Attributes of output Primitive

Computer Graphics and Visualization

1. Attributes of Output Primitives

2. Main Areas… 2 Character Attributes Bundled Attributes Inquiry Functions Antialiasing

3. CHARACTER ATTRIBUTES

4. CHARACTER ATTRIBUTES The appearance of displayed characters is controlled by attributes such as Font size Color Orientation. Attributes can be set both for entire character strings (text) and for individual characters defined as marker symbols. 4

5. Text Attributes There are a great many text options that can be made available to graphics programmers. Typeface –choice of font, Set of character with a particular design i.e. courier, Helvetica, times roman etc. Assorted underlining styles Solid, dotted, double Boldface Italic Emboss Shadow style 5

6. A font and associated style is selected in a PHIGS program by setting an integer code for the text font parameter tf in the function setTextFont ( tf ) 6 Control of text color(intensity) is managed from an application program with setTextColourIndex ( tc )

7. Text size By scaling the overall dimensions of character Height Width Or scaling the height only Or scaling the width only 7 Text size can be adjusted without changing the width-to-height ratio of characters with setCharacterHeight ( ch )

8. Text size By scaling the overall dimensions of character Height Width Or scaling the height only Or scaling the width only 8 Height 1 Height 2 Height 3+

9. 9 The width of text can be set with the function setCharacterExpansionFactor ( cw ) where the character width parameter cw is set to a positive real value that scales the body width of characters. Spacing between characters is controlled separately with setCharacterSpacing ( cs ) where character spacing parameter cs can be asiigned any real value .

10. Orientation 10 ♦ Set according to the direction of a character up vector setCharacterUpVector ( upvect ) Parameter upvect is assigned two values that specify the x and y vector components.

11. Marker Attributes 11 A marker symbol is a single character that can be displayed in different colors and in different sizes. We select a particular character to be the marker symbol with setMarkertype ( mt ) where the marker type parameter mt is set to an integer code. we set the marker size with setMarkerSizeScalefactor ( ms ) ms is assigned a positive number.

12. 12 Marker color is specified with setPolymarkerColourIndex (mc) A selected color code for parameter mc is stored in the current attribute list and used to display subsequently specified marker primitives.

13. Bundled Attributes 13

14. BUNDLED ATTRIBUTES A particular set of attribute values tor a primitive on each output device is then chosen by specifying the appropriate table index. Attributes specified in this manner called bundled attributes 14

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16. Bundle Attributes Bundled Line Attributes Bundled Area-Fi Attributes Bundled Text Attributes Bundled Marker Attributes 16

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19. Inquiry Function 19

20. Antialiasing Increase resolution (increase sampling) Supersampling 20

21. Increase resolution (increase sampling) 21 Render the image at a higher resolution and downsample . Really, you are letting your eye do some filtering for you.

22. Supersampling For each pixel, we would like to figure out what “percentage” is covered. 22

23. THANK YOU!!!!!!! 23