3. NAPA Online Manuals 2009

Surfaces can be classified into two groups under NAPA: A surface can either be a general surface, in which case thesurface is defined by a set of curves (grid) or it can be a special surface, for example, a plane, a cylinder, a sphere,etc. Hull surfaces are typically general surfaces, and most of the surfaces needed in the internal geometry arespecial surfaces. We will concentrate on the theory of surface definition. In this chapter we will continue to definethe patrol boat hull using the Geometry Window. General properties of the Geometry Window tool will also bediscussed. In the following chapter we will create a couple of simple fore and aft bodies in order to give some ideasfor sample grids for different types of hull forms.

6.1 General surfaces

The syntax of a general surface is:

SUR name 'descr. text'

THR curve1, curve2, curve3, ...

[OUT x, y or z]

If the outside of the surface is not defined, NAPA uses OUT Y as a default which, at least regarding normalhulls, is nearly always the right selection. The information about the orientation of the surface is requiredwhen defining rooms.

Let us have an example. We have created a surface named CSUR - as illustrated in the next figure - consistingof five curves, C1 ... C5. We can check the definition with the command DES *CSUR, in which the *-symbolmeans 'show also the curves the surface is referring to'. The command gives us the following printout,showing us how the surface was defined.

CUR C1; Z, 0

XY (70, 110), (100, 130), (140, 140)

CUR C2; Z, 10

XY (70, 175), (100, 195), (140, 205)

CUR C3; X, 70

YZ C1, C2

CUR C4; X, 100

YZ C1, C2

CUR C5; X, 140

YZ C1, C2

SUR, CSUR, P

THR C1, C2, C3, C4, C5

OUT, Z

It is recommended that all intersections between curves are explicit, i.e. one curve references the other.Otherwise, the intersection points have to be found geometrically, and this may fail in some cases. Forexample, the following definition would not necessarily work because there are no explicitly definedintersection points between curve C1, C2 and C3.

CUR C1; Z, 0

XY (70, 110), (100, 130), (140, 140)

6 Surfaces file:///C:/Napa/man/Man091/html/intro/surfaces/index.html

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CUR C2; Z, 10

XY (70, 175), (100, 195), (140, 205)

CUR C3; X, 70

YZ (110, 0), (175, 10)

etc.

To NAPA they just seem to have the same coordinates at their end points, and without a direct reference toeach other, NAPA interprets the situation in just this way. The same applies to point objects. Two or morecurves can have a point object as their definition point, but to NAPA there is no intersection point betweenthem unless the second curve refers to the first curveby means of the syntax CURVE1/POINT.

The previous example had a surface with two PATCHES. A patch is the finite element of a surface, and thesurface is just a collection of patches. A patch is an area which is limited by the nearest curves in the GRID. Agrid is a collection of curves used in general surface definition.

The patches always have four sides. If the surface element has more than four sides, it has to be divided aspresented by the figure below. This is done automatically at preparation, but for high quality fairing it is notrecommended to rely on this automatic function, as the division may not be the best one.

A patch is mathematically described by the coordinates of its corner points and by the angles from eachcorner point along the sides and across the surface. In total 48 parameters are needed to describe eachpatch. The parameters are:

corner points (x, y, z) 3 x 4= 12

corner derivates (dx, dy, dz) 2 x 3 x 4 = 24

cross derivates (dx, dy, dz) 3 x 4 = 12

In the case of triangles, there are two alternatives for defining a surface. As a default, the patch is consideredto have four corner points, two of which coincide. The patch can optionally be defined with a virtual cornerpoint outside the patch area. The patch can then be considered as a four-sided patch with a restricted area.The genuine three-sided patch gives, in general, a better fairness in relatively flat areas, while the defaultmethod is recommended for highly-curved places.


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After the grid has been defined, it is time to check the results. Three very important commands for this, willbe explained here. Note that the same functions as performed by these commands can be achieved using theGeometry Window.

UPD {surface} updates all grid references. For example, if curve C2 referring to C1 and C1 had recentlybeen changed, curve C2 would be updated with the command UPD C2 or UPD CSUR.

