CINEMA 4D

Transcription

CINEMA 4D

CINEMA 4D
SPLINES AND EDITS • NURBS TOOLS USE • MODELING TOOLS
5.1 SPLINES
Cinema has very good toolset for editing splines. Splines are
very useful for creating models. Especially Splines with Nurbs
tools can make work on complicated models much easier. Very
complex curves can be imported from Adobe Illustrator native
format *.AI
Splines are located in menu Objects or with their icons in main
TOOLBAR.
Splines are primarily a sequence of vertices, connected
by lines, lying in 3D space. The shape of these connecting
lines (straight or curved) defines the interpolation.
Apart from the direct connection of the vertices with
straight, rigid lines, there are other kinds of splines that
use an interpolation method where the lines between the
vertices are curved instead of straight. These splines have a soft leading edge without
sharp corners.
The spline itself is infinitely thin. They have some thickness for visibility in a viewport.
A spline is not visible when rendered.
The spline’s line has no three-dimensional depth, even though it occupies
the 3D space. However, many complex 3D objects, among other things, can
be constructed in seconds out of these curves by using them with NURBS
objects.
After the spline is created it can be pulled along its depth in order to make tubelike objects. You can also rotate a spline around an axis to create objects that have
rotational symmetry, such as wineglasses. Or you can construct a skin over several
splines, with the finished object simulating the contours on a map. More of these
spline-modeling capabilities are discussed in the NURBS section.
To create a new spline curve:
From menu Objects > Spline to create an empty spline.
- Select mode for POINT EDIT and use tool MOVE with icon or from menu
TOOLS
Create points for the spline by Ctrl-clicking in each place where you want to create a
point. The first point defines the start of the spline.
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• If you Ctrl-click on the curve between two existing points, the new point will be
placed on the spline between the points.
• If you hold down the Shift and Ctrl keys while clicking, the new point will be created
at the beginning of the spline, giving a new starting point.
If the Close Spline option is enabled and you Ctrl-click the starting point, the
spline will be closed.
• Position of curve points can be adjusted with tool MOVE. For multiple selection hold
Shift and LMB.
• The spline is always created in the view of the active viewport. For FRONT VIEW
will be created in XY plane. In TOPVIEW in XZ plane. In the perspective view, the
freehand spline will be created on the plane that is perpendicular to the camera
direction.
For some operations, such as the aligning of objects along a spline (Arrange
command) or the movement of objects along a given curve (Align To Spline tag), the
direction of the spline (where it begins and ends) is important. For this reason, the
spline is color-coded. By default, from the first vertex, the starting point, and
moving outwards, the curve is colored from yellow to orange to red (the end
point). This colored display is visible only when the Points tool is active.
Segments
A spline is made from several partial curves, or
segments. For example, if you create some text, you
will see that only one object is created, even though
you typed in several letters. The text object now
consists of several outlines — one outline or more
per letter. Even when converted to editable it is still
only one object.
For example, the word ‘Test’ consists of four letters;
that makes four separate segments. However,
another, fifth, segment is also present — the inside
of the ‘e’ is a further spline segment. If this type
of element is later extruded to form a 3D object,
CINEMA 4D will automatically punch out a hole that
is the same size and shape of the internal segment of
the ‘e’.
Holes are formed only if a spline lies completely inside another spline and both form
closed curves. If two segments overlap in any way, no 3D object can be formed.
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Do not confuse the Polygon object with the Spline object. Although both are
essentially just empty containers, the former consists of polygon vertices only while
the latter is made up of spline vertices (and splines).
To create a new spline segment
Add a new point that will be the start point of a new segment (initially, this new point
will be connected to the last point of the previous segment).
Choose Structure > Edit Spline > Break Segment The connection to the
previous segment is now broken. Add further vertices. All new vertices now belong
to the new segment. You can create further segments. If we need first vertex of new
segment to be in the same position as the last vertex of segment created before we
can use move tool. If a spline consists of several segments, then new vertices are
always created from the active vertex. If no vertices are active, then new vertices are
generated at the last-created segment. If several vertices at different segments are
active, new vertices are always generated at the first-created segment.
Attribute manager - Settings for SPLINE
OBJECT PROPERTIES > TYPE
Linear
This simplest of all the spline types connects the vertices,
which define the polygon, with straight, directly connected
lines. You can use these splines to create angular objects
or to simulate sharp jerky movements for animation.
Cubic
This kind of spline has a soft curve between vertices. The
interpolated curve passes directly through the vertices.
Looking at the two points at the top right of the diagram,
you can see that the curve bulges more than is probably
required. This behavior is called overshooting, and it often
appears with closed curvatures. This becomes clearer
when you compare this section of the curve with the same
section of the curve with Akima interpolation.
