qgltf: Promote rgb to rgba for common material values

The spec uses FLOAT_VEC4 for colors. This means that while in the
custom material case we can use vec3 since we provide the type
information, the common materials path needs to promote all colors
to RGBA.

Change-Id: I1ac403807d0d6f0e9dfe14ea704c7f4a325495fa
Reviewed-by: Andy Nichols <andy.nichols@theqtcompany.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/tools/qgltf/qgltf.cpp b/tools/qgltf/qgltf.cpp
index 561e167b7..22ab5c84b 100644
--- a/tools/qgltf/qgltf.cpp
+++ b/tools/qgltf/qgltf.cpp
@@ -1750,6 +1750,23 @@ static inline QJsonArray vec2jsvec(const QVector<float> &v)
     return arr;
 }
 
+static inline void promoteColorsToRGBA(QJsonObject *obj)
+{
+    QJsonObject::iterator it = obj->begin(), itEnd = obj->end();
+    while (it != itEnd) {
+        QJsonArray arr = it.value().toArray();
+        if (arr.count() == 3) {
+            const QString key = it.key();
+            if (key == QStringLiteral("ambient")
+                    || key == QStringLiteral("diffuse")
+                    || key == QStringLiteral("specular"))
+                arr.append(1);
+                *it = arr;
+        }
+        ++it;
+    }
+}
+
 void GltfExporter::exportMaterials(QJsonObject &materials, QHash<QString, QString> *textureNameMap)
 {
     for (uint i = 0; i < m_importer->materialCount(); ++i) {
@@ -1847,6 +1864,9 @@ void GltfExporter::exportMaterials(QJsonObject &materials, QHash<QString, QStrin
                 QJsonObject commonMat;
                 commonMat["technique"] = prog->commonTechniqueName;
                 // Set the values as-is. "normalmap" is our own extension, not in the spec.
+                // However, RGB colors have to be promoted to RGBA since the spec uses
+                // vec4, and all types are pre-defined for common material values.
+                promoteColorsToRGBA(&vals);
                 commonMat["values"] = vals;
                 if (!opaque)
                     commonMat["transparent"] = true;