Lesson 2: Homework Answers

1)  Colour is stored as 0xRRGGBBAA, so if I increment the second hex digit, I get a little more reddy colour.

2)  GIFtag as before
    RGBAQ: 0xFF000000
    XYZ2: (2048 - 320, 2048 - 112, 1)
    RGBAQ: 0x00FF0000
    XYZ2: (2048 + 320, 2048 - 112, 1)
    RGBAQ: 0x0000FF00
    XYZ2: (2048 + 320, 2048 + 112, 1)
    
    
3)  GIFtag (NLOOP = 6, NREG stays at 2)
    RGBAQ: 0xFF000000
    XYZ2: (2048 - 320, 2048 - 112, 1)
    RGBAQ: 0x00FF0000
    XYZ2: (2048 + 320, 2048 - 112, 1)
    RGBAQ: 0x0000FF00
    XYZ2: (2048 + 320, 2048 + 112, 1)
    RGBAQ: 0xFF000000
    XYZ2: (2048 - 320, 2048 - 112, 1)
    RGBAQ: 0x00FF0000
    XYZ2: (2048 - 320, 2048 + 112, 1)
    RGBAQ: 0x0000FF00
    XYZ2: (2048 + 320, 2048 + 112, 1)
    
I said anywhere in the bottom-left, this would actually cover the bottom left.  Fill it in with flat-shading, and you've got yourself an easy way to clear the screen with the colour of your choice...    

4)  PRIM : (PRIM = 0 (points), IIP = 0, TME = 0, FGE = 0, ABE = 0, AA1 = 0, CTXT = 0, FIX = 0)
    GIFtag (NLOOP = 1, NREG = 2, EOP = 1, PRE = 1, PRIM as above, FLG = 0 (PACKED), REGS = 0x51)
    RGBAQ: 0x0000FF00
    XYZ2: (2048 - 50, 2048 + 50, 1)
    
5)  Take the above GIFtag with NLOOP changed to 5, then add
    RGBAQ: 0x00FF0000
    XYZ2: (2048 - 50, 2048 + 50, 1)
    RGBAQ: 0x00FF0000
    XYZ2: (2048 - 40, 2048 + 50, 1)
    RGBAQ: 0x00FF0000
    XYZ2: (2048 - 30, 2048 + 50, 1)
    RGBAQ: 0x00FF0000
    XYZ2: (2048 - 20, 2048 + 50, 1)
    RGBAQ: 0x00FF0000
    XYZ2: (2048 - 10, 2048 + 50, 1)

This was just practice in filling out the fields of the GIFtag.  Next lessons homework answers will convert this into actual, useable code.