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Akima
This spline type creates a soft curve between vertices.
The interpolated curve always passes directly through the
vertices. Overshooting does not happen with this type of
curve.
B-Spline
This kind of spline also creates a soft curve between
the vertices. However, the curve does not pass directly
through the vertices. This produces a very smooth curve.
The vertices control only the approximate path of the
curve. Distant points have less influence on the curve
than those lying closer together. Control points are also
endpoints of tangents of this spline, derivation of shape.
This type of curve belongs to the NURBS.
Bezier
This spline type creates a soft curve path between the
vertices, which can be controlled very precisely. The
interpolated curve always passes through the vertices.
Overshoot does not happen. This interpolation is based
on NURBS geometry, shape is controlled with tangents.
Tangents are in control points and defines force affecting
the shape. Bezier splines are offering the most control.
Working with a Bezier spline and its tangents
If you activate a vertex of the spline (i.e. by clicking on it), additional control points
at the tangents to the curve become visible. With MOVE tool and LMB we can drag
the tangent end point. Changing the direction of the tangent handles controls the
direction of the curve at each vertex. By adjusting the length of these tangent
handles, you can control the strength of the curvature. Drag the tangent end point
towards the vertex point and observe the symmetrical movement of the opposite
handle.
You can change the lengths of the tangents separately
from each other. To do this, Shift-drag a tangent end
point.
You may set different tangent directions on the
right and on the left of the vertex. To do this, Shiftdrag a tangent end point. With this approach you can
make the otherwise smooth path of a curve produce
sharp corners and peaks.
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If the tangents of two neighboring points have zero
length, the segment that runs between the vertices
will be linear. Thus, you can mix linear segments
with curved spline shapes.
If you double-click on a Bezier vertex with the
Move, Scale or Rotate tool active, a dialog opens
that allows you to accurately enter both the position
of the vertex (in the spline’s object coordinates) and the position of the tangent
end points (relative to the vertex) numerically. If you convert a Bezier spline to a
different type of spline, all tangent settings will be lost. If a spline is converted from
a non-Bezier type to a Bezier type, all tangents will be assigned default positions and
orientations.
OBJECT PROPERTIES - Close spline
Each spline segment can be closed or open. If
a spline is closed, the start and end points are
connected. There is a big difference between
closing a spline (and interconnecting the start
and end points) and simply positioning the start and end points together. In the first
case, the transition from the start to the end point is soft, in the second case it is
abrupt. To close the spline, Ctrl-click the start point or use option CLOSE SPLINE in
Attribute manager.
INTERMEDIATE POINTS, ANGLE
Here you can define how the spline is further
subdivided with intermediate points. This affects the
number of subdivisions created when using the spline
with NURBS objects.
We will describe two basic modes:
NONE
This method of interpolation locates points only at the
vertices of a spline, using no additional intermediate
points. You cannot enter values into the Number or
Angle boxes.
NATURAL
This interpolation type divides spline by number of
points in number box. The points are positioned closer
together on areas of the spline with more curvature.
You cannot enter values into the Angle box. The
interpolation is not affected by reversing the point order.
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Create Spline (Curves)
The Spline object allows you to
quickly create new splines from
scratch. However, for some shapes
this approach can be clumsy and
unnecessary. For this reason CINEMA
4D includes spline curves. These are
interactive tools that remain active
until you select another tool, such as
Move. You can thus create any number
of these splines without the need to
select the command each time.
Splines are created in active viewport.
Freehand
You can use this command to draw curves directly in the viewports. Select the
Freehand tool, then click in a viewport and keep the mouse button pressed. You
can then draw the Freehand curve for as long as the mouse button is held down.
Releasing the mouse button will end the Freehand spline creation and the finished
spline will appear. (This is especially useful when tracing patterns with a graphics
tablet.)
• Freehand Splines are always created on the camera plane when you work in the
perspective views, not on the construction plane, which is the case for the Bezier, BSpline, Cubic, Akima and Linear splines. If you want to draw a spline onto one plane
(XY, ZY, XZ etc.) you should switch to the corresponding view.
Bezier, B-Spline, Linear, Cubic, Akima
Using these commands, you can create the exact type of curve you require. Choose
the desired spline type. Point editing mode is activated automatically. Click to create
each point. Once you’ve added the desired points, either click the starting point to
close the curve or press Esc to exit the mode. You can then edit the spline in the
usual way (drag to move a point; Ctrl-click to create a new point, etc.).
