First Steps with Managed DirectX

What is Managed DirectX?

DirectX: Microsoft's API for fast graphics (DirectX Graphics, formerly Direct3D and DirectDraw), audio processing (DirectSound), networked gaming (DirectPlay), etc., written in C.
Managed DirectX: Object-oriented wrapper for DirectX in .NET
Allows DirectX to be used with C#, Visual Basic .NET, C++ with Managed Extensions, Delphi .NET, etc.

Basic drawing using Managed DirectX

Include references to the following DLLs: Microsoft.DirectX, Microsoft.DirectX.Direct3D, Microsoft.DirectX.Direct3DX

// class members
private Device device;
private VertexBuffer vertices;

// Initialization, for instance in the constructor of the Form object
SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint | ControlStyles.Opaque, true);
PresentParameters presentParams = new PresentParameters();
presentParams.Windowed = true;
presentParams.SwapEffect = SwapEffect.Discard;
presentParams.AutoDepthStencilFormat = DepthFormat.D24X8;
presentParams.EnableAutoDepthStencil = true;
device = new Device(0, DeviceType.Hardware, this, CreateFlags.HardwareVertexProcessing, presentParams);
vertices = new VertexBuffer(typeof(CustomVertex.PositionColored), 3, device, Usage.WriteOnly, 0, Pool.Managed);
CustomVertex.PositionColored[] v = (CustomVertex.PositionColored[])vertices.Lock(0, LockFlags.None);
v[0] = new CustomVertex.PositionColored(0.6f, 0.1f, 0.0f, Color.Green.ToArgb());
v[1] = new CustomVertex.PositionColored(-0.9f, 0.8f, 0.0f, Color.Red.ToArgb());
v[2] = new CustomVertex.PositionColored(0.2f, -0.6f, 0.0f, Color.Yellow.ToArgb());
vertices.Unlock();

// Drawing, typically in the OnPaint function of the Form object
device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.Blue, 1.0f, 0);
device.BeginScene();
device.SetStreamSource(0, vertices, 0);
device.VertexFormat = CustomVertex.PositionColored.Format;
device.RenderState.Lighting = false;
device.RenderState.CullMode = Cull.None;
device.DrawPrimitives(PrimitiveType.TriangleList, 0, 1);
device.EndScene();
device.Present();

Debugging DirectX programs

After the DirectX SDK is installed, DirectX can be set to the (fast) retail version or the (slower) debug version using its control panel. The debug version sends warnings and error messages to a debug monitor, for instance the output window of Visual Studio. Be sure to enable "Unmanaged Debugging" in the properties of the project.
PIX, a utility contained in the DirectX SDK, allows to capture all DirectX commands in real time and to display statistics to aid in optimization.

Projection, Linear Perspective

So now we can draw triangles using DirectX. But how does the z coordinate work?

Sensing depth (and how to simulate depth)

Overlapping (i.e. hidden surfaces)
Foreshortening [perspektivische Verkürzung]
Shadows [Schatten]
Shading [Schattierung]
Stereoscopic viewing: disparity, vergence
Aerial perspective [Luftperspektive] = Haze [Dunst]
Depth of field [Tiefenschärfe, Schärfentiefe]
Accomodation (tension of eye lens)
Motion parallax (changes due to moving viewer)
Object motion
etc.

Projections: How to turn 3D space into 2D images

Linear projections: lines in 3D are converted to lines (or segments of lines) in 2D

Parallel projections: parallel lines in 3D are converted to parallel lines in 2D

Orthogonal projection (in technical drawing this means: orthogonal projection along a principal direction): project perpendicular to the image plane, e.g., as in the "Front", "Top", and "Left" views in standard 3D software
Isometric projection: The units on the x, y, and z axes have the same length.
etc.

Linear perspective: Project using rays converging in a common vantage point. Consequences: foreshortening; vanishing points [Fluchtpunkte] for parallel lines that are not parallel to the image plane. Construction. Demo: field of view

Non-linear projections