I skimmed bug #18490, and I'm wondering about two things: Does the app create
a D3DDEVTYPE_REF or D3DDEVTYPE_NULLREF device? Once the device is created,
what does it to with it? A +d3d log would provide some answers.
Ok, this needs a little correction on my part. The game actually
creates D3DEVTYPE_HAL (I somehow previously concluded it wouldn't work,
since on my test machine it required software vertex processing). Here is the relevant log line: trace:d3d:wined3d_device_create
wined3d 0x235ce558, adapter_idx 0, device_type 0x1, focus_window
0x20026, flags 0x22, device_parent 0x2284cc0c, device 0x2284cc14.
Focus
window is the desktop handle. Presentation parameters specify windowed
mode and hDeviceWindow=NULL, so in the end it uses the desktop window.
It seems to be some kind of short-lived auxiliary device for texture operations. It's not used for rendering at all. The only operations on that device I could find is a series of CreateTexture calls:
trace:d3d9:d3d9_device_CreateTexture
iface 0x2284cc08, width 2048, height 2048, levels 1, usage 0, format
0x15, pool 0x2, texture 0x33be40, shared_handle (nil).
They are followed by several LockRect/UnlockRect calls, after which the textures are released. The device is released immediately after that.
Originally
I suspected this might be used to generate mip-maps or load textures
with d3dx, but the presence of D3DPOOL_SYSTEMMEM excludes both.
I admit that it's a very non-standard way of creating a D3D device, since it can't render anything. However it seems to work for this particular use case.