Transcript 3D Graphics in WPF

Rujchai Ung-arunyawee
Department of Computer Engineering
Khon Kaen University
3D Graphics Basics: The Scene
 A three dimensional model of an object
 A camera that takes a picture of the object
 A viewport (projection surface) for a picture , which
is a projection of the object to a planar surface
 The 3D rendering engine determines the color for
every pixel by calculating the amount of light that is
reflected by any light sources
 All surfaces of objects have a material (brush). The
material defines how much light is reflected for a
specific angle and the brush defines the color.
 A brush can either be a simple color or a gradient or
even an image called texture
3D WPF is a world of triangles
 A surface of a 3D object is called a mesh
 A mesh is defined by a number of 3D points called
Vertices (Vertex)
 The vertices are joined together by a winding pattern
to define the triangles
 Every triangle has a front and a back side. Only the
front side is rendered
 WPF uses a counter clockwise winding pattern
WPF is a right handed coordinate
system
WPF Elements of a 3D scene
 Viewport3D
 The viewport is the control that builds the gate between the
2D and the 3D world.
 Camera
 Every 3D scene has excactly one camera. The camera defines
the Position and the LookDirection and the UpDirection of
the viewer. WPF supports orthographical and perspective
cameras.
 3D Models
 A 3D model defines an object in the scene. It has a Geometry
that is the mesh and a Material that can be a diffuse, specular
or emmisive material. The material itself has a brush.
 Lights
 Without any lights you see nothing. So we need to place at
least one light in our scene to illuminate our models
A Point in Space
 In C# code, we create and initialize a Point3D
object:
 In XAML, you represent a Point3D objects as a text
string with spaces and/or single commas
separating the numbers:
or
Points in Space
 In C# code, use the Point3DCollection class
 In XAML, just by listing them in a string:
Vectors
 A vector encapsulates a magnitude and a direction
Points and Vectors Relationship
 For vector (xv, yv, zv), the direction of the vector is
the direction from the origin (0, 0, 0) to the point
(xv, yv, zv).
 The magnitude of the vector (M) is
 The normalized vectors or unit vectors will have
magnitude of 1
 point ± point  vector
 point ± vector  point
 vector * D  vector
 vector / D  vector
Define the 3D object
Define the simplest light
 A 3D scene usually requires some light.
 If you don't have any light in a 3D scene, you'll still
be able to see the figures you've created, but they
won't have any color
 Different types of light are available in WPF 3D
 The simplest light is a class named AmbientLight
which has a white color by default.
or
Define the simplest camera
 The camera must be located in a specific position
in 3D space by setting the Position property
 You also need to specify a direction in which the
camera is pointed by setting the LookDirection
property.
 The simplest camera
 Sits right on the positive Z axis, which means that
the X and Y coordinates are set to zero
 Points in a direction parallel to the negative Z axis,
which is the vector (0, 0, –1)
<PerspectiveCamera Position=“0 0 5"
LookDirection="0 0 –1" />
Camera In the scene
The Viewport3D and Its Constituents
 We generally define a whole 3D scene inside a
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Viewport3D element
It can be a part of a larger layout of elements, and
it can receive mouse, keyboard, and stylus input
Viewport3D defines a ModelVisual3D and Camera
properties.
ModelVisual3D has a property named Content
Each Content might contains GeometryModel3D
or Light
GeometryModel3D has a Geometry, Material, and
BackMaterial properties.
Ggeneral structure of a simple
Viewport3D
Put everything together
Model3DGroup
 Combine the geometry and light into one
Light sources
 AmbientLight
 Setting a Color property
 DirectionalLight
 Setting Color and Direction properties.
 PointLight
 SpotLight
DirectionalLight
PointLight
SpotLight
Camera
 Perspective Camera
 Orthographic Camera
PerspectiveCamera
OrthographicCamera
LookDirection property
 A vector that points from the Position property to the
target point (x, y, z).
 If the Position property is (–2, 0, 5) and the target is
the origin (0, 0, 0), the calculation is
(0, 0, 0) – (–2, 0, 5) = (2, 0, –5)
 It's also possible to calculate LookDirection so that the
center of the triangle appears in the center of the
display
(0, 0.5, –1) – (–2, 0, 5) = (2, 0.5, –6)
Field Of View (FOV)