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这里有一堆的点，你在它们周围画一条绷紧的线。你可以阅读中关于凸包的部分，将会注意到可夫斯基求和（Minkowski Summations）和这样的方程式：∑&Sn = { ∑&xn : xn∈&Sn }。
关于凹包则是紧裹在数据集范围上的一个面，就像长跑运动员的运动衫一样，你会感觉生成这样的面特别困难，对不对？有一个叫做的网站，给出了如下的例子：
其实一旦你理解了alpha值，使用FME来生成凹包就不再困难。这个参数甚至还能处理那些错误的点并且保证结果是正确的！让我来展示给你看如何做……
Alpha Values（Alpha值）
Alpha值的范围（理论上）从0到无限大。
当值为无限大的时候你得到的会是一个非常标准的凸包。因此，值越大，在点周围的包面将更加类似于上图所示的橡皮筋。
但是当值为0时你得到的结果则相反。包面被压缩了太多以至于不再存在；有点像我们运动员的衬衫变得非常紧，看起来像画上去的那样。
我原本打算插入运动员的图像来阐明这些点。但是搜索“body paint”后返回的图像明显不适合！只能对上面的点数据进行想象——每个点有他们自己的无限小的包面。
我们来看一个例子，我们将很快看到为什么会发生这样的情况。
Example（例子）
这里我使用一个标准的城市公园的数据（city park），这个数据我们在很多培训中用到过：
在所有要素周围的凸包看起来像这样（使用HullAccumulator生成的）：
像我说过的那样，当我创建凹包并把alpha参数设置为一个很大的值，如9999999时，得到的结果与凸包一样，你不必为此感到惊讶。这里不需要截图来说明-与上述相同。
接着，当我减少alpha value的值（减到8500），我开始得到一个更加紧贴的轮廓：
减到6500时，轮廓依然紧贴：
因此要想找到一个理想的alpha值，我推荐的方法是你从一个较大的值开始，然后减少该值知道生成的凹包满足你的需求为止。
因此要想找到一个理想的alpha值，我推荐的方法是你从一个较大的值开始，然后减少该值知道生成的凹包满足你的需求为止。
数值的含义是什么？
这是一个非常好的提问。你需要了解这个问题，因为你将发现，有用值的范围会根据坐标系的单位而发生变化。因此虽然的范围适合于上面的’State Plane’的数据，但在我使用经纬度数据（Lat/Long）做测试时，0.5到0.3更合适。
关于该章节，我是真的非常感谢Alastair Aitchison（他偶尔还使用FME到）写的这篇以及Safe公司核心团队的专家们。
基本上凹包的过程是先将数据转变为Delaunay三角网，如下：
然后应用alpha值。外接圆半径大于alpha值的三角形将被丢弃。剩余的所有（如外接圆半径小于alpha的三角形）将融合到一起，形成一个包面。
本质上，三角形大于alpha值的将被丢弃，剩余的融合到一起。这个截图显示了当alpha为6500时，哪些三角形被删除以及哪些被留下：
现在你可以理解为什么一个大的alpha值会生成一个更凸的边界-因为较少的三角形被丢弃并且添加了很多三角形到整个形状上。当你的alpha大于最大的外接圆半径时，将不会丢弃任何三角形。
相反的，越小的alpha将产生更凹的边界，因为这样会丢弃更多的三角形。当然如果你的alpha值小于最小的外接圆半径时，你丢弃了所有的三角形以至于没有结果生成：这种情况下，FME将输出非几何要素：
这导致了两个重要的点。首先，当数据规则分布时，将得到更好的“凹性”，因为最大的三角形将出现在三角网模型的边缘并且将第一个被丢弃。当数据不是均匀分布时，最大三角形将在三角网模型中，产生一个难看的包的形状。我们将在下面看到。
其次，你会注意到，外接圆半径的大小/单位是与数据的大小/单位紧密相连的，因此alpha的值将根据使用的坐标系发生较大的变化。
顺便如果你不知道什么是外接圆半径，不用担心。它很简单。它就是最小边界圆的半径，最小边界圆是包含指定三角形的三个顶点的圆。
例如，这个三角形被一个圆包围。实际上它是最小的能内切三角形的圆。这就是外接圆，外接圆的半径（红色线所示）就是外接圆半径：
因此我们在三角网中计算每个三角形的外接圆半径，当它大于alpha值时，它所属的三角形将被移除。剩下的三角形融合到一起形成凹包。
So Bad That It’s Good!