PRE {surface} prepares the surface for a patch representation. Practically speaking, it could be said thatNAPA creates a mathematical representation of the patches.

SEC {surface} marks the surface to be intersected, which can then be drawn in several ways. Forexample, using commands:

X D=0.5 draws sections in direction of X with an increment of 0.5 m

Y (0.6 7 0.2) direction Y ; from Y=0.6 to Y=7 ; increment 0.2 m

X #16 frame number 16 (frames defined in the reference system)

The following provides two examples of surfaces. These examples, however, are though quite theoreticalunless there is a real connection to practical hull definition. Even so, it isIt is recommended to examine thesebefore continuing to hull definitions.

CUR C1; X, 0

YZ (0, 2), (10, 2)

CUR C2; X, 10

YZ (0, 5), (10, 5)

CUR C3; Y, 0

XZ 0/, C1, C2

CUR C4; Y, 10

XZ 0/, C1, C2

SUR, SUR1, P

THR C1, C2, C3, C4

OUT, +Z

CUR C5; X, 0

YZ (0, 1), (10, 1)

CUR C6; X, 3


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YZ (0, 1), (10, 1)

CUR C7; X, 6

YZ (0, 2), (10, 2)

CUR C8; X, 7

YZ (0, 5), (10, 5)

CUR C9; X, 10

YZ (0, 5), (10, 5)

CUR C10; Y, 0

XZ <> C5, C6, C7, C8, C9

CUR C11; Y, 10

XZ <> C5, C6, C7, C8, C9

SUR, SUR2, P

THR C5, C6, C7, C8, C9, C10, C11

OUT, +Z

Let us now make some practical surface definitions by finishing the grid for which main curves were defined inthe previous chapter. It is possible to define the surface already at this stage, but the surface would probablybecome quite unfair because NAPA would have to divide the large area into several four-sided patches.NAPA's logic concerning how a surface has to be split does not necessarily fit in with the designer's idea of thesurface. We can, however, take a look at how the surface would behave in this case.

In the PATROL version of project P1234 we open up the HULLF surface in the Geometry Window.

6.1.1 Updating the HULLF

We select a curve by clicking with the middle button (or with the left and right button simultaneously ona two-button mouse) on the curve. The name of the selected curve can be found in the Object box andthe name of this object's parent in the Main Object box.


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By clicking on the green update button next to the Main Object Box, the main object, which is a surface,will be updated and prepared. After the surface has been prepared, it is possible to plot the patchstructure of the surface and its intersections.

Let us then update the surface by pressing the Update button . To see the result, we will have to

choose to see the surface as well as the grid. The blue plot surface button will have to be pressed

down. To see the x-sections of the surface, we should also press down the x-sections button before

we click on the draw button .

Note: Please keep an eye on the main window, as the preparation diagnostics appear there.

Note that the surface will be filled with a brown colour, and that the default increment between thex-sections is 1 metre. To change the drawing properties we can click on the Edit Drawing Properties

button to open the drawing properties dialogue.

Here you can turn off the filling used for the plotting of geometric objects by clicking in the check-box ofthat row. On the X Sects tab you can change the intersection interval to 0.5 metres. After closing theproperties dialogue you will have to click on the draw button again.


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The problem with this surface is the big area lacking control in the middle. There can be manyapproaches of to filling up the area with nice square like patches. Depending on what our starting pointwas, we might continue with water lines here as our main source of form for the surface, or we mightcontinue with some frames. In this example, we will continue with some frames that will be connectedby longitudinal secondary curves.

6.1.2 Entering frames curves

The next problem now is to select which frames to enter into our surface. Starting from the main frame(FRF), it is good to enter a frame quite close to the main frame. This is very easy to define, as it veryseldom needs any points other than the reference to the flat of side and the bottom tangent. The ideabehind such a curve is to stabilize the longitudinal curves (that will be defined later) and to give them agood direction when coming into the bilge radius.

The next frames will be chosen on the base of the areas that need support in the surface. These arethe end points of the FSF and the FBF. Using the curve/curve syntax, these curves are defined as beinglocatad at the x-planes in the end points. Please note the reference to the points in the form of thecurve. Both frames have been given two explicitly defined points, to give them the required shape.

