100644
--- a/src/mathfu.h
+++ b/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);