migrate to DirectX 9Ex from DirectX 9

src/GameLib/SnowEnvironment.cpp

@@ -257,14 +257,14 @@ bool CSnowEnvironment::__CreateGeometry()
 	if (FAILED(ms_lpd3dDevice->CreateVertexBuffer(sizeof(SParticleVertex) * m_dwParticleMaxNum * 4,
 		D3DUSAGE_DYNAMIC | D3DUSAGE_WRITEONLY,
 		D3DFVF_XYZ | D3DFVF_TEX1,
-		D3DPOOL_SYSTEMMEM,
+		D3DPOOL_DEFAULT,
 		&m_pVB, nullptr)))
 		return false;
 
 	if (FAILED(ms_lpd3dDevice->CreateIndexBuffer(sizeof(WORD) * m_dwParticleMaxNum * 6,
-		D3DUSAGE_WRITEONLY,
+		D3DUSAGE_DYNAMIC,
 		D3DFMT_INDEX16,
-		D3DPOOL_MANAGED,
+		D3DPOOL_DEFAULT,
 		&m_pIB, nullptr)))
 		return false;