The curves are added to the curve and surface definitions in the text editor. If the text from the earliersession was not saved, it is possible to recreate the definition from the curves in the data base byloading the definitions into the work area. This is done by writing >**HULLF into the object combo box.(See chapter 3 page 36 for an example)

Then we continue...

...

CUR FRF1; X 18.5

YZ FBF, FSF

CUR FRF2; X FSF/DECKF

YZ FBF, (2.17,0.6), (2.73,2.25), FSF/DECKF

CUR FRF3; X FBF/STEM

YZ FBF/STEM, (0.83,0.85), (1.46,2.63), DECKF

SUR, HULLF, P

THR FRF, STEM, DECKF, FSF, FBF, SN,

FRF1, FRF2, FRF3

OK

Clicking on the run button of the text editor and the draw button in the Geometry window will show usthe result:

6.1.3 Creating longitudinal lines

The next step in the process is to plan the longitudinal curves to be used. By looking at the grid inprojection X, we can do the initial planning. We know from the patch theory that the longitudinal curvesshould intersect the frames near the definition points and should connect other 'free' points of the gridinto the surface.


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Starting the planning we can 'see' three possible locations for longitudinal curves:

To create these longitudinal curves, we could enter the coordinates in the same way as when creatingthe frames, but there is a more interactive way to do so using the Geometry window and its clipboardfacility. Let us first locate the clipboard and try out its functionality before we define the longitudinal TFcurves.

The clipboard of the Geometry window is located at the end of the second row of tools in the tool bararea. Each time you click on the drawing area with the left button of the mouse, the coordinate pairrepresenting the position of the cursor in ship scale will be entered into the clipboard. Selecting a curvewith the middle button will enter the name of the curve into the clipboard. Clicking on the big red crosswill empty the clipboard.

To enter the TF1 curve into our surface definition, we will start by defining the beginning into theeditor:

...

cur tf1

yz

Then we will work with the Geometry window and show the coordinates of the location surface. This isdone by first clearing the clipboard and then clicking on the drawing, which should be in theX-projection. Because of the X-projection, the coordinate pairs will be YZ.

As we now have the two coordinate pairs needed for the location surface in the clipboard of theGeometry window, and as they are selected, we can paste them into the required position in the texteditor simply by locating the cursor in the wanted position and clicking on the middle button:


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cur tf1

yz (-0.101 1.003) (2.821, 0.473)

xy *hullf

To finalize the definition, we have added the line 'xy *hullf' to the editor.

The form of the TF1 curve will be taken as a reference for all curves in the HULLF surface. When this isrun, NAPA will open up the definition of the *HULLF statement and replace it with the curves of thesurface that are in fact intersected by this location surface. To see and append the curve as it has beendefined to the surface we can use the >TF1 syntax in the combo box of the editor or we can press theappend definition button and select the TF1 curve.

...

cur tf1

yz (-0.101 1.003) (2.821, 0.473)

xy *hullf

SUR, HULLF, P


FRF1, FRF2, FRF3

OK

CUR TF1

YZ, (-0.101 1.003) (2.821, 0.473)

XY FRF, FRF1, FRF2, FRF3, STEM

As you can now see, the curve will be appended at the end of the work area. Using cut and pastetechniques we can move it up and place it before the surface definition. At the same time, we can editit. For example the first position in the location surface (-0.101 1.003) can be replaced by an exactreference STEM/Z=1. The curve TF1 is also added to the surface.

CUR TF1

YZ, STEM/Z=1 (2.821, 0.473)

XY FRF, FRF1, FRF2, FRF3, STEM

SUR, HULLF, P


FRF1, FRF2, FRF3 TF1

OK

Using the same technique, we will add the curves TF2 and TF3 to the surface. NOTE: Use of thecurve/curve syntax to make exact positioning of the curves after the initial mouse positioning. To makethe forward end area work better, we will also add some angles in and around the stem area.Esspecially note the technique of entering the soft nose curve (SN) with a free angle and continuinginto the stem curve with a 90 degree angle.

