directx questions

[Aaron Lovi]

Hi,

I'm a noob trying to use managed DirectX (VC# 2003, DX9.0 Apr 2005 SDK). I
used to use OpenGL with QT and VC++6.0, but I was a relative newcomer to
that as well.

When I used OpenGL, my understanding was that if you used display lists,
your vertices would normally be held in memory on the video card. Now, with
managed DirectX, I am looking at code that looks like this:

public void OnCreateVertexBuffer(object sender, EventArgs e)
{
VertexBuffer vb = (VertexBuffer)sender;
CustomVertex.PositionColored[] verts =
(CustomVertex.PositionColored[])vb.Lock(0,0);
verts[0].X=-1.0f; verts[0].Y=-1.0f; verts[0].Z=0.0f; verts[0].Color =
System.Drawing.Color.DarkGoldenrod.ToArgb();
verts[1].X=1.0f; verts[1].Y=-1.0f ;verts[1].Z=0.0f; verts[1].Color =
System.Drawing.Color.MediumOrchid.ToArgb();
verts[2].X=0.0f; verts[2].Y=1.0f; verts[2].Z = 0.0f; verts[2].Color =
System.Drawing.Color.Cornsilk.ToArgb();
vb.Unlock();
}

private void Render()
{
if (device == null)
return;
if (pause)
return;
//Clear the backbuffer to a blue color
device.Clear(ClearFlags.Target, System.Drawing.Color.Blue, 1.0f, 0);
//Begin the scene
device.BeginScene();
// Setup the world, view, and projection matrices
SetupMatrices();
device.SetStreamSource(0, vertexBuffer, 0);
device.VertexFormat = CustomVertex.PositionColored.Format;
device.DrawPrimitives(PrimitiveType.TriangleList, 0, 1);
//End the scene
device.EndScene();
device.Present();
}

Now, this code takes it's vertices from the Stream Source (the vertexBuffer)
which is in main CPU memory. I'm guessing these vertices have to cross the
bus to the video card, and then they are displayed. That sounds slower than
OpenGL display lists! Is there something in managed DirectX like an OpenGL
display list where the vertices are held in video card memory?

Thanks in advance,
Aaron Lovi
(e-mail address removed)

 

[Patrice]

I'm not sure what makes you think so. What matters is in which pool
(Pool.Default is the video memory) you created the vertex buffer...

If this is filling an array, see the Lock/Unlock pair as a download/upload
mechanism from/to video memory (if the vb was created there).

If this is because the "vertexBuffer is in main CPU memory", don't confuse
the "programming model" with the "real thing". The object that represents a
File is in system memory but it still *represents* or *symbolizes* something
that is actually stored on disk. The object itself is not the real thing -
we would need a philosopher here ;-)

For future questions, I strongly suggest :

microsoft.public.win32.programmer.directx.managed

Patrice