好了，你可以想象不必真的将alpha值减少太多，因为这样可能导致在移除三角形后，产生奇怪的形状。&
例如，如果我将公园的alpha值减到6000，将会丢失一个特殊三角形，导致一个难看的岛洞：
在上面三角网的截图中，你可以明显看到哪个三角形达到了alpha的极限并被删除。这里主要是由于数据错误：数据分布不够均匀。我提到过这样会导致较大的内部三角形生成洞——就像上面的那样。&
当然，如果我将alpha降低更多，我会得到更多更奇怪的形状。我甚至可以得到在特殊条带中被移除三角形的所有顶点，像下面高亮显示的那样：&
……这样会产生两个独立的包面，两个包面间有较大的缝隙。
另外，如果在转换器中将alpha参数保留为空值，FME会计算一个最小的alpha值，根据这个alpha值会创建唯一的多边形要素；因此当你为选择自动方法感到高兴时，还不用担心会生成有缝隙的面。
因此我可以做的是减小alpha值故意生成缝,隙，但是确定这样就不好吗?或者好呢？让我试试alpha值为3500的情况：
这个值不是特别有用，它的轮廓看起来像一只狮子狗。接着尝试alpha值等于1500：
哇哦！现在移除了很多三角形，输出的结果已经不再“坏”而且看起来比较有用。
那么现在我们可以有一个很好的方式对一组要素创建包面/轮廓，而且不需要使用相同的属性进行分组！我将它看作一个概括数据的好方法。
实际上我也是上周做支持时，我的同事Dmitri建议我如此尝试一下时，学习到的这个方法。一个用户有一个点云数据集，但是数据中有不同的点云集，像是一系列的迷你云。我认为每组是一个独立的建筑。用户的需求是对每组迷你点云创建一个外轮廓，这个方法很好的做到了这点。
作为概括来说，上述的“公园区域”的数据没有看起来比你期望的更弯曲吗？像这样：
我使用最近从Dale Lutz那里学到的方法：Generalizer转换器中的NURBfit算法。我不知道什么时候开始在Generalizer转换器中增加了这个特殊的算法，但是我发现将尖锐的边界变成柔和曲线时它非常有用。
显而易见，概括后的数据使得它看起来不再像之前那样精确。但是在很多情况下——尤其是本身的包面就不十分精确的情况下——这并不是一个严重的问题。
你不得不承认它看起来更好了。
嗯~我好像把一个参数作为这篇文章的主要部分了。但是我很高兴的是，学到的关于凹包的这些知识，我一定会在我的FME中保留这些技术。
为什么不启动Workbench然后自己试试呢？
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官方公共微信怎么用BodyPaint 3D绘制贴图_百度知道Fill and Stroke Paint
There are a number of different options for the Fill
and Stroke paint of an object.
Examples of the different options are shown below.
The use of these options for the Fill and the
Stroke paint is basically the same, so we'll use
the word fill to talk about both
at the same time.
The fill type can be set using the
(Object →
Fill and Stroke...
(Shift+Ctrl+F) or click on
the Fill and Stroke paint tabs. The fill type can be
one of the following choices (set by clicking an icon):
No paint (transparent).
Flat (solid) color.
(a smooth transition between two or more colors).
(a smooth transition between two or more colors in a radial direction).
(filled with a repeating pattern).
(document dependent swatch). New in v0.48.
Unset (necessary for giving different attributes to cloned copies of an object).
A Gradient fill type can also be selected by using the .
Each of the options
(except the No paint and
Unset options) is discussed below.
Flat (Solid) Colors
Color can be the simplest or the most complicated aspect of a
drawing depending on your needs. Color is stored internally in
Inkscape as a six-digit
number consisting of
three pairs of digits. Each pair of digits corresponds to the
amount of Red, Green, Blue (). This matches the
specification for describing color. For example, a color defined
as #FF7F00 has red, blue, and green components of 100%,
50%, and 0%, respectively,
of the maximum values.
In some cases, a fourth pair of digits is added to describe
(). The A or
attribute may not be familiar to many
people. This attribute specifies how transparent the fill should
be. It can range from 0 for complete
( FF) for complete . The term opacity
is often used in place of Alpha. Its value ranges from 0% (0.0)
for a transparent object to 100% (1.0) for an opaque object.