CUR TF1

YZ, STEM/Z=1,(2.821,0.473)

XY FRF, FRF1, FRF2, FRF3, -25/, STEM

CUR TF2

YZ, STEM/SN, FRF/FSF

XY FRF/FSF, FRF1, FRF2, FRF3, STEM/SN

CUR TF3

YZ, (-0.051, 2.885), (1.513, 2.609), (2.78, 2.22), FSF/FRF1

XY FSF/FRF1, FRF2, FRF3, -/, SN,-90/ STEM

SUR, HULLF, P


FRF1, FRF2, FRF3 TF1, TF2, TF3

OK


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Examination of the fore body shows us that it now fulfils our requirements regarding this project .

6.1.4 Checking the surface using the Geometry Window

The upper row of tools in the tool bar of the Geometry Window is used to control the drawingproperties of the drawing area of the window. Starting from the left, we have the

Open button to open the active object for drawing

Object combo box, where the name of the active object can be written or selected from the list ofobjects that have been active this session

Plot the hull button to plot the surface. Note the default drawing property is to draw it with a brownfilling.


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Plot the grid, i.e. the curves that make the surface definition

Show the definition points

Show point objects

Show names of curves

Show x sections

Show y sections

Show z sections

Show curves of equal inclination

Show porcupine curves

Show porcupines on the selected curve

Erase the screen before drawing

Draw the object with the selected features

Edit the drawing properties

A good and simple way to check the fairness of a hull surface is to intersect the hull and to use thespecial feature of colouring according to the curvature of the intersections. In command mode the,command to set this up with is col *. Using the Geometry window, the same can be achieved by settingup the drawing properties.

We click the Drawing properties button and select the X sections tab.

Here we can set the colour of the sections to section curvature and the step between sections to 0.1

When we now close the properties window and draw the picture again with the x-sections selected, wecan see the curvature of the sections of the surface. The different shades of red and blue representdifferent levels of curvature. White represents straight lines within the tolerance.


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6.1.5 Editing curves using the Geometry Window

Curves can be edited by editing the coordinates directly in the text editor through which we have donethe definition, but the Geometry window can also be used to edit and modify curves directly.

Editing of surfaces and curves is controlled with the tools in the lower row of the tool bar. Selecting of acurve to edit is done by pointing to the curve and clicking on the middle button of the mouse. Theobject to edit is shown in the object box.

By clicking on the 'edit object' button or the 'append object to editor' button a text editor window willopen with the object definition in it. Changes in this window are activated by pressing the run button

of the editor.

Another way to edit the curve is to click on the 'Open curve editor tool' button. This will open theinteractive curve editor:

The interactive curve editor allows the user to edit the curve by editing the points directly in thedefinition area of the window. By clicking on the apply button the change will be available in thedrawing area of the Geometry Window. The Move button allows the user interactively to move explicitdefinition points in the shape of the curve, using a drag event. Before clicking on the Move button theprojection should be set to X, as we will be moving YZ coordinates of this curve. By pressing the leftbutton on the mouse and dragging we can move the explicit definition points. To end the 'move-mode',the right mouse button must be clicked on the mouse. The Add and Delete button can be usedsimilarly. Please note that the current definition will also change in the text area of the curve editorwindow.


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Note: as long as the curve editor window is open, all changes to this curve can be undone one by oneby clicking on the undo button, or we can return to the original curve (before the editing session) byclicking the cancel button. More than one curve editor tool can be open simultaneously.

After an interactive (or after any kind of change, in fact) we will have to click on the update button inthe Geometry Window to have the secondary curves updated and the preparation done.

Note: If a curve has been changed interactively with the edit curve tool, the text in the text editor isstill unchanged. Use cut and paste techniques to update the text from the curve definitions into the texteditor.