With these functions we create spline with interpolation. Differences are discussed
at the beginning of this chapter. To end editing press Esc. Other editing functions are
same as for Spline object .
.
• You can alternatively create the points in the same way as for the Spline object.
After choosing the command, rather than clicking to create points, use Ctrl-click
instead; to move a point, drag it; to close the spline, click the starting point
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5.2 SPLINE PRIMITIVES
CINEMA 4D gives you a generous number of predefined curves. Add to this the
possibility to convert vector based artwork files from other programs (see ‘Vectorizer’)
and to add graphic characters (see ‘Text’) and you have a wealth of spline primitives
at your fingertips. All of these spline primitives are parameterized. This means that
the spline is merely the graphical representation of a mathematical formula built
controlled by parameters you can edit the Attribute manager.
As a result, this mathematical formula initially has no properties to edit within the 3D
viewport. It has no vertices to manipulate. To adjust the vertices with the Points tool,
for example, you must first make the spline editable (Structure > Make Editable).
Then spline is not parameterized anymore and act as normal curve. You can, however,
apply deformer objects or NURBS TOOLS to the spline even if the spline has not been
made editable.
When creating a new spline primitive from the OBJECTS menu, the spline appears in
the viewports and its parameters are displayed in the Attribute manager where you
can set various curve parameters. Let’s try some of them.
Object properties
Common settings
Some of the spline settings are present for each type
of primitive. These common properties are described in
this section.
These settings are PLANE, point order - Reverse
interpolation of curve Intermediate points, Number,
Angle
Use this drop-down list to define in which of the three
planes (XY, XZ, ZY) the spline primitive is to lie. By
default the spline is always positioned so that it is
visible in the current active view.
This means that if the spline is created in the XZ (top) or XY (front) view, then the
spline will be seen, for example, as facing towards the XY plane in the 3D viewport.
In each of the following examples the spline primitive has been created in the frontal
view (XY plane).
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Reverse
If this option is enabled, the order of the points is reversed. Reversing the points of
the spline primitive not only has an effect after the conversion to an editable spline
curve. The reversal of points also affects commands such as Align to Spline
Intermediate Points, Number, Angle
These interpolation settings define exactly how finely the vertices of a spline will be
positioned. The various choices are described earlier in this chapter.
Some spline primitives
Arc
This command creates arc elements..
Type
With this option you choose the circle element to
be used in your arc. Choose from ARC, SECTOR,
SEGMENT, RING
Radius
Defines the circle radius from which the circular
element is to be created.
Inner Radius
If you set Type to Ring, this defines the inner radius of the ring.
Start / End Angle
Using these two values you can define the start and end point of the arc element. 0°
defines the value as the positive X-axis, 90° the positive Y-axis, 180° the negative
X-axis, etc. These examples assume you are working in the XY plane, as mentioned
earlier.
Cogwheel - This command creates a cogwheel.
Teeth - Defines the number of teeth for the
cogwheel.. Minimum value is 5
Inner, Middle, Outer Radius
The overall size of the cogwheel is defined by Outer
Radius, while Inner Radius defines the depth of
the teeth. For avid mathematicians: Depth of teeth
= (outer radius – inner radius). The third value,
Middle Radius, gives the height at which any bevel
will start to take effect
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5.3 SPLINE EDITS
Tools for editing of curves are located in top menu
Menu > Structure > Edit Spline
• You must first make spline primitive editable
Hard / Soft Interpolation
This command switches all selected points to hard/soft
interpolation. If no points are selected, all points of the
spline are automatically changed to hard interpolation. Hard
interpolation means that the tangents of the appropriate points
are set to a length of zero. Soft interpolation means that the
tangents of the appropriate points are set to a standard length
and direction.
• Could not be applied for B-Spline
Equal tangent length
•This command can be applied to Bezier Splines only. All other types of spline have
preset interpolation which cannot be changed..
For each selected point, the shorter tangent handle is set to the same length as its
partner tangent. If no points are selected, all points are automatically included in the
action.
Equal tangent direction
•This command can be applied to Bezier Splines only.
All other types of spline have preset interpolation which
cannot be changed.
Tangent is usually controlled with the handles for each
control point. If one tangent is not set properly you can
move handle independently with the Shift key to fix this
problem.
Tangents of selected points have same direction so are
forming a line. If no points are selected, all tangents will
have the same direction.
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Join Segment
A spline can consist of several unconnected segments
(a text spline is a good example of this). If you want
to connect two of these segments, select one or more
points of each segment and use the Join Segment
command. The start points of each spline are joined to
the end points of the other spline. If you directly select
the end points of the two segments, however, these are
also joined. If these end points have the same position,
one of them will be deleted when joining.
