ptex: Store full metadata only at subimage 0, miplevel 0 for ptex fil…

…es. (AcademySoftwareFoundation#4376)

Don't read or store full metadata on every MIP level for every face.
That can really add up! Ptex can only have one set of metadata, the
format itself doesn't allow it to vary from face to face.

Signed-off-by: Larry Gritz <lg@larrygritz.com>

src/ptex.imageio/ptexinput.cpp

@@ -66,6 +66,8 @@ class PtexInput final : public ImageInput {
         m_subimage = -1;
         m_miplevel = -1;
     }
+
+    void get_ptex_metadata(PtexMetaData* pmeta);
 };
 
 
@@ -190,6 +192,29 @@ PtexInput::seek_subimage(int subimage, int miplevel)
         wrapmode += "periodic";
     m_spec.attribute("wrapmode", wrapmode);
 
+    // Add the arbitrary metadata. For Ptex, we only add full metadata to the
+    // first MIP level of the first subimage. The PTex format doesn't permit
+    // metadata to differ per-face anyway.
+    if (subimage == 0 && miplevel == 0) {
+        if (PtexMetaData* pmeta = m_ptex->getMetaData()) {
+            get_ptex_metadata(pmeta);
+            pmeta->release();
+        }
+    }
+
+    facedata->release();
+    return true;
+}
+
+
+
+void
+PtexInput::get_ptex_metadata(PtexMetaData* pmeta)
+{
+    if (!pmeta)
+        return;
+
+        // Helper macro to get metadata of a specific type
 #define GETMETA(pmeta, key, ptype, basetype, typedesc, value) \
     {                                                         \
         const ptype* v;                                       \
@@ -199,47 +224,40 @@ PtexInput::seek_subimage(int subimage, int miplevel)
         value    = (const void*)v;                            \
     }
 
-    PtexMetaData* pmeta = m_ptex->getMetaData();
-    if (pmeta) {
-        int n = pmeta->numKeys();
-        for (int i = 0; i < n; ++i) {
-            const char* key = NULL;
-            Ptex::MetaDataType ptype;
-            pmeta->getKey(i, key, ptype);
-            OIIO_DASSERT(key);
-            const char* vchar;
-            const void* value;
-            TypeDesc typedesc;
-            switch (ptype) {
-            case Ptex::mdt_string:
-                pmeta->getValue(key, vchar);
-                value    = &vchar;
-                typedesc = TypeDesc::STRING;
-                break;
-            case Ptex::mdt_int8:
-                GETMETA(pmeta, key, int8_t, TypeDesc::INT8, typedesc, value);
-                break;
-            case Ptex::mdt_int16:
-                GETMETA(pmeta, key, int16_t, TypeDesc::INT16, typedesc, value);
-                break;
-            case Ptex::mdt_int32:
-                GETMETA(pmeta, key, int32_t, TypeDesc::INT32, typedesc, value);
-                break;
-            case Ptex::mdt_float:
-                GETMETA(pmeta, key, float, TypeDesc::FLOAT, typedesc, value);
-                break;
-            case Ptex::mdt_double:
-                GETMETA(pmeta, key, double, TypeDesc::DOUBLE, typedesc, value);
-                break;
-            default: continue;
-            }
-            m_spec.attribute(key, typedesc, value);
+    int n = pmeta->numKeys();
+    for (int i = 0; i < n; ++i) {
+        const char* key = NULL;
+        Ptex::MetaDataType ptype;
+        pmeta->getKey(i, key, ptype);
+        OIIO_DASSERT(key);
+        const char* vchar;
+        const void* value;
+        TypeDesc typedesc;
+        switch (ptype) {
+        case Ptex::mdt_string:
+            pmeta->getValue(key, vchar);
+            value    = &vchar;
+            typedesc = TypeDesc::STRING;
+            break;
+        case Ptex::mdt_int8:
+            GETMETA(pmeta, key, int8_t, TypeDesc::INT8, typedesc, value);
+            break;
+        case Ptex::mdt_int16:
+            GETMETA(pmeta, key, int16_t, TypeDesc::INT16, typedesc, value);
+            break;
+        case Ptex::mdt_int32:
+            GETMETA(pmeta, key, int32_t, TypeDesc::INT32, typedesc, value);
+            break;
+        case Ptex::mdt_float:
+            GETMETA(pmeta, key, float, TypeDesc::FLOAT, typedesc, value);
+            break;
+        case Ptex::mdt_double:
+            GETMETA(pmeta, key, double, TypeDesc::DOUBLE, typedesc, value);
+            break;
+        default: continue;
         }
-        pmeta->release();
+        m_spec.attribute(key, typedesc, value);
     }
-
-    facedata->release();
-    return true;
 }