what is the software processing?

is this problem is too simple?

When you create the d3d device in software processing mode, it means no T&L (transform and lighting) will be performed on the hardware. So vertex shaders will run on the CPU (i'm not 100% certain how this affects pixel shaders, i THINK you just can't use them in SW mode...someone correct me if i'm wrong). Fixed function pixel pipeline will still be performed on hardware (ie. rasterization).

So always create the device with hardware processing if possible (fall back to sw if its not possible).

SW processing can be useful if you want to run vertex shaders on a non shader compatible card, as it runs on the cpu fastish (software pixel shaders are horribly slow).

Quote:

Original post by cow_in_the_well (i'm not 100% certain how this affects pixel shaders, i THINK you just can't use them in SW mode...someone correct me if i'm wrong).

You're correct, you can't run pixel shaders on the CPU.

en,en,thank you
you mean if I declare SW.vertexprocessing,when I call drawprimitive,then the cpu will implement it,but the pixel processing will still on the gpu otherwise I also declare a SW. pixel rendering.
then I think ,if I use the cpu to draw,the program after the draw call would wait for the draw.on the other hand,if I draw vertex use gpu,the program those after draw call would not wait?

Quote:

Original post by firefire99 en,en,thank you you mean if I declare SW.vertexprocessing,when I call drawprimitive,then the cpu will implement it,but the pixel processing will still on the gpu otherwise I also declare a SW. pixel rendering. then I think ,if I use the cpu to draw,the program after the draw call would wait for the draw.on the other hand,if I draw vertex use gpu,the program those after draw call would not wait?

The program never waits for polygons to be drawn. Polygons are not usually drawn until you end your scene (in fact, in some cases they may not even be drawn then, some cards wait until a flip operation is initiated before drawing.)

Quote:

Original post by firefire99 then I think ,if I use the cpu to draw,the program after the draw call would wait for the draw.on the other hand,if I draw vertex use gpu,the program those after draw call would not wait?

I believe that software vertex processing tends to use a seperate thread, so no, it wouldn't wait for the draw call to finish. (If you've only got one CPU, then you'll find yourself sharing it with more stuff, but that's all handled transparently).