You can join either two or all segments at the same
time. If more than two segments are selected then
only the first two are joined. If no points are selected,
all segments of a spline are joined.
Break Segments
• This command requires a point selection and works in
point mode only.
With this command, you can create a new spline
segment. Select one of the points that you want to separate. After using Break
Segment, you will have a new segment and all points on either side of the separated
segment will become a new segment. If the selected points are not consecutive, a
number of spline segments will be created.
To add a new segment to an existing spline, you must first create the first point of
the new segment. Before the break, it is still connected to the old segment. If you
now use Break Segment then the new segment will start here; you can now add new
points using the Add Points command. This function works only with points selected
and you must be in POINT EDIT MODE
Explode Segments
Using this command, you can split the individual segments of a spline into separate
objects. An individual spline object is created from each segment of the original. Only
the first segment of the original spline remains. You do not need to have a selection
and you do not need to be in point mode. The new spline objects become sub-objects
of the original spline and are given the names ‘<objectname>.<number>’.
For example, a text spline object can easily be split into individual letters.
(Keep in mind that certain letters, such as ‘e’, may be exploded into two or more
segments because of their holes. You may want to group these segments to
re-create the entire letter.)
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Set first point
• This command requires a point selection and works in point mode only.
When you choose this command, the selected point of a spline is defined as the
new start point of the spline and the remaining points are re-sorted accordingly. If
there are several segments within the spline, you can select multiple points within
each segment; each segment will be re-ordered according to the chosen points. If
more than one point per segment is selected, the first point within the spline order is
defined as the start point. Remember that the start of a spline is colored yellow while
the end is reddish in color.
Reverse sequence
This reverse the point order of a segment (i.e. make the first point the last point,
the last point the first point and re-order all intervening points), select one or more
points of the segment and choose Reverse Sequence. You can also apply this option
simultaneously to several segments by Shift-selecting the points of these segments. If
no points are selected, the sequence of the complete spline (and all of its segments)
is reversed.
Move Up / Down sequence
With Move Down Sequence, the sequence number of each point is incremented and
the last point of the original sequence will be the first point in the new sequence.
(Points doesn‘t need to be selected) With Move Up Sequence, the sequence number of
each point is decremented.
Chamfer
Chamfer is an interactive tool. This means you control the tool directly with the
mouse; select the tool then drag left or right within the viewport. Chamfer converts
each selected point to two points with soft interpolation between them. Using this
you can very quickly create rounded corners of a square. Only the selected points are
chamfered. If no points are selected, all connected points of a spline are chamfered.
For an open spline, the start and end points will not be included in the chamfer. If a
point possesses tangents then these will be set to zero before chamfering.
Crossection
• The splines must be selected in the Object
manager.
With this interactive tool, you can create cross
sections for a group of splines; we’ll refer to
these as ‘rail splines’.
Cross sections are always created at right angles
to the current view. You should therefore select a
view in which you can see the rail splines directly
from the side, top or front.
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If you activate the Cross Section tool, you can drag to draw a line where a cross
section is to be created.
Three cross-sections have been created. In the 3D viewport you can that this has
created circles (more or less) that are wrapped around the three rail splines. These
cross sections are Bezier type splines. These cross sections are especially useful
when used as children of a Loft NURBS object. The order of these rail splines is
important. When working with more than two rail splines, make sure that these are
placed in the correct order within themselves in the Object manager, because C4d
uses this object order when creating the cross sections. The start point of the cross
section spline is located on the first rail spline and the end point on the last.
Project
• The accuracy of the projected spline depends on two factors: how finely the spline
is subdivided (the Project function does not add new points) and the alignment of the
splines to the surface. For best results, use a Bezier spline.
Using this command, you can project splines onto object surfaces.
Project automatically converts procedural splines to editable splines. Please note that
this step is not reversible (although you can, of course, use the Undo function). Each
point of a spline is individually projected. If a point cannot be projected (e.g. because
no surface is available for it), then it will remain at its original position. With Bezier
splines, the tangents are adapted to fit the surface.
Projection
Use this dialog to choose the type of
projection. CINEMA 4D projects the spline
onto all visible surfaces (hide the surfaces
of any objects that you want to exclude
from the projection).
View
Projects the points according to the current
view in the viewport.
XY, ZY, XZ - The spline is projected according to the selected plane (the points are
moved perpendicular to the plane, onto the object).
Radial XY, ZY, XZ
With Radial the spline is projected spherically, outwards from the object coordinate
origin of the spline. If several intersections are found, then the furthest one is used.
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5.4 MODELING with SPLINES using NURBS TOOLS
In this chapter we will demonstrate how to use LATHE (NURBS rotation) function.