6.1.6 Creating the HULLA

We will define the curves of the aft ship in a similar manner as the curves of the fore ship. We willdefine the main curves of the aft ship in the text editor:

cur fra; x, 13

yz (0, 0), -/, (1.8, 0), (3, 1.2), /-, (3, 4.4)

sc , m

cur stern; y, 0

xz (-2.6, 4.4), -/, (-2, 2.2), /-, -/, (1.8, 1.3),

/-, -/, (2.7, 0), /-, fra

cur decka; z, 4.4

xy stern, -/, (-2.6, 3), /-, fra

cur transom

xz, (-2.6, 4.4), (-2, 2.2)

yz stern/z=2.2, -/, (2.4, 2.4), (3, 3), /-, decka/y=3

sc , -//-

cur fsa; y, 3

xz transom/z=3, 0/, fra/z=1.2

sc , p

cur fba; z, 0

xy 15/, stern/x=2.7, (4, 0.3), /-, -/, (10, 0.3), /-,

0/, fra/y=1.8

sur hulla

thr fra stern decka transom fsa fba

In the following, two figures illustrate the definition of curves FBA, FRA and TRANSOM.


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The usual method of defining a surface grid is to define all main curves first. In our case, the knucklecurve between the skeg and the rest of the hull has not yet been defined, so we will continue bydefining this knuckle curve.

This kind of hull with a knuckle between the skeg and the main surface, would be better defined as atrimmed surface, in which the skeg and the other part of the hull are first defined separately andthen combined to form one surface. We will, however, define this hull in the traditional way, and willdeal with an example of the trimmed surface later.

To be able to define the knuckle curve, we need to know the angle of the STERN curve between thetransom and skeg. This can be checked with the command LIST STERN in the command input area ofthe main window.

DEF?>lis stern

LIST OF CURVE: STERN

**************************************

X Y Z T SC REF.CURVE

-2.600 0.000 4.400 -74.75

-2.000 2.200 -74.75 -/

-13.32 /-

1.800 1.300 -13.32 -/

-55.31 /-

2.700 0.000 -55.31 -/

0.00 /-

13.000 0.000 0.00 (M/) FRA


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cur ta1

xz stern/x=1.8, /-13.3 fba/x=10

xy 15/ stern/x=1.8 (3.1, 0.3) /- fba

sc -//-

The next curve to be defined is the frame located at the end point of the skeg. Note that a free angle(-/) will be needed because the flat bottom is defined without the side condition P. We will start it fromthe STERN curve, as this will cut the flat bottom area into four-sided patches.

cur fra3

x 10

yz stern -/ fba fsa

The next step to be taken is to define a frame at the starting point of the skeg. It is, however,impossible to define this curve without having some support for it. One possibility would be simply toadd a point to the curve, but the point would need manual adjustment later at the fairing stage. Aclearly a better solution would be first to define a space curve from the transom to the main frame anduse it to give the needed support to the frame.

cur ta2

xz transom/y=2.4 /-13.3 fra/z=0.6

xy transom fra3 fra

As we have now created space curve TA2, we can define curve FRA1 through this curve. The startingangle from STERN will be the same as TRANSOM (5 degrees).

cur fra1


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x 1.8

yz stern /5 ta2 fsa

Now it can be seen that we still have a couple of definition points in need of support. What we will donext is to define a 'frame' with a knuckle on its location surface. Below the knuckle line (TA1) thelocation surface will be inclined while above the knuckle it will be on the X-plane. One factor causing ussome trouble is the angle at which the new frame has to enter TA2. If no angle condition is given, theframe would without doubt hang much too low in the area between TA1 and TA2. We could check theangles at which frames FRA1 and FRA3 enter TA2 and then, by trial and error, we could search for theright angle. But on the other hand, why should we do such manual work as we can let NAPA do thework for us? The easiest way is to define a tangent function for TA2 and then let the tangent functiondefine the angle in question.

tgf ta2

xt transom fra1 fra3 fra

cur fra2

zx <> (4 0) ta1/x=3.1 (3.1 10)

zy stern -/ fba /- ta1 */ ta2 fsa

Note that in the definition of FRA2, no free angles entering/leaving were needed when referring tocurve TA1. This is because TA1 was defined with the side condition SC -//- (a knuckle). If, however, wewanted to define an angle condition at either side, then the side condition would be neglected and wewould also be forced to define the free angle explicitly. For example ... -/, TA1, /15, ...