In principle, this is a simple description for
specifying any color. The complexity comes from assuring that the
color reproduced on a display or in printing matches the color the
artist envisioned. Various color “systems” have been
developed to facilitate this. Inkscape supports
functionality through the use
Setting up color management can be done under the Color
management section in the
You can declare multiple ICC profiles for a document
in the Color Management tab of the
Document Properties dialog.
If everything is setup properly the
“Color Managed View” can be toggled on/off via
View →
Color-managed View
or by clicking on the
icon in the lower right corner of the
window. This will give a better
representation of what you can expect to see in the final
rendering of the drawing as well as mark out-of-gamut colors.
Note, profiles internal to a
are not used.
A complete discussion of this topic is beyond the scope of this
The fill color of an object can be modified a variety of ways, including
dialog, and
Some of these methods can also be used to change the color of a Gradient stop
when a Gradient handle is selected.
Fill and Stroke Dialog—Color
When the use of a flat (or solid) color is specified for the
Fill and Stroke paint of an object, the corresponding
tab of the
dialog will show five sub-tabs, each
one corresponding to a different method of specifying the color
plus one for color management.
Each method is described next in its own section.
Except for the Wheel tab, each color
parameter can be set by either dragging a slider (small
triangles), typing the desired value into the entry box, using
the up/down arrows in the widget
(Right Mouse Click on
an arrow causes the value to change to the minimum or maximum,
Middle Mouse Click cause
the value to increment or decrement by 10),
Up/Down Arrow
keys after the entry box is selected. The slider bar shows the
current value (triangles) and what the color will look like as
that slider is dragged.
specifies how transparent the fill should be, 0 for
completely transparent and 255 (100) for completely opaque in the
case of the , , and
(Red, Green, Blue) is a method for specifying a
color in terms of the three additive primary colors. This is the native
method for computer screens.
Range of allowed values is from 0 to 255 (0 to FF in ).
Saturation,
Lightness) is
a method for specifying color in terms of hue (color in optical
spectrum), saturation (intensity-purity), and lightness. The
range for saturation is from a pure color to gray. The range for
lightness is from black to pure color to white.
allowed values is from 0 to 255 (0 to FF in ).
(Cyan, Magenta, Yellow, Key [Black]), is
a method for specifying color in terms of subtractive
primary colors and is commonly used in printing.
Range of allowed values is from 0 to 100.
Inkscape stores color internally in the
format. This is
the only color specification supported by . Furthermore,
the entry boxes are set up so that the value in one is always
zero. (Any color in RGB color space can be defined using only
three of the CMYK terms. The definition is not unique.) Better
support for CMYK is planned.
The Wheel is an alternative way of changing
color in the
paradigm. Dragging the line around the circle
changes the Hue. Dragging the small circle
within the triangle parallel to the edge that varies from white
to black changes the Lightness and dragging
perpendicular to that edge changes the
Saturation.
This tab allows editing of colors managed by an icc
profile if enabled.
Palette and Swatches Dialog
The color , located near the bottom of the main
Inkscape window, and the Swatches dialog
(View →
Swatches...
(Shift+Ctrl+W)) allows one to quickly set the color of an
object's Fill or Stroke or to set the color of a
. They can also be used to set the
. Their use is essentially identical so they will
be treated together. The visibility of the Palette can be
toggled via a check box in the View →
Show/Hide submenu.
The following methods are available for both the Palette and the
Swatches dialog:
Left Mouse Click on a swatch to change the
Fill of selected objects or the color of selected
Gradient Stops to the color of the swatch.
Shift+Left Mouse
Click on a swatch to change the
Stroke of selected objects.
The Current style will also change (no object need be
selected).
Note, the Current style is not displayed correctly
in v0.48 if the Auto palette is
Left Mouse Drag from a swatch to an object's
Fill or Stroke or to a Gradient Stop to
change the corresponding attribute to the swatch's color.
Shift+Left Mouse
Drag to anywhere on an object to
set the Stroke color (except to a GradientStop).
The target object need not be selected. The Current style will
not change.
Left Mouse Drag from a swatch to the Fill
or Stroke part of the
to change the
Fill or Stroke of selected objects. The Current style
will also change.
Right Mouse Click on a swatch to open a small
dialog which allows you to assign the color to the Fill or
Stroke of selected objects. The Current style will also
In v0.48, one can also edit or delete a
this dialog.
You can also drag colors to or from other applications that
support Drag and Drop.
Inkscape has a variety of built-in palettes (some
copied from Gimp).
