Report: DirectDraw in Managed DirectX9

[CornedBee]

I took a look into Managed DirectX 9 with C#. I finally (after HOURS) managed to plot some lines via DirectDraw.

I'm not asking any questions here, I'm just reporting what I observed.

The documentation is non-existant. In order to know of what type collections that use the IEnumeration interface are you have to use:

if(en.MoveNext())
  Console.WriteLine(en.Current.GetType().FullNam);

because the docs don't mention of which type the objects actually are.
An example is the devices collection of DirectInput.

This also means that I had many guesses and many exceptions before I found out how to correctly initialize DirectDraw.

Then there is something I consider a bug in the Lock method. It returns a 2d byte array that represents the surface memory. This array has the same dimensions as the surface. This is nice if you are in 256-color mode. But in 16-, 24- or 32-bit modes where each pixel takes more than one byte this suddenly has the strange consequence that you can only access a part of the image!
There is a workaround because you can replace that pointer with one of your own.

The whole thing was awfully slow (with abot 5 fps) but that might have been my (very sloppily programmed) framework. I had to write it myself because the DX app wizard for C# doesn't work.

Tomorrow I'm going to profile my framework and see where it eats the speed. Probably in the allocation of the surface memory every frame...

Good job MS

[CornedBee]

Ok, I found out the speed hazard. It's the Lock call. It takes about 200-230 milliseconds when double-buffering and about 150-200 milliseconds when triple-buffering.

I have no idea why it's so slow.

[CornedBee]

Ok, so locking is obviously a bad idea in Managed DX9.

Blitting works nice and fast.

[PT Exorcist]

hmm whats the differences?

[CornedBee]

To what? DX in C++?


The creation of objects works differently. You don't have a DirectDraw or DirectInput or any other main object anymore. You directly create devices via their constructor. Same goes for all other objects, though you often have to pass the parent object (e.g. pass the device to the surface constructor).
Blt has been renamed to Draw, but that's about all.