Realtime raytraced shadows: mission impossible?

I don't know, I only know I would love to have access to the depth buffer :)
I really should learn this DX7 stuff, this might be useful. The only DLL by Tom I know it the memory lib:
-peeking and poking absolute adresses
-get camera properties
-get texture properties
-get entity properties
-get buffer properties
-get brush properties

although there is one function "LockedDepth%(buffer%)", I doubt this gives access to the depth buffer since it takes only one parameter and not x and y.

So DX7.dl is something diffrent? I'll try to locate it.

EDIT

Paolo: here it is: http://www.tomspeed.com/shadowvolume/

Well thank you Tom.

THe decls file says:

.lib "dx7test.dll"

GetRenderTarget%(d3dDevice):"_GetRenderTarget@4"
;SetRenderTarget%(d3dDevice,buffer):"_SetRenderTarget@8"



SupportsWBuffer%(d3dDevice):"_SupportsWBuffer@4"
MaxTextureWidth%(d3dDevice):"_MaxTextureWidth@4"
MaxTextureHeight%(d3dDevice):"_MaxTextureHeight@4"
ZBufferBitDepth%(d3dDevice):"_ZBufferBitDepth@4"

SetRenderState%(d3dDevice%,renderstate%,param%):"_SetRenderState@12"
DeviceClear%(d3dDevice, dwFlags%, dwColorRGBA%, dvZ#, dwStencil%):"_DeviceClear@20"
DeviceClear2%(d3dDevice, BBRect*,dwFlags%, dwColorRGBA%, dvZ#, dwStencil%):"_DeviceClear2@24"


It seems this was used for the stencil shadows demo. Not sure if it let's you access the depth buffer. ZBufferBitDepth - what ever that means. You know, it would be cool if we could do something like "SetBuffer ZBuffer()" and then simly ReadPixelFast the depth.