The last thing we need to do to finish the grid is to split the five-sided transom into two patches inorder to avoid the automatic splitting which takes place when a patch has more than four sides. If NAPAis allowed to take care of the splitting automatically, you cannot be completely sure about the result.

cur ta3

z transom/fsa

yx stern -/ transom

sur hulla

thr fra stern decka transom fsa fba ta1 fra3 ta2 fra1 fra2 ta3

ok


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As the grid is now ready, it is time to check the fairness of the surface.

This time we will use the command language to check the fairness of the hull. This can be done bydrawing sections in different projections. The colouring with drawing command COL * is a very effectivetool for the purpose.

DEF?>upd hulla

DEF?>pre hulla

DEF?>sec hulla

DR?>col *

Although the surface might still need some fairing before steel production, it is good enough for projectpurposes. We only need to define the parallel mid body and, after combining the parts, we have acompleted hull to proceed with our project. Note that the FRA and FRF are already defined in the HULLAand HULLF definitions.

cur clm; y 0


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xz fra frf

cur deckm; z 4.4

xy fra frf

cur fsm; z 1.2

xy fra frf

cur fbm; y 1.8

xz fra frf

sur hullm

thr fra frf clm deckm fsm fbm

sur hull

com hulla hullm hullf

ok

Note that the combined HULL suface has to be prepared before we can use it for intersections etc. Thiscan be done by writing HULL in the main object combo box and then clicking on the update button, orby giving the following command sequence in the command input area of the main window:

DEF?>upd hull

DEF?>pre hull

6.2 Some useful drawing commands

In this chapter will look at the commands that control graphics in NAPA. Most of the tasks can also beperformed interactively through the Geometry Window, but the use of commands is necessary for writingmacros.

Note that in the following, the commands are explained very briefly. For a more thorough explanation, see theexplanation texts with the command !EXPL or by using the Help Viewer.

For the plotting of arrangement drawings, the commands SETUP and DRW are provided. SETUP defines asystem of plans and generates a layout for showing them, while DRW draw objects in these plans. Thesefunctions are described in more detail in connection with the chapter 'Ship Model'.

6.2.1 Drawing environment

PROJECTION Defines how the 3D objects are projected onto the 2D drawing area. The mainalternatives are: PRO X projection along the x-axis PRO Y projection along the y-axisPRO Z projection along the z-axis PRO A predefined perspective projection from aft PROF predefined perspective projection from fore PRO phi,theta arbitrary parallel projectionThe projection can also be defined interactively (PRO I), in which case it can bechanged by moving the mouse while the left button is held down. The object can bemoved with the centre button of the mouse and the right button ends the interactivesession.


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SIZE Generates the scale and position of a drawn result so that a given region in the shipcoordinate system fits the screen. There are several ways to give the region: ´SIZE Ssize of the ship (from REF task) SIZE F size of the fore body SIZE A size of the aft bodySIZE name size of the given object, e.g. SIZE HULLF SIZExmin,xmax,ymin,ymax,zmin,zmax size given explicitly SIZE * size of the currentlyintersected object The command SIZE without any options shows the current setting.

DRAWING Starts a new drawing; it clears any graphics on the screen and resets all controlparameters. It assigns a name to the drawing, which is relevant when storing it. Forexample: DRA FRAMES

!VIEW 3D In the 3D mode, the internal graphics storage is maintained in a way that allows it tobe adapted to the changed SIZE and projection. In this mode, these changes haveimmediate effect.

!VIEW 2D Turns 2D mode on.

6.2.2 Output commands

PLOT An object can be plotted with the command PLOT (for example, PLOT STEM. When asurface is plotted, the patch representation of the surface will be drawn (for example, PLOTHULLF).

GRID Plot the grid curves of a surface, e.g. GRI HULLF

X,Y,Z Plot sections of the object(s) made active with the command SECT. For example: SECTHULL; X 50

TEXT Plot a given text at a given position. The text can be controlled by the commands TCOL,FONT and TH.

FIG Plot a figure (figure = a stored drawing)

POL Plot a polygon through given points. For example:POL (1 2) (4 4)draws a straight line between the pointsPOL / (1 2) (4 4)draws a box between the pointsPOL : the points are to be shown with the mousePOL I the same as POL : but interactive

NET Plot a coordinate grid.