Lathe is basic method used to create rotational objects. This object is defined with
basic spline which is rotated around Y-axis of the local axis system.
Let‘s use LINEAR SPLINE either from Objects Menu, or from
Spline palettes from Top TOOLBAR. Cursor is changed to an
arrow with Curve symbol which indicates selected tool, click to
the viewport to add the first point of the curve. Add more points
to create curve similar to the one shown on the picture. Finish
edit mode by clicking selection tool (arrow) from Toolbar
Position and point alignment can be done with Coordinates
manager. Another method is use of the tool Set Point Value
set the values of the selected points
Select points which we need to align or set value and from the
menu
Structure > Set Point Value
Leave The point coordinates will not be changed for
the respective axis.
Set Sets the point coordinates to the Val value along
the respective axis.
Center
Centers the points along the respective axis.
Coordinate system sets Coordinate system which is
used.
If we are done with basic curve, click into the viewport to deselect all points. Rightclick to get available Tools menu and select tool Create Outline at the bottom of
this menu.
This tool creates outline of our curve but can create also outline of polygon object.
Drag mouse left to create offset curve which is connected with the original curve. You
can also create new independent curve too (settings in menu Active object) but we
won‘t use it in this case.
We will use the same method as in the previous case to align points in inner part of
profile. Be careful to set inner points to axis of an object.
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If we have our curve selected in Object manager as active object
for editing, in Attributes Manager under Object tab you can see
its parameters. Here yo can change different curve properties and
also if curve is closed or not. (Close Spline). Deselect the box. Curve
will be now open between the first and the last point. (Yellow and
Red dots).
If those points are not in the rotation axis, select those points and
in context menu called with right-click are tool which we can use.
These are Set First Point, Reverse Sequence, Move Up / Down
Sequence
Move curve to have its open ends on rotation axis in the beginning
of coordinate system (0,0,0).
Curve is now ready to be rotated
Insert NURBS Lathe to the scene form top menu
Objects > NURBS > NURBS Lathe or use icon from palette
In object manager move curve under Lathe function. Next to
cursor is an arrow, which changes when we drag an object over
LATHE icon from horizontal to vertical. That shows, if we drop
Curve object now, it gets into Lathe hierarchically as a child.
We got rotational object.
Center of rotation is defined by lathe
axis and can be changed by moving this
axis (in mode AXIS TOOL) with MOVE
tool. Also the shape of rotational object can be changed by
moving of Spline object (in mode Model EDIT)
Model Tool - work with model
Axis Tool - work with model axis
In VIEWPORT settings we can switch to WIREFRAME mode and
see wireframe model, created with LATHE. Green checkmark
will turn on and off rotation function.
In Attributes Change curve type to B-SPLINE and try how
it works and how the curve and the whole lathe object is
affected. Try all types of curves and notice differences between
them. Return curve to previous mode.
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Insert HyperNURBS from menu Object from the main TOOLBAR
Move the whole Lathe group with Curve under HyperNURBS in Object manager. New
object is created and it is quite similar to B-Spline rotation. Only difference is in curve
connection in the axis of rotation. That is affected by HyperNURBS. Click on green
checkmark for HyperNURBS and disable it for now. Green checkmark turns to red
crossmark.
Let’s edit parameters of Lathe. In Object manager
select this function and in Attributes manager tab with
parameters is shown.
This function has to main tabs Object and Caps.
It tab OBJECT we can edit
Isoparm Subdivision - number of isoparm for viewing,
Angle - through which the spline is to be rotated.
Subdivision -Defines the number of subdivisions along
the rotation.
Movement - Movement is the longitudinal distance from
the beginning of the lathe to the end. If you set Movement
to 0, the spline rotates on a circle.
Scaling- Scaling determines the final scale of the spline.
Flip normals -Flips (reverses the direction of) the normals of the Lathe NURBS.
(Visible after object is converted to editable). Caps options are not important for this
case.
We will finish model of the first glass. In lathe parameters select subdivision to 48 and
this will create smooth surface on our object with edges where points are on a linear
curve. We can edit it a little .
Right-click or from menu structure call menu with tools and select Knife, which can
cut curve and add this way control points. Before edits change curve to linear mode.
Check if Knife tool has option line (line cut). Knife works this way: left-click to start
cut (outside of curve), hold LMB and move line to the end point of cut, release LMB
Add points to the curve accordingly to picture on next page. Points at the edge of
glass will make fillet cleaner and points at the rotation
axis will eliminate sharp point which occurs during
rotation. We have first model with circular shape.