More palettes can be added by installing palette
files in the directory share/palettes. The
files use the Gimp palette file structure where colors are
defined in terms of a triplet of numbers in a
format. See
in , for details.
Auto PaletteNew in v0.48.
An Auto palette was added in v0.48. This is the
default palette shown in the Swatches dialog. Initially it is
empty. It will automatically include
as they are
added to a document. This palette is document dependent.
Both the Palette and the Swatches dialog have a
pull-down menu (far right, small arrow) where you can set the size and shape
of the swatches, if the colors should be displayed in one row or
in multiple rows, and which palette should be used. Hovering the
pointer over a swatch will display a color's name in a
and in the .
A scroll bar gives access to colors in a palette
that are not displayed when there are too many colors to fit.
Style Indicator
located on the left side of the
displays information on selected objects, text
fragments, or Gradient stops. The indicator includes a
number of methods to alter style, including: pop-up menus, targets
for Drag and Drop colors, and
has three parts showing ,
(O), which show attributes for
selected objects or text fragments.
parts are referred to as the
fill indicators.
A displayed fill attribute can be one of:
Color swatch: Shows color with (left) and without (right)
(Alpha refers to the Fill and
Stroke paint attributes and not the object's
N/A: Not Applicable (i.e., no object selected).
None: No fill defined.
Unset: fill is unset.
L: fill is a linear Gradient.
R: fill is a radial Gradient.
Pattern: fill is a pattern.
Different: More than one object selected with different fill.
When multiple objects are selected and all of the selected objects have
a color fill, then one of the following letters will be shown:
m: Selected objects have same fill color.
a: Selected objects have different fill
colors. The color displayed is an average of the colors in
the selected objects.
For Gradient handles, both parts ( and )
show the handle color.
has a number of features that depend
on the part.
Fill/Stroke Paint indicators:
A Left Mouse Click opens
dialog with the corresponding tab
A Middle Mouse Click on a bar removes the
fill from the selected objects if a fill is defined. If no
fill is defined, it sets the fill to black.
A Right Mouse Click on a bar opens a pop-up
menu as discussed below.
A color from the
dialog can be
dragged and dropped onto one of the fill
indicators to change the fill of all selected
Stroke indicator:
A Left Mouse Click
dialog to the Stroke style tab.
A Right Mouse Click
opens a pop-up menu that allows the stroke width unit to be changed
as well as a preset width to be selected. The stroke can also be removed
with this menu.
Opacity indicator:
A Right Mouse Click on the numeric field
opens up a pop-up menu with preset opacity values.
A Middle Mouse Click on the "O:" label cycles
through the opacity values 0%, 50%, and 100% (0.0, 0.5, and 1.0).
Fill Indicator Pop-up Menu
A Right Mouse Click on either the
bar opens a pop-up menu with entries that act
on the Fill or Stroke paint of the selected objects or
text fragments, depending on which bar was clicked. If a Gradient
handle is selected, the menu entries apply to that handle.
Edit fill... (Edit stroke...):
dialog. (The dialog can also be opened
directly by a Left Mouse Click on the
part of the .)
Last set color: Applies the last set color to the
of selected objects.
A color is set when a color is applied to any object or when a color is selected
from the .
Last selected color: Applies the last selected color to selected objects.
The last selected color is the color of the previously selected object(s) prior to selecting
the object(s) whose color is to be changed. If the color is to be applied to multiple objects,
they must be selected together using a
selection.
are ignored in determining last selected color.
Invert: Inverts the color of the
of selected objects. If more than
one object is selected, the colors of those objects are averaged before the color is inverted.
is not changed.
White: Set
Black: Set
Copy color: Copies color of selected objects to the clipboard in
If more than one object is selected, the colors of those objects are averaged.
Paste color: Pastes color to selected objects from the clipboard.
Swap fill and stroke: Exchanges Fill and Stroke paint colors.
Make fill (stroke) opaque: Sets
to full . (Does not
Unset fill (stroke): Unsets the
of selected objects.
Remove fill (stroke): Removes the
of selected objects.
Color Gestures
Color Gestures is the name given to changing
the color of a Fill, Stroke, or Gradient Stop
by dragging the mouse from a fill indicator into the Inkscape
The principle is that as you drag the mouse, the color
will change proportionally to the distance from a 45° line
from the indicator. The farther away you are, the more subtle
the changes can be. Changes are made in the
color space.
