Fix OOB Writing issue when using sparse accessors (#78)

* Fix OOB issue

* Moved check to outer loop

Author: PolygonalSun

GLTFSDK/Inc/GLTFSDK/GLTFResourceReader.h

@@ -389,9 +389,13 @@ namespace Microsoft
 
                 for (size_t i = 0; i < indices.size(); i++)
                 {
-                    for (size_t j = 0; j < typeCount; j++)
+                    // Verify provided index is valid before storing value
+                    if ((indices[i] * typeCount + (typeCount - 1)) < baseData.size())
                     {
-                        baseData[indices[i] * typeCount + j] = values[i * typeCount + j];
+                        for (size_t j = 0; j < typeCount; j++)
+                        {
+                            baseData[indices[i] * typeCount + j] = values[i * typeCount + j];
+                        }
                     }
                 }
             }