Our goal is to create a few glasses with different shape
which will be always defined with our curve.
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So, make two more copies. Select Lathe group with Curve in
Object manager, and with CTRL key pressed down drag and drop
them in Object manager until cursor gets + sign. When dropped
copy is created.
Change position of new LATHE object in the scene with MOVE tool.
With visibility dots make original group invisible.
Switch to our newly created copy in Object manager and change
Subdivision to 8. Now we created polygonal model of Whiskey
glass with simple change of segments.
Switch viewport to perspective window and visually check position of both glasses.
(For change of position it is necessary to use)
New glass with polygonal shape is nice but to make
it realistic it needs fillets on the top edges. We will
fix this with HyperNURBS function. Copy again
model of this glass and set it to the middle of the
scene (coordinates 0,0,0) .Hide other glasses.
Select new model of glass and convert it to editable.
New object is now not controlled by curve. It turned to polygon mesh. Delete content
of previous HYPERNURBS which and move our polygon object there instead.
Turn this group on. Select active tool to Edge edit mode and select all vertical edges
on both, inside and outside polygons of glass.
How to select edges for editing
Select with LMB and add more elements to selection with SHIFT key. Add desired
vertical edges, and also rim edges on the top of this glass. For easier work
temporarily disable HYPERNURBS function either with checkmark or with Q-key.
If you select more elements than needed you can subtract them from selection with
LMB while holding CTRL key.
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Turn on HyperNURBS, use select tool and click on Active Tool tab, where we will set
roundness of edges.
Roundness of edges we will set with
HyperNURBS Weight window.
Set value to 85 % and confirm with button
Set. With this method we have very similar
glass to our previous lathe model but edges
are nice and smooth. This new glass is much
more realistic. We can select bottom rim
edges and set their weight to 75% too. Move
our last glass to different position and turn on
visibility for all glasses to compare them.
5.5 NURBS TOOLS USE
We have just explained practical use of Tool Lathe to create
rotation objects. Now we will discover some other tools for
NURBS modeling. All NURBS tools are accessible form MENU
OBJECTS or with icons from TOOLBAR
Extrude NURBS
The Extrude NURBS object extrudes a spline
to create an object with depth. The extruded
object appears as soon as you drop the spline
into the Extrude NURBS in the Object manager.
You can also use splines to cut out holes.
If, for example, a single spline object has two
segments (an outer circle and an inner circle),
the inner circle will be interpreted as a hole.
CINEMA 4D detects hole splines automatically.
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• All segments must be contained within a single spline object — additional splines
will be ignored. To connect the splines, select them and choose Functions > Connect.
Attribute manager
Movement
Into these three input boxes, enter the
extrusion distance along the X, Y and Z-axes
(based on the local axis system of the NURBS
object).
Subdivision
Defines the number of subdivisions along the
extrusion axis..
Iso Subdivision
Defines the number of isoparms used to display the Extrude NURBS when the isoparm
display mode is active.
Flip Normals
Flips the direction of the normals of the Extrude NURBS. Usually normals are in the
correct direction. However, with open contours it is not possible to know which way
they should point. In this case, you can control the direction of the normals, either
by changing the direction of the spline or by enabling the Flip Normals option. This
option does not effect the caps, since their normals are always calculated correctly.
Hiearchical
If this option is enabled, you can group, say, several splines within a Null object and
place this group in an Extrude NURBS. Each spline of this group is now extruded
separately. This is important especially for a text spline when you have enabled its
Separate Letters option. In this case, a separate spline is created for each letter;
these splines are in an object group. The Hierarchical option must be enabled to
extrude these separate letters.
Untriangulate
This option removes polygon edges where possible by converting triangles to
quadrangles. If the spline intersects itself that does not take the option into account.
Caps
Use these settings to add caps and/or rounding to the Extrude NURBS. The Caps and
Rounding settings are described later in this chapter.
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LOFT
The Loft NURBS stretches a skin over two or
more splines (although see the tip below). The order
of the splines in the Loft NURBS determines the
sequence in which they are connected.
If you want to create loft on only one curve (flat
text) Spline should be closed. Loft can be used for
combination of closed and opened splines too.
Original Splines. Creation of Loft surface.
• You can use a single spline with a Loft NURBS to
create a surface.
Attribute manager
Mesh Subdivision U/V
This gives the number of subdivisions in the U
direction, i.e. along the circumference of the crosssection.
Isoparm Segmentation
Defines the number of isoparms used to display the Loft NURBS when the isoparm
display mode is active.
Organic Form
If this option is disabled, the Loft NURBS lines pass
directly though the spline points and the distances
between the lines adapt to the spline points. If the
option is enabled, the Loft NURBS lines maintain
equal parametric distance to each other, creating a
looser, more organic form.