FSCALE Plot a frame scale.

6.2.3 Drawing options (control commands)

COLOUR Set the colour of lines. For example, COL 2 or COL red

COLOUR * Set a special colouring mode where the curvature is expressed in shades of red andblue. This gives a fast way of estimating the fairness of a curve or a surface.

DASH Set dash pattern, 1=solid line, 2,3,...=various patterns

THICKNESS Set line thickness (1,2...)

FILL Fill colour for closed curves (colour index or logical fill code). E.g. FILL 3 or FILL c-hfo

ID Identification mode. The most usual identification options are:ID P points, both defined and intersectionsID D definition pointsID NAME name of objects

ID2 Second identification. The same as ID but two identifications can be usedsimultaneously.

ID OFF Cancel identification.

TCOL Set text colour.

FONT Set font type.


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TH Set height of the text.

6.2.4 General services

!ZOOM Zoom into the drawing. The zoom area can be defined explicitly (e.g. !ZOOM 20 25 5 1510 15) or graphically with the mouse (e.g. !ZOOM : or !ZOOM I).

!SEND Make a hardcopy of the current drawing or save it to the database. Examples:!SEND TO P1 !SEND TO IOF !SEND TO DB4Several options available. See the on-line explanation text.

AUTO In AUTO mode, curves are drawn automatically when defined or modified.

AUTO OFF Cancel AUTO mode.

ARGS Show the current arguments.

6.2.5 Examples

The following example will create a profile view of our hull with buttock lines intersected at 10 cmintervals. Note that the drawing will be created in an active drawing area when the macro is run. If nodrawing area is active, a separate default drawing window will be opened.

dr

sec hull

pro y

siz *

y d=0.1

plo decka deckm deckf

Note the command SIZ * which was used above. This command sets the size of the drawing to fit theobject currently selected for intersections (SECT HULL).

In this example we will make a traditional frame drawing and send it turned to the default printer inscale 1/100.

dr

sec hull

pro x

ref x<15

siz *

x d=0.5

y 0

!send d t scale=.01


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We have used the command REF X<15, which means that all parts (both sections and curves) locatingat x<15 metres will be drawn to the negative side of the y-plane as a reflection.

6.3 Special surfaces

In this chapter we will examine special surfaces of NAPA but with only a few words; the examples will speakfor themselves. By default the special surfaces will be facet surfaces i.e. made out of straight plane parts. Byusing the option P when defining the special surface, the surface will be created as true PATCH surfaces.

6.3.1 Plane

The first special surface is a plane, which can be defined in many different ways. For example:

PLANE P1 ; X 10 Plane parallel with a coordinate plane.

PLANE P2 ; THR Y (-3,0) (-1,3)

Plane parallel with the y-axis, defined with twocoordinates.

PLANE P3 ; THR Y (-3,0) 56

Plane parallel with y-axis, defined with onecoordinate and an angle (56 degrees).

PLANE P4 ; THR (8,0,0) (6,8,0) (7,8,5)

Arbitrary plane defined by three points

PLANE P5 ; THR 5 -1 10

(Water) plane defined as draught, trim heel

6.3.2 Cylinder

If the cylinder ends are closed, the optional CLOSE command adds the ends, making a closed surface.


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CYL, TUNNEL

AXIS, (74.2, -5, 1.4), (74.2, 5, 1.4)

FORM, R=0.6

CLOSE

A cylinder can also be formed so that a curve, the generator, is moved along another curve, the basecurve. The base curve can be defined as an independent curve or by an imbedded curve definition, as inthe example below.

CYL, DECK

Y, -16

XZ, ><, (-5, 10), (100, 10), (100, 13), (130, 13)

GEN, Y, 32

6.3.3 Double Cylinder

A double cylinder differs from a simple one in that the generator can also be curved.NOTE: The generator is placed so that its origin moves along the base curve.

