d3dx9: Allow D3DX_DEFAULT to be passed as srclevel to D3DXFilterTexture.

dlls/d3dx9_36/tests/texture.c

@@ -758,6 +758,9 @@ static void test_D3DXFilterTexture(IDirect3DDevice9 *device)
 
     if (SUCCEEDED(hr))
     {
+        hr = D3DXFilterTexture((IDirect3DBaseTexture9*) tex, NULL, D3DX_DEFAULT, D3DX_FILTER_NONE);
+        ok(hr == D3D_OK, "D3DXFilterTexture returned %#x, expected %#x\n", hr, D3D_OK);
+
         hr = D3DXFilterTexture((IDirect3DBaseTexture9*) tex, NULL, 0, D3DX_FILTER_NONE);
         ok(hr == D3D_OK, "D3DXFilterTexture returned %#x, expected %#x\n", hr, D3D_OK);
 

dlls/d3dx9_36/texture.c

@@ -78,7 +78,9 @@ HRESULT WINAPI D3DXFilterTexture(IDirect3DBaseTexture9 *texture,
     if ((filter & 0xFFFF) > D3DX_FILTER_BOX && filter != D3DX_DEFAULT)
         return D3DERR_INVALIDCALL;
 
-    if (srclevel >= IDirect3DBaseTexture9_GetLevelCount(texture))
+    if (srclevel == D3DX_DEFAULT)
+        srclevel = 0;
+    else if (srclevel >= IDirect3DBaseTexture9_GetLevelCount(texture))
         return D3DERR_INVALIDCALL;
 
     switch (type = IDirect3DBaseTexture9_GetType(texture))