Without any modifier key, changes are made to hue. With the
Shift changes are made to saturation while with
the Ctrl changes are made to lightness. Note
that the letter next to the cursor will change to indicate the mode.
modifiers can be changed while dragging. When a key modifier is
changed, the “zero” line (normally at 45°)
changes to pass through the current cursor position. This is to
avoid abrupt changes in color when changing modifiers.
The Alt modifier disables changes to the color
so that the cursor can be repositioned.
If more than one object or Gradient Stop is selected,
the starting color will be the average color of the selected
items and the final color will be the same. If you wish to shift
the color in the same way for a number of objects but preserve
the relative differences use the .
Color gestures are very useful once you get the hang of them. It
is well worth spending a little time to play with them!
Dropper Tool
The Fill and Stroke paint color of an object can be
changed by using the Dropper Tool to grab an existing color
in the drawing.
Options allow for grabbing the average color over a circular region,
inverting the grabbed color, and saving the grabbed color to the
hexadecimal number).
To use the Dropper Tool, first
select the object that you want to modify with a tool
other than the Dropper Tool.
Recall that you can switch temporarily to the
by using the Space Bar.
Then select the Dropper Tool by clicking on the
icon (F7 or
D) in the .
Finally click with the
Dropper Tool on the desired color. The shortcut
D will toggle between the Dropper Tool
and any other tool.
The Shift causes the chosen color to be applied to
the object's Stroke paint rather than the Fill.
The Alt causes the inverse color to be applied.
The Shift and Alt keys can be used in combination.
However, neither of the modifier keys are useful when copying a
color to the clipboard.
Left Mouse Click:
Pick Fill color.
Left Mouse Drag:
Pick average Fill color (color is averaged over circle created during drag).
Copy color under cursor to system clipboard in the form of an 8-digit
hexadecimal number (2 digits for each of ).
The Dropper Tool
has two buttons that
determine if the
() of a color should be
Picked and/or
Assigned. These settings affect the way a color is
picked if the “Picked” object has an
different from 100% (or 1.0).
Pick opacity disabled:
The color picked is as shown on the screen. For example,
picking the color from an object with a dark blue fill but an
opacity of 50% would result in a light blue color with an
opacity of 100%. Opacity of set object not changed.
Pick opacity enabled, Assign alpha disabled:
The color picked is the color that the object would have if
its opacity was 100%. A dark blue object with an opacity of 50%
would result in a dark blue color (an opacity of 100%).
Opacity of set object not changed.
Pick opacity enabled, Assign opacity enabled:
The color and opacity are both copied from the picked
object. A dark blue object with an opacity of 50% would result
in a light blue color composed of a dark blue fill with an
opacity of 50%. Opacity of set object changed. Note: This is
only applicable if the color is picked from an object with
that is not over another object.
Gradients are a smooth blending from one color to
another. Gradients can be used to build up complex shading
of an object as shown in the flower petal below. Note:
Inkscape supports the
filter, which may be
an easier way to produce complex shadings.
In Inkscape, Gradients can be linear
or radial and can consist of transitions
between two or more well-defined colors referred to as
Inkscape does not support nonlinear Gradients. Nonlinear Gradients
can be simulated by adding extra Stops.
There are three parts to using a Gradient; each treated in the next three sections:
Attach a Gradient to an object.
Edit the Stops.
Adjust the orientation and extent of the Gradient.
The use of linear and radial Gradients
is essentially the same and both will be treated together.
If you want a Gradient to transform with an object, you must
toggle on this option using the
that is in the
is in use.
Attaching Gradients to Objects
Gradients can be attached to an object either with the
Fill and Stroke dialog or through
the use of the Gradient Tool.
To attach a Gradient with the
dialog, simply
select an object and click on either the linear
or radial Gradient
in the dialog. A Gradient with two Stops will automatically
be created and applied to the object.
The Stops will have the
color of the previous
with one Stop having full
and the other full .
The following figure shows the dialog after attaching a Gradient
An already defined Gradient can be assigned to the object
by selecting the Gradient from the drop-down menu under
the Fill tab of the
dialog. A Gradient can also be assigned to the
an object under the Stroke paint tab.
To attach a Gradient with the Gradient Tool, select
the tool by clicking on the
(Ctrl+F1 or g) in the .
The Gradient Tool
has options to choose a linear
or a radial
Gradient and the application of the Gradient to the
of an object. Once the options are selected, Left Mouse
Drag across an object to attach a Gradient. The
start and stop point of the drag will define the range of the
Gradient (where the start and end Stops are placed,
see below).
