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Code Elements and Processing Coordinate System

Code Elements and Processing Coordinate System. Code elements: pages 17-21. Comments: are documentation notes that are ignored by the computer but are important for people (to understand the code). // single line comment /* multi line comment */ Semi-colon (“;” ) is a terminator

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Code Elements and Processing Coordinate System

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  1. Code Elements and Processing Coordinate System

  2. Code elements: pages 17-21 • Comments: are documentation notes that are ignored by the computer but are important for people (to understand the code). // single line comment /* multi line comment */ Semi-colon (“;” ) is a terminator Example: size (600, 600);

  3. Functions • Functions are pre-defined operations • You can define the functions or use the functions already defined and available in libraries/packages • Functions promote modular design • Example: size(500,500); background(102); parameters Function call

  4. Expressions • Expression are means for expressing a computation or logic • Example: • 56 + 100 value is 156 • 89 > 90 value is false

  5. Variables and types • Variables represent items in the problem to be solved • Variables have (i) type (ii) name by which they are referenced in the code • Example: int age; float wage; char initial; We will discuss variables in more detail later.

  6. Console and Printing Messages • Processing has two instructions for printing out on console: print(…) and println(..) • These can be used to display data when a Processing code is running • Good instructions for understanding your code and trace what is happening with the code. Good “debugging” tool. • Example: (see p.21) int x = 20; println(x); int x2 = 20; int y2 = 30; println(x2 + “ “ + y2); println(“I am learning Problem solving using Processing”);

  7. Coordinates and Primitives • Before you “draw” you need to think about dimensions and qualities of the surface on which you’ll be drawing. • Computer monitor have surfaces that are defined by “pixels” or a “picture element” • When the definition of the screen of your laptop is 1280 X 1024 that means you have 1,310,720 little pixels to display your content on the screen • In processing when you say “size (200, 100)” we have width of 200 pixels and height of 100 pixels

  8. Processing Coordinate System (10X10) X  0,0 Y  10,10

  9. Primitive Shapes • point(x,y) • Example: point(2, 67); • line(x1,y1, x2, y2) • Example: line(23,45, 56,90); • triangle(x1,y1,x2,y2,x3,y3); • Example: triangle(60,10,25,60,75,65);

  10. More Primitive Shapes • quad(20,20,20,70,60,90,60,40); • quad(20,20,70,-20,110,0,60,40); • Quad is specified using points • Rect function uses starting point and lengths • rect(x, y, width, height); • ellispe(x,y,width,height); // is used for drawing circle

  11. Complete example • Lets draw a desktop computer. rect(0, 0, 90, 50); rect(5, 50, 75,4); rect(24, 54, 6,6); rect(64,54, 6, 6); rect(20, 60, 75, 10); rect(10, 70, 80, 2);

  12. Drawing attributes • fill(r,g,b); • Before you draw will fill the object you draw with the fill color. • smooth(); noSmooth(); • strokeWidth(6); • noStroke(); • Lets try these commands on Processing

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