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<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="plug-in-lighting"></a>9.4. Lighting Effects</h3>
</div>
</div>
</div>
<a id="id3365715" class="indexterm"></a>
<div class="mediaobject">
<img src="../images/filters/filters-light-lightingeffects.png" />
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3365725"></a>Overview</h4>
</div>
</div>
</div>
<p>
This filter is found in
<span class="guimenuitem">Image>Filters/Light Effects/<span class="accel">L</span>ighting Effects</span>.
</p>
<p>
This filter simulates the effect you get when you light up a wall with a spot. It doesn't
produce any drop shadows and, of course, doesn't reveal any new details in dark zones.
</p>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3365214"></a>Preview</h4>
</div>
</div>
</div>
<p>
When <span class="guilabel">Interactive</span> is checked, parameter setting results are
interactively displayed in preview without modifying the image until you click on
<span class="guilabel">OK</span> button.
</p>
<p>
If "Interactive" is not checked, changes are displayed in preview only when you click
on the <span class="guilabel">Update</span> button. This option is useful with a slow computer.
</p>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3365162"></a>General Options</h4>
</div>
</div>
</div>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<span class="guilabel">Transparent Background</span>: Makes destination image transparent when
bumpmap height is zero (height is zero in black areas of the bumpmapped image).
</p>
</li>
<li>
<p>
<span class="guilabel">Create New Image</span>: Creates a new image when applying filter.
</p>
</li>
<li>
<p>
<span class="guilabel">High Quality Preview</span>: For quick CPU...
</p>
</li>
<li>
<p>
<span class="guilabel">Enable Antialiasing</span>: Lowers the scale effect on lines.
<span class="emphasis"><em>Depth</em></span> is the strength of antialiasing.
<span class="emphasis"><em>Threshold</em></span> determines which transitions will be
considered as a border. High values will limit the effect
to strong transitions.
</p>
</li>
</ul>
</div>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3365628"></a>Light</h4>
</div>
</div>
</div>
<div class="variablelist">
<dl>
<dt>
<span class="term">Light Settings</span>
</dt>
<dd>
<p>
<span class="guilabel">Light Type</span>: Three types are available.
<span class="emphasis"><em>Point</em></span>
displays a blue point at center of preview. You can click and
drag it to move light all
over the preview. <span class="emphasis"><em>Directional</em></span>: the blue point
is linked to preview
center by a line which indicates direction of light. The white light halo has an
elliptic shape. <span class="emphasis"><em>None</em></span>: there is no blue point. Light comes
from the top left corner, the best to give a good relief effect.
</p>
<p>
<span class="guilabel">Light Source Color</span>: When you click on the color dwell,
you bring a
dialog up where you can select the light source color.
</p>
<p>
<span class="guilabel">Position</span>: Determines the light point position
according to three coordinates: X coordinate for horizontal position,
Y for vertical position, Z for source
distance (the light darkens when distance increases). Values are from -1 to +1.
</p>
</dd>
</dl>
</div>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3365803"></a>Material</h4>
</div>
</div>
</div>
<div class="variablelist">
<dl>
<dt>
<span class="term">Intensity Levels</span>
</dt>
<dd>
<p>
These options don't concern light itself, but light reflected by objects.
</p>
<p>
<span class="guilabel">Ambient</span>: Sets the ambient light, i.e the indirect light which
lightens all the scene out of the light spot
</p>
<p>
<span class="guilabel">Diffuse</span>: When you increase this value,
light progressively diffuses to the whole image
</p>
</dd>
<dt>
<span class="term">Reflectivity</span>
</dt>
<dd>
<p>
<span class="guilabel">Diffuse</span>: Higher values make the object reflect more light.
</p>
<p>
<span class="guilabel">Specular</span>: Controls how intense will be the highlights.
</p>
<p>
<span class="guilabel">Highlights</span>: Higher values make the highlights more focused.
</p>
</dd>
</dl>
</div>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3365508"></a>Bump Map</h4>
</div>
</div>
</div>
<div class="variablelist">
<dl>
<dt>
<span class="term">Enable Bump Mapping</span>
</dt>
<dd>
<p>
Combined with "Environment Map", this option allows interesting bump mapping. Only
greyscale images can be used for bumpmaps (light areas are bumped, dark areas remain
unchanged). So, if you want to bumpmap against a RGB image, you have to turn it to
greyscale first (<Image>Image/Mode/Grayscale). When you check this box, following
options are enabled:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<span class="guilabel">Bump Map Image</span>: You have to select there the greyscale image.
</p>
</li>
<li>
<p>
<span class="guilabel">Curve</span>: Four curve types are available:
<span class="emphasis"><em>Linear</em></span>,
<span class="emphasis"><em>Logarithmic</em></span>, <span class="emphasis"><em>Sinusoidal</em></span> and
<span class="emphasis"><em>Spherical</em></span>. See Bump Map plug-in for explanations.
</p>
</li>
<li>
<p>
<span class="guilabel">Maximum Height</span>: This is the maximum height of bumps.
</p>
</li>
<li>
<p>
<span class="guilabel">Minimum Height</span>: This is the minimum height of bumps.
</p>
</li>
<li>
<p>
<span class="guilabel">Autostretch to fit Value Range</span>: There is correspondence
between grey level and height. If difference between black and lightest
grey is not enough to
fill the height value range determined above, then values are stretched.
</p>
</li>
</ul>
</div>
</dd>
</dl>
</div>
</div>
<div class="simplesect" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id3365758"></a>Environment Map</h4>
</div>
</div>
</div>
<div class="variablelist">
<dl>
<dt>
<span class="term">Enable Environment Mapping</span>
</dt>
<dd>
<p>
When you check this box, the following option is enabled:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<span class="guilabel">Environment Image</span>: You have to select there a RGB image.
</p>
</li>
</ul>
</div>
</dd>
</dl>
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