If an already defined Gradient has been chosen from the
drop-down menu in the
it will be applied to the
object. Otherwise a two Stop Gradient will
automatically be created with both Stops the color of the
objects existing
and with one Stop full
and the other with full .
Editing Stops
Gradients can be modified by adding, deleting, moving, or
changing the color and
of Stops. They can be
edited onscreen. This is much more convenient than using the
Onscreen Editing
An object with a Gradient displays Gradient handles
when the Gradient Tool, , or one of the
is active (the latter two if enabled in the
dialog). Some editing actions work when
any of these tools is active, others work only with the
Gradient Tool.
Circle, diamond, and square handles
represent start, intermediate, and end Stops,
respectively. Editing Stops has many parallels to editing
Stops can be selected by clicking on them with the
Gradient Tool, the , or one of the
. To select more than one use
Shift+Left Mouse
Click. With the Gradient Tool you can
selection by
using Shift+Left Mouse Drag
or you can select all the Stops by using
To add a new intermediate Stop, with
the object selected and the Gradient Tool active:
Double-click on the Gradient path. A new Stop will
be added where you clicked. The Stop will take the
existing color under the path.
Ctrl+Alt+Left
Mouse Click on the Gradient. A new
Stop will be added where you clicked. The Stop will
take the existing color under the cursor.
Select two adjacent Stops and
press Insert. A new Stop will be added
halfway between the selected Stops and with a color
halfway in-between.
Drag a color from the
dialog unto
the Gradient path. A new Stop will be created with
the dragged color at the point of the drop (drop too far from
the path and the
will be changed to solid with the
dragged color). This also works if the
is active.
To remove an intermediate Stop, with
the Gradient Tool active:
Click on it using
Ctrl+Alt+Left
Mouse Click. This also works if the
or any of the
are active.
Use the Del to remove selected .
If there is at least one intermediate
Stop, then deleting
the start or
end Stops will shorten the
Gradient with the nearest
intermediate Stop becoming
a start or end
Stop. If there is no intermediate
Stop, then deleting a start
or end Stop will replace the
Gradient with a solid Fill of the color of the
remaining Stop.
Using Ctrl+L
will attempt to simplify the Gradient over the a region
defined by selected Stops by adjusting and removing some
Stops. This is particularly useful for removing redundant
To move an intermediate Stop:
Drag it with the Gradient Tool, , or one of the
. If more than one Stop is selected, they
will all move together. Dragging with
the Ctrl snaps the Stops at points that
are multiples of 1/10th of the distance between the nearest
neighboring unselected Stops. Dragging with
the Alt moves selected Stops according
to how far away they are from the dragged Stop.
With one or more Stops selected and the
Gradient Tool active, use the Arrow keys.
If multiple intermediate Stops are
selected, they will move together. Using
the Shift with the Arrow
keys accelerates the shift by a factor of 10. Using
the Alt moves the selected Stops one
screen pixel at a time. Using
moves the Stops 10 screen pixels at a time.
Note: You cannot move a Stop past an adjacent Stop.
There are several ways to see and change the style (color
and/or ) of one or more Stops. In
general, if no Stop is selected, indicators and changes
apply if one Stop is selected,
indicators and changes apply to that Stop; and if multiple
Stops are selected, indicators show an average value for
the selected Stops and changes apply to all selected
dialog: If no Stop is selected, the
Gradient is previewed at the top under the
Otherwise the current color and
values for selected Stops are shown. Changes apply
to all selected Stops.
The : If no Stop is selected the
indicators show previews of the Gradients ( and
). Otherwise the current values for selected
Stops are shown. Changes apply to all selected
Stops. See
, earlier in
this chapter for more details.
Drag-and-Drop: Colors can be dragged from either the
or from the
dialog onto Stops (or onto the
Gradient path to add a new Stop).
Copy-and-Paste: Colors can be copied to and from the
clipboard.
Copying to the clipboard (Edit →
will copy a Stop color and
if one Stop is
selected or the average color if more than one is
selected. Pasting the style (Edit →
Paste Style
(Shift+Ctrl+V)) copies
from the clipboard the color and opacity to all
selected Stops.
Using the Gradient Editor Dialog
There is a dedicated Gradient Editor dialog for editing
Gradients. It is envisioned that this dialog be removed
as redundant in the future. To call up the dialog, click on the
Edit... button, either in the
dialog or the -. Note that
which Gradient is being edited does not change automatically
when you select an object with a different Gradient.
