14

Pandora Aerobics 

14.0.0

Aerobics is part of the graphic program Pandora. This documentation about the Aerobics function is meant as an interesting study subject for all of you who are into making graphics & design or as being a programmer.

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14.0.1

Whenever you have questions about the explanation in this manual you should refer to the paragraph number which is listed at the left side column. This paragraph, which you are reading now for example, is numbered as paragraph 14.0.1

14.0.2

14.1

Pandora Aerobics

Introduction 

14.1.0

Introduction

'Aerobics' is based on an algorithm that usually is used to plot a circle with a variable precision. This base equation, executed with a certain amount of iterations to calculate a rotation of a point to plot, also allows to draw other shapes than circles. This is 'just' a matter of changing the parameters that normally are set to draw a circle. The algorithm is based on calculating the edge_points of a multiple_edged shape (a circle can be seen like this).

14.1.1

Manipulation

The Aerobics sub menu contains all the parameters to manipulate the algorithm in both its basics and extra effects. The possibilities of these effects has lead to an interesting and playable creation tool for images that can be seen as 'family' of the 'Miracle', 'Ambient' and 'Beam' creating tools.

The illustration above is a typical 'Aerobic' that can be found in many books on computer graphics. It is made by drawing sequentially a 'circle' that counts only 4 edges (thus a rectangular shape). After each cycle the rectangle was rotated a certain amount of degrees and at the same time the size was incremented.

14.1.2

Ready made

Not necessarily, the created images need to be so geometrically. The illustration below is an example of an Aerobic that is more extreme in its output. It is a piece made in one single session as a 'ready made' piece of Art. This means that the mouse is set at the center of the screen and then the left MouseKey is hit to draw the whole piece within a second. The LineStyle in this case was set as being the first 8 pixels set black and the second 8 set white.

14.2

Pandora Aerobics

Menu 

14.2.0

Aerobic menu

The Aerobics sub menu contents 12 presets to store Aerobics. They are created by setting the 9 parameters to a certain value and selecting the Alternating Flag's {A T F C Q}.

14.2.1

Parameters

Multi: Amount of edges of the 'circle'.
Xsize: Horizontal size (half diameter of the 'circle')
Ysize: Vertical size  (Half diameter of the 'circle')
Loop : Amount of repetition of the 'circle'
Xadd : Additive to Xsize after each 'loop'
Yadd : Additive to Ysize after each 'Loop'
Ratio: Deform factor of the circle_equation
Angle: Absolute start angle of the 'circle'
A_Add: Additive to Angle after each 'Loop'

14.2.2

Multi

When setting the amount of edges with the Multi parameter, you have to realize that the algorithm wants to create a 'circle'. The begin point and end point of a circle come together as being the same coordinate. This implies that the bending angle of the edges is a consequence of the equation: 360Edges. '360' as being the amount of degrees that represents the range of a circle and 'Edges' as being the Multi parameter. Thus, setting the Multi parameter to a value of 3 generates 3 edges that bend relative to each other 3603=120 degrees. This will lead to a rectangular shape.

14.2.3

Ratio

The Ratio parameter influences the rotation equation. When it is set negative, then the edges do not 'come circle_round' (less than 360 degrees). When the Ratio is set ]1, then the total bending of all edges exceed the 360 degrees ('overshoot').

14.2.4

Others

I presume that the other parameters became clear to you by studying the illustration in combination with the short parameter description. What remains are the Alternating flag's and the fact that the drawing executor uses the 'UDRAW' routine.
Read the item "BEAM", issue "UDRAW" to understand the drawing executor of this Aerobic item and the use of the flag's; {T}, {F}, and {C}. The {A} flag has its own specific Aerobic function and will be discussed in this item.

Some 'plane' Aerobics without any effects
!!! Graphic not yet included!

The illustration below is showing the effect of the negation of the A_add parameter. Hence that a positive value easily can be set negative by clicking the parameter title. For this illustration also the Multiply and Gmode parameter from the main graphical menu were set.

Notice that all settings of the Main graphical menu influence the way that an Areobic will finally work out. Also memorize the [K] and [H] functions to have the Aerobic created without the need to hold the mouse key manually pressed.

Set the mouse pointer somewhere and hit [K] or set the Hold mode by pressing [H] and only hit shortly = free wheeling until pressed again.

14.2.5

Negation A_add

14.2.6

Alternate {A}

The illustration above demonstrates the effect of the Alternate flag {A}. All parameters of the Aerobic sub menu are listed in the illustration. Notice that the Multiply and Gmode were set to generate a specific texture to accentuate the effect of the images that have the {A} flag set and also to demonstrate the effect of the absolute angle setting under certain circumstances.

by Marc Marc (C)1991...2001