addis&kimuli

8/3/2019 addis&kimuli

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By:ADDIS HAILU

KIMULI HAROLD


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` Interactive construction techniques means we willuse a technique to construct a picture.

` There are several techniques that areincorporated into graphics packages to aid theinteractive construction of pictures.

` Various input options can be provided, so thatcoordinate information entered with locator andstroke devices can be adjusted or interpreted

according to a selected option.` For example, we can restrict all lines to be either

horizontal or vertical.


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` Input coordinates can establish the position or

boundaries for ob~ to be drawn, or they can be used

to rearrange previously displayed objects.

`

There are different techniques this techniques:1. positioning

2. Dragging

3. Constraints

4. Grids:5. Circle Rubber Band Method

6. Gravity filed


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` Coordinate values supplied by locator input are oftenused with positioning methods to specify a location fordisplaying an object or a character string.

` We interactively select coordinate positions with a

pointing device, usually by positioning the screencursor. Just how the object or text-string positioning isperformed depends on the selected options.

` With a text string, for example, the screen pint couldbe taken as the centre string position, or the start orend position of the string,


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` For lines, straight line segments can be displayed

between two selected screen positions.

` As an aid in positioning objects, numeric values for

selected positions can be echoed on the screen.` Using the echoed coordinate values as a guide, we

can make adjustments in the selected location to

obtain accurate positioning.


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`Advantage :` We can easily change the location of an object with the

help of mouse` We can easily view where our object will appear on the

window.` We can easily observe one object can overlap with each

other or not.`

` Disadvantage`

` We can not get the actual position of an object.` We can not calculate accurate positioning point of an

objects.


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` It is a rule for altering input-coordinate values toproduce a specified orientation or alignment of thedisplayed coordinates.

` There are many kinds of constraint functions that can

be specified, but the most common constraint is ahorizontal or vertical alignment of straight lines.

` This type of constraint, is useful in forming networklayouts.

` With this constraint, we can create horizontal andvertical lines without worrying about precisespecification of endpoint coordinates.


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` A horizontal or vertical constraint is implemented by

determining whether any two input coordinate

endpoints are more nearly horizontal or more nearly

vertical.

` If the difference in the y values of the two endpoints

is smaller than the difference in x values, a horizontal

line is displayed. Otherwise, a vertical line is drawn.


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Advantage:

` We can modify a picture according to ourrequirement.

` We can perform various operation on picture

modification.` We can easily implement the rules over picture

construction and user can be bounded to do thetask.

Disadvantage` Some time one rule or constraint can not be

implemented on any application or object.


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` In this method we will divide a picture into grids.

` Grids will be constructed according to the size of animage. If image is large then grid will be moreotherwise grid will be less.

` Object will be arranged according to intersection ofrow and column . where intersection is happeningwhere object will be placed.

` Suppose one object location position at 4.6 then it isautomatically shifted to 5 if it is at 4.3 then it isautomatically shifted to 4.


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Advantage :

` Object will provide accurate position of an object

` Object can be moved from one grid location to

another location` Object are automatically shifted to rounded location

Disadvantage:

` We can not get accurate location of an object.

` We can not get accurate value of an object.

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