In this dialog, the Gradient is shown at the very top. Next down
is the current . You can see that the
Stop shown above is a solid blue, fully opaque with
255. You can also see from the Offset
slider that the Stop shown is set all the way to the left (and
as the Stop is at one limit of the Gradient, its position can't
be moved). The color and transparency of this Stop can be
changed in the Stop Color section. The tabs
work the same as those described in the
section above.
can also be used to change
one of the end Gradient colors by first selecting the corresponding
Gradient handle.
(To modify a non-end Gradient color, copy the color to the
with the desired color selected with the Dropper Tool and then
paste into the Gradient Editor
entry box.)
To edit another Stop, select that Stop in the pull-down menu. In
the default case described above, the second Stop has
the same color as the first but is fully transparent (e.g.,
= 0). This is shown in the current
section by the divided box. The left
half shows the color with Alpha and the right half without
Alpha. Note also that the Offset slider is
fully to the right.
To add a Stop, click on the Add stop
button. The new Stop will be added to the right of whichever
Stop was selected, unless that Stop was the farthest to the
right, in which case the new Stop will be added to the left. The
position, color, and transparency for the new Stop will be set
to halfway between its neighbors.
The following figures show a third Stop added to a Gradient after
its color and position have been adjusted.
To delete a Stop, select the Stop, then click on the
Delete stop button. As at least two Stops
are required to define a Gradient, you cannot delete a Stop
via the dialog if only two are defined.
Adjusting Gradients
Once a Gradient has been applied to an object, the
orientation and extent of the Gradient can be changed via
dragging the outer two Gradient Stops indicated by
the square and circle handles. The handles appear when the
Gradient Tool is selected. They will also appear by default
when many of the other tools are selected (controlled by
the Enable Gradient editing option in
dialog under each tool tab).
linear Gradients, one set of handles define the range of
the Gradient. The Gradient is parallel to the line
connecting the two handles.
For radial Gradients, there
are two sets of handles (or Stops) at right angles to each
other, sharing the square center handle. The center, handle
controls the origin of the Gradient
(one “edge”), while the two circular handles
control the range of the Gradient in orthogonal
directions. This allows a radial Gradient to have an
elliptical shape.
A radial Gradient can be made asymmetric by dragging the center handle (diamond)
while holding down the Shift key. A cross will appear where
the center of the Gradient is located. The cross can be dragged to make further
adjustments.
Gradient handles from two different objects will snap
together if one is placed over the other. This facilitates
aligning Gradients between different objects. The handles
will then move together. If multiple objects are selected when a
Gradient is created, all the objects will share a common
An option only accessible through the Gradient tabs
of the Fill and Stroke dialog is defining how the
area outside the Gradient range is filled. The three options are:
fill with the solid color of the edge Stops (None),
fill with a reflection of the same Gradient (Reflect), and fill with a
translation of the same Gradient (Direct). The effect of these three options
is shown next.
keyboard shortcut
reverses the Gradient direction when the Gradient Tool
is active. This is especially useful for radial Gradients
where one cannot just drag the Gradient handles to reverse
the Gradient.
Any object or set of objects can be turned into a Pattern
and used in the fill of an object. The Pattern can be
shifted, rotated, and stretched as necessary. Inkscape
includes a set of Patterns accessible through the
dialog. The
tutorial covers creating and using
Check the licenses of the bitmap patterns included with
Inkscape to see if they are compatible with your artwork. They
are not public domain!
(Look inside the
file or use the
to look in the “defs” section.)
The Patterns included with Inkscape are defined in the file
patterns/patterns.svg located in the Inkscape
“share” directory. Edit or replace this file to include
your own stock Patterns.
To use a Pattern, two or three steps are necessary. The
first, optional step, is to create a Pattern. The second is
to apply the newly created Pattern or an Inkscape provided
Pattern to an object. And the third is to adjust the
Pattern position and scaling as necessary.
Creating Patterns
Patterns are very easy to create. Simply select the object or
objects you wish to use as a Pattern and then use the
Object →
Objects to Pattern
After converting the selection to a Pattern, the original selection
is replaced by a
shape object
filled with the new Pattern (and with an invisible stroke).
This new object can be deleted but the Pattern will remain.
Patterns have a life of their own.
“tile” size of the Pattern is the total
objects in the Pattern. If space is required around the objects,
a non-visible rectangle object can be added or the Pattern size
can be edited with the
The object(s) in any Pattern can be edited by selecting an object
that is filled with that Pattern and then using the
Object →
Pattern to Objects
(Shift+Alt+I)
command. The original objects will reappear in their original place
(built-in Patterns will appear in the upper-left corner).