Loop
If this option is enabled, the first spline is connected
to the last spline in the V direction.
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CINEMA 4D
SWEEP NURBS
The Sweep NURBS requires two or three splines.
The first spline, the contour spline, defines the cross
section and is swept along the second spline, the path,
to create the object. The optional third spline (rail
spline) can be used to modify the scale of the contour
spline over the object’s length.
• The contour spline should lie on the local XY plane..
• You can use splines with multiple segments, e.g. you can sweep an entire word
along the path.
The contour spline is swept along the path in the direction of the contour’s Zaxis. If you are using a planar (two-dimensional) path spline, there are no further
considerations.
However, the behavior of the sweep is a little more complicated with a non-planar
(three-dimensional) path. If you enable Banking, the following rules apply: The
contour spline is rotated at the start of the path spline so that its X-axis is parallel to
the average plane of the path spline.
This plane can be used to control sweep but loop option can not be used at the same
time. In this case is appropriate third spline to control direction and size of profile for
the whole sweep.
Banking allows you to use arbitrary 3D paths. However, it is not suitable for a precise
sweep since the contours may break up, depending on the path. If the Banking option
is disabled, the following applies: the contour spline is rotated for each subdivision
so that on the one hand its Z-axis is always tangential to the path spline and on the
other hand its X-axis is parallel to the XZ plane of the path spline. You can use this XZ
plane to control the sweep, although you do lose the ability to model loops, since the
contour flips over when the path runs vertically.
Finally, there is another, much more powerful functionality — you can use a rail spline
to control the direction and/or scale of the contour as it runs along the path. The path
spline controls the positioning of the subdivisions. Adaptive spline interpolation is
usually a good choice since it generates a relatively low number of surfaces. Uniform
spline interpolation, on the other hand, is the better choice for animation since the
subdivisions will be a uniform distance apart.
A common mistake when using rail splines is to use a path spline with adaptive
interpolation. This can generate insufficient subdivision for the rail to work properly
— a higher resolution is required. You can solve the problem by setting the path’s
Intermediate Points to Natural.
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CINEMA 4D
Figure shows - ADAPTIVE INTERPOLATION and
NATURAL INTERPOLATION and final object.
Control splines are on the right side
Attribute manager - Object properties
Isoparm subdivision
Defines the number of isoparms used to display the
Sweep NURBS when the isoparm display mode is
active.
Scaling
Determines the size of the contour at the end of the
path. The contour is 100% at the start of the path
and the size is interpolated in between.
Rotation
Defines the rotation about the Z-axis that the
contour has passed through by the time it reaches
the end of the path.
Growth
Defines the size of the sweep. 50% means the
contour spline is swept along the half of the path. If
the path is closed, you can set caps (but not rounding) when the growth is less than
100%.
• You can animate the growth by recording the Growth parameter. For example,
you can gradually write a word by using a circle spline as the contour and a spline in
the shape of the handwriting as the path.
Parallel movement
If this option is enabled, the contour is swept in a parallel manner (i.e. it is not
rotated at all).
Banking
If Banking is enabled, the contour spline will lean into the curves of the path spline.
The initial banking angle is set to the average plane of the path spline, which is
calculated from the position of the path’s spline points. The banking angle must be
chosen at random for straight lines since they cannot define a plane. In this case, turn
off banking to make the contour will run parallel to the path spline’s XZ plane.
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Use Rail direction
Enabled (left) and disabled (right), If enabled the rail spline will influence the rotation
of the contour about its Z-axis.
CAPS
Parameters are the same for Sweep, Extrude, Lathe and
Loft NURBS
Start/ End
Use the Caps and Rounding page to
change the rounding at the start and
end of the NURBS object. Parameters
Step and Radius have separate
settings for each cap.
Fillet, Cap or both are common parameters.
Steps - Here you enter the number of subdivisions for the
rounding at the start of the object.
Radius - Determines the radius of the
rounding at the start of the object.
Fillet type
Choose the shape of the rounding
from this drop-down list. When the
constrained mode is active, all fillet
types except the Engraved type
extend the length of the extrusion of
the NURBS object.
Different materials for the hull, caps and rounding
You can apply different materials to the hull, caps and
rounding. To do this, either convert the object into polygons
For example, using the Extrude NURBS you can create edges
with different material then the rest of cylinder created with
NURBS tool.
Restricting a material to an invisible selection — in this case,
the rounding at the front of the text.
Apply a material to the start cap by using the
Selection box (Texture tag). For example:
C1 = Cap 1, C2 = Cap 2, R1 = Rounding 1,
R2 = Rounding 2.
