birt ean 128

birt gs1 128

birt ean 128

birt gs1 128

birt gs1 128

birt ean 128,
birt ean 128,
birt gs1 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt gs1 128,

birt gs1 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt ean 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt gs1 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt gs1 128,
birt gs1 128,
birt gs1 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt ean 128,
birt ean 128,
birt ean 128,
birt gs1 128,
birt gs1 128,
birt gs1 128,
birt gs1 128,

if __name__ == "__main__": run() Listing 8-8 starts out by creating a list of Vector3 objects with coordinates along the edges of a cube The points are then sorted by their z components, so that when they are rendered, the points nearer the viewer are drawn first Otherwise, distance points may overlap those that are close to the viewer and it will break the illusion of 3D Inside the main loop, the camera position is changed depending on which keys are currently pressed You can see that the code to move a 3D point is very similar to moving a 2D sprite, with only an additional z component that moves forward and back in the 3D scene The code to update the position with time-based movement is actually identical to the 2D calculation; it just used Vector3 objects rather than Vector2 objects.

Like variable types, the names of type parameters always start with a single quote (') followed by an alphanumeric name for the type. Typically, just a single letter is used. If multiple parameterized types are required, you separate them with commas. You can then use the type parameters throughout the type definition. The previous examples defined two parameterized types using the two different syntaxes that F# offers. The BinaryTree type used OCaml-style syntax, where the type parameters are placed

before the name of the type. The tree type used .NET-style syntax, with the type parameters in angle brackets after the type name. The syntax for creating and consuming an instance of a parameterized type does not change from that of creating and consuming a nonparameterized type. This is because the compiler will automatically infer the type parameters of the parameterized type. You can see this in the following construction of tree1 and tree2, and their consumption by the functions printBinaryTreeValues and printTreeValues: // definition of a binary tree type 'a BinaryTree = | BinaryNode of 'a BinaryTree * 'a BinaryTree | BinaryValue of 'a // create an instance of a binary tree let tree1 = BinaryNode( BinaryNode ( BinaryValue 1, BinaryValue 2), BinaryNode ( BinaryValue 3, BinaryValue 4) ) // definition of a tree type Tree<'a> = | Node of Tree<'a> list | Value of 'a // create an instance of a tree let tree2 = Node( [ Node( [Value "one"; Value "two"] ) ; Node( [Value "three"; Value "four"] ) ] ) // function to print the binary tree let rec printBinaryTreeValues x = match x with | BinaryNode (node1, node2) -> printBinaryTreeValues node1 printBinaryTreeValues node2 | BinaryValue x -> printf "%A, " x // function to print the tree let rec printTreeValues x = match x with | Node l -> List.iter printTreeValues l | Value x -> printf "%A, " x

Next in the code is a loop that draws all the points in the scene First, the point is adjusted so that it is relative to the camera by subtracting the camera_position variable If the resulting z component is greater than 0, it means that the point is in front of the camera and may be visible otherwise, there is no point in drawing it When the point is in front of the camera, it is projected by multiplying the x and y components by the viewing distance and dividing by the z component The y axis is also flipped to point in the right direction for the 2D drawing functions Finally the 2D coordinate is adjusted to place the world in the center of the screen by adding half the width (center_x) to the x component and half the height (center_y) to the y component.

Figure A-7. Creating the NorthwindWeb project After you click the OK button, Visual Studio will communicate with IIS to create the new website. When this process is complete, you should have a new Visual Studio project named NorthwindWeb displayed in the Solution Explorer, as shown in Figure A-8.

// print the results printBinaryTreeValues tree1 printfn "" printTreeValues tree2 The results of this example, when compiled and executed, are as follows: 1, 2, 3, 4, "one", "two", "three", "four", You may have noticed that although I ve discussed defining types, creating instances of them, and examining these instances, I haven t discussed updating them. It is not possible to update these kinds of types, because the idea of a value that changes over time goes against the idea of functional programming. However, F# does have some types that are updatable, and I discuss them in 4.

The remaining code draws a small diagram that shows how the viewing distance relates to the width of the screen and the fov It also displays a few pieces of information on screen so that you can see what effect the key presses have If you want to experiment with this demonstration, try adding other lists of points that create other objects, such as pyramids and spheres You might also want to make these objects move in 3D in the same way as we have done with 2D sprites in the preceding chapters..