The bug was reproduced and the fix was verified by copying the following
code snippet into one of our Android samples:
val norm = floatArrayOf(1.0f, 0.0f, 0.0f)
val tang = floatArrayOf(0.0f, 1.0f, 0.0f, 1.0f)
val expected = floatArrayOf(0.5f, 0.5f, 0.5f, 0.5f)
val resultBuffer = FloatBuffer.allocate(4)
val qtc = VertexBuffer.QuatTangentContext()
qtc.quatCount = 1
qtc.quatType = VertexBuffer.QuatType.FLOAT4
qtc.outBuffer = resultBuffer
qtc.normals = FloatBuffer.wrap(norm)
qtc.tangents = FloatBuffer.wrap(tang)
VertexBuffer.populateTangentQuaternions(qtc)
Log.e("Filament", "${expected[0]} == ${resultBuffer[0]}")
Fixes#695.
691daeb45d