Or you can drag materials on polygons
manualy.
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5.6 MODELING TOOLS
Modeling tools are also another method which gives us further
possibilities how to model out project. Some of them we will
discuss in this chapter. You can find them in the menu Objects
> Modeling or through Toolbar Icons
BOOLE - Boolean operations
It performs realtime Boolean operations on primitives or
polygons. This means that you can see the result in the viewport
as soon as you make the two objects children of the Boole
object (try two spheres for testing). The default Boolean mode is A subtract B.
• The Boole object also works with hierarchies. This means you
can cut not only one but two or more holes in an object using
A subtract B. Each further cut object must to be located in a
hierarchy under the first cut object.
• For a cleaner cut (i.e. if you can see defects), increase
the number of subdivisions for the objects.
• Most of these settings are available in High Quality mode
only.
Boolean Type
Four Boolean modes are available:
A + B
A - B
A intersects B
B minus A.
A Union B: Object A is merged with object B.
A Subtract B: Object B is subtracted from object A.
A Intersect B: The volume of intersection is shown.
A Without B: This is similar to A subtract B, but it is not a genuine Boolean
operation. It cuts holes in object A without capping the holes.
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High quality
The Boole object incorporates a high quality Boolean algorithm known as Better
Boole. Enable the High Quality option to use the Better Boole algorithm, which
generates a cleaner mesh with fewer polygons (triangles).
Create single object
If you convert the Boole object to polygons (Functions > Current state to object
or Make Editable) and this option is enabled a single object is created. If the option
is disabled, the Boole object’s Phong tag will be evaluated if present.
Optimize
This parameter is only available if Create Single Object is enabled. If the Boole object
is converted to polygons, points within a set distance of each other are merged to a
single point. Enter the desired distance into the
box. In the example, the Boole has been applied
to the top-right and bottom-right objects. The
following settings were used.
Left: Create Single Object disabled.
Center: Create Single Object enabled.
Right: Create Single Object and Create Phong
Breaks At Intersections enabled.
Instance
To create an instance of an object, select the object in the Object manager
that you want to instance and choose Objects > Modeling>Instance.
The instance now appears in the Object manager.
To change which object is referenced, first select the Instance object in the Object
manager to display its settings in the Attribute manager. On the Attribute manager’s
Object page, you’ll find a box called Reference Object. Drag and drop the name of
the object that you want to be instanced from the Object manager into the Reference
Object box.
Attribute manager
To reach these commands, click the triangle next to the Reference Object box.
Clear
Removes the reference to the original object.
Show in manager
Scrolls the Object manager if necessary to make the original object visible..
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CINEMA 4D
Selected Element
An instance object is a special duplicate of an object that does not have its own
geometry. As a result, instances require far less memory than conventional
duplicates, but the advantages do not end there. Imagine that you have created a
street scene with over 40 street lamps (all instances of the same original object). By
adjusting the brightness of the original lamp’s light, you can change the brightness of
all lamps in one go. You may even edit the original with the modeling tools and the
instances will follow suit. Material properties are adopted as well. Only the position,
scale and rotation are independent of the original.
An instance object will not significantly increase the size of the saved CINEMA 4D file.
However, the CINEMA 4D editor will still need to allocate additional memory as if the
instance object were a non-instance duplicate. The Scene Information dialog shows
instance objects to consume as much memory as duplicates.
SYMMETRY
• The Symmetry object works with geometry and splines only, not with lights,
cameras and so on.
The Symmetry object is especially useful when polygon modeling symmetrical (or
nearly symmetrical) objects such as faces. Model just one half of the object and the
other half is generated automatically. Once you’ve finished modeling one side you
might want to make the Symmetry object editable to convert the generated half
into polygons. You can then tweak either side separately to avoid the model looking
unnaturally symmetrical.
Try something simple: create a sphere, convert it to polygons with Functions >
Make Editable and select the Points tool. Select the Rectangle Selection tool and, in
the Front view, select the right half of the Sphere object’s points and delete them.
Create a Symmetry object and, in the Object manager, make the sphere a child of the
Symmetry object.
The right half of the sphere is generated and the sphere is complete once more.
Note that only the left-hand side has points. Now edit some of the points on the lefthand side, perhaps with the Magnet tool. Notice how the generated side is updated
automatically.
Mirror plane
Determines which plane is used as the mirror. ZY is the default since it is used in the
front view for objects with vertical symmetry, such as a face.
Weld points
If the Weld Points option is enabled, points at the mirror’s edge are welded
automatically — two points become one.
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Transcription

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