CUR GENERATOR; X, 0

YZ (-16, -1), (0, 0), (16, -1)

CUR BASE; Y, 0

XZ (-5, 10), (50, 9), -/, (100, 11), /-, -/, (100,

14), /-, (110, 14.4), (130, 15)

DCY, DECK

BASE, BASE

GEN, GENERATOR


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6.3.4 Tube

A tube object is formed when a given shape is moved along a given curve, turning the shape as thebase curve turns. The turning makes this type differ from the double cylinder (DCYL). The tube objectcan typically be used to model tubes or ducts etc.

A tube is defined by the records BASE + FORM, where BASE gives the reference curve and FORM thecross-section

CUR BASE

XYZ (0,0,0), (5,2,0), (10,5,5)

TUB, TUBE

BAS, BASE

FOR, R=1

TUB, DUCT

XYZ, ><, (0, 0, 0), (10, 0, 0), (10, 0, 2), (13, 0, 2)

FOR, /, (-0.5, -0.2), (0.5, 0.2)

6.3.5 Connection Surface

A connection surface is formed when points on two curves are connected pairwise. As with the othertypes, the curves can be defined separately (as in the example below) or imbedded in the surface


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definition.

For the connection surface to work, the curves must be sufficiently similar (analogous startpoints, samerotation direction).

CUR BASE1; Z, 3.8

XY 5/, (-1.4, 0), -5/, (0.3, 0.15), -90/, (0.6, 0)

CUR BASE2; Z, 0.4

XY 5/, (-1.2, 0), -5/, (0.25, 0.13), -90/, (0.5, 0)

CNS, CNSUR

BASE, BASE1

BASE, BASE2

6.3.6 Sphere

SPH, SPHERE

CENTER,(3, 0, 3), R=2

6.3.7 Rotation Surface

A rotation surface is formed when a curve is rotated around a given axis.

By default, the base is rotated 360 degrees. Another angle can be specified in the AXIS command.

CUR BASE; X, 3

YZ * 30/, (0.5, 0.5), (2, 4)

ROT, ROTSUR

AXIS, (3, 0, 0), (3, 0, 10)

BASE, BASE


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6.3.8 Pyramid

A pyramid is formed when the points on a curve, the base, are connected to a given point, the top. Ifthe base is closed, it can be included by adding the optional CLOSE command. If the base curve is acircle, the result is a cone.

CUR BASE; Z, 0

XY * <> (2, 2), (6, 2), (6, -2), (2, -2), (2, 2)

PYR, PYRAMID

BASE, BASE

TOP, (4, 0, 4)

6.3.9 Facet Surface

A facet surface can be defined through a set of n*m points. Four neighbouring points are connected tothe sides of a plane. A three-sided facet can be formed by adding coinciding points. If the pointsforming a facet do not lie on the same plane, a warning is given, but the result is accepted.


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6.3.10 Examples (Patrol)

The following example defines the internal planes, cylinders and double cylinders that are used in thedefinition of the P1234 version PATROL.

PLA, BH1

X, 5

PLA, BH2

X, 9

PLA, BH3

X, 17

PLA, BH4

X, 26

CUR CAMBER; X 0

YZ (-3.5,-0.15), (0,0), (3.5,-0.15)

CUR SHEAR; Y 0

XZ (-3,3.8), /-1, (34,4.4)

DCY, DECK, P

BAS, CAMBER

GEN, SHEAR

CYL, TTOP

Y, -4

XZ, ><, (-3, 1.7), (5, 1.7), (5, 1), (9, 1), (9, 0.6), (26,

0.6), (26, 1.7), (35, 1.7)

GEN, Y, +8

CUR BRFOREBASE; Z 0


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YX (-0.4,-3), (0,0), (-0.4,3)

CUR BRFOREGEN; Y 0

ZX <> (17.7,3.6), (17.1,5.6), (17.4,6.7), (17.1,7)

DCY, BRFORE

BASE, BRFOREBASE

GEN, BRFOREGEN

CYL, BRAFT

Y, -3

XZ, ><, (8.9, 3.6), (10.5, 7)

GEN, Y, 6

PLA, BRSIDE

THR, (-, 2.3, 3.7), (-, 2, 7)

PLA BRTOP

Z 7


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Documents

3. NAPA Online Manuals 2009