After editing, the objects can be again turned into a Pattern.
Both the old and new Patterns are available for use. Other objects
filled with the original Pattern remain unchanged. The new Pattern
must be “reapplied” to the object the Pattern came from.
Using Patterns
To change the fill of an object to a Pattern, simply click
on the Pattern icon (
in the Fill and Stroke dialog. Then select the required
Pattern from the pull-down menu. User created Patterns
will be listed first.
Unfortunately, there is no preview of the
Patterns (as with the Gradient tab).
If you want a Pattern to transform with
an object, you must toggle on this option using the
icon that is in the
is in use.
Adjusting Patterns
Adjusting Patterns is done by a set of handles. The
handles will appear when an object with a Pattern fill is
selected and the node or one of the shape tools is active.
handles will appear on the original objects that defined the
Pattern, or the former location of those objects if they
have been moved or deleted (unless the Pattern has been
previously adjusted). In the case of built-on Patterns
they will appear in the upper-left corner of the canvas. The
following figure shows the location of the handles for a
Pattern that has not been adjusted.
To adjust the origin, scale, and orientation of the Pattern, drag
the translation handle (×), scale handle (square), and rotation
handle (circle). The translation handle can conveniently be dragged
over the object with the Pattern fill. Holding the Ctrl
key down while dragging will restrict the movement to the horizontal or
vertical direction. The scale is governed by
the distance between the translation handle and scale handle, the
orientation by the relative position of the rotation handle with
the translation handle.
The x and y directions can be scaled independently.
Hold the Ctrl down to force the scaling to be
uniform. Handles can be snapped.
The following figure shows how the fill
changed after the handles have been adjusted.
viewers that don't support clipping,
you can crop a bitmap by turning the bitmap into a
Pattern and using it to fill an arbitrary path.
Inkscape now includes many Patterns that can be used as
hatchings.
If you need to create a new hatching, here is the
general procedure.
The simplest hatching is to group two
rectangular boxes, one with black fill and one with no fill as
shown below.
Inkscape has problems properly displaying Patterns at the Pattern
boundaries. Inkscape export to a
also has problems. To work around this
problem, you can make the Pattern rectangles wider than the maximum width
needed to fill an object. Firefox, Opera, and Batik will display patterns
without artifacts. Batik can be used for producing a high-quality .
Custom SwatchesNew in v0.48.
Custom Swatches allow per document palettes with swatches of
solid colors and . Custom Swatches are
automatically added to a special Auto
palette as they are created (selectable in the
dialog). Solid color swatches are implemented as
one-stop .
To create a Custom Swatch, with an object selected that has
the desired solid fill or Gradient, click on the
icon in the Fill and Stroke dialog (in
the Fill or Stroke paint tab as appropriate). After
creation, the color or Gradient of a swatch can be edited
using the Swatch fill section of the
Fill and Stroke dialog or by using the Gradient Editor
dialog that is accessed by selecting Edit...
in the menu that pops up when you Right Click on a
swatch in the
dialog (when the
Auto palette is displayed). Any change to a
swatch affects the fill of all objects that reference that
To assign a Custom Swatch to the fill of an object, either
select the desired swatch from the menu in the Swatch
fill section of the Fill and Stroke dialog (if a
swatch is already assigned to the fill) or click on the desired
swatch in the
dialog (if the
Auto palette is selected).
To delete a swatch, select Delete from the
menu that pops up when you Right Click on the
swatch in the
dialog (the
Auto palette must be selected). Note that
using File →
Vacuum Defs will not remove unused swatches.
The Fill Rule dictates what areas are filled
when a path overlaps itself or one part of a complex path
surrounds another part. The rule applies only to the
Fill of an object (and not the
Stroke paint).
One can choose the
Fill Rule from the two choices:
The difference between these rules is demonstrated in the following figures.
Even-odd rule.
In this rule, you start outside the path with the number
zero. Every time you cross the object's path, you add one to the
If the current number is odd, the region is inside the
path and therefore colored.
If the current number is even, the
region is outside the path and is not colored.
Non-zero rule.
In this rule, you start outside the path with the number
zero. Every time you cross the object's path with the path going
to the left, you add one to the number. If the path is going to the
right, you subtract one. If the number is non-zero, the region is
if it is zero, the region is outside the path.