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<TITLE>About the SLUDGE Z-Buffer Maker</TITLE>
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<div align="center"><img id="headerGraphic" src="images/sludge300.png" alt="SLUDGE"/></div>
<h2>About the SLUDGE Z-Buffer Maker</h2>
<HR>
<P>
The SLUDGE Z-Buffer Maker is used to create different areas of a scene which can
obscure character graphics, such as foreground silhouettes, doorframes and furniture.
</P>
<H3>Creating a z-buffer image:</H3>
<P>
The main work - specifying the areas - cannot be done from within the program itself
and must instead be done using a paint package. For example, take the following room
(taken from one of the demos):
</P>
<P>
<IMG SRC="images/image002.gif">
</P>
<P>
The above room image has the following z-buffer image:
</P>
<P>
<IMG SRC="images/image003.gif">
</P>
<P>
(The size and quality of these images has been reduced for the sake of this
documentation - full versions of both images can be found as part of the verb
coin example.)
</P>
<P>
Mixing these images together shows the concepts behind the z-buffer image, and
which layers correspond with which areas in the actual image. Note that <b>this
is not a required stage of producing a z-buffer image</b>; it is here only as an
aid to understanding the reasons behind creating the image shown above.
</P>
<P>
<IMG SRC="images/image004.gif">
</P>
<P>
A z-buffer image must have a black background and coloured areas that define where
characters will be obscured by parts of the scene. You are allowed a maximum of 16
different colours - each colour will be treated as a different layer.
</P>
<H3>Loading your z-buffer image into the SLUDGE z-buffer maker:</H3>
<P>
Save your z-buffer image as an uncompressed TGA file and open it in the SLUDGE
Z-Buffer Maker using the <b>New from TGA image</b> command on the <b>File</b> menu
(Win/Linux) or <b>New zBuffer from TGA image</b> command on the <b>Tools</b> menu.
After loading the image from above, the Z-Buffer Maker looks like this:
</P>
<P>
<IMG SRC="images/zbuffermaker.png">
</P>
The slider at the top of the window is used to select a layer, the selected
layer is displayed in white and the <b>y(z)</b> field used to set the cut-off point
of the selected layer. The cut-off point of the selected layer is also shown by a
green horizontal line.</p>
<p>Windows/Linux: The cut-off point can also be set using the left mouse button.
If your scene is larger than the SLUDGE Z-Buffer Maker window, you can scroll
around the image by holding down the right mouse button and dragging the mouse
in the direction in which you wish to move.
</p>
<p>Mac: The image can be scrolled by dragging the mouse and zoomed in/out by
two-finger scrolling. The cut-off point can be adjusted by holding down Command
and dragging the mouse.</p>
<H3>Cut-off points:</H3>
<P>
The purpose of the Z-Buffer Maker is to associate cut-off points to the layers
defined by the z-buffer image. The cut-off point is the y-value below which a
character must be standing in order to be shown in front of the layer in question.
By default, when a TGA image is loaded, the cut-off point for each layer is the
y-value of the lowest pixel used in the layer.
</P>
<P>
For example, the cut-off points for the above example are initially set to the
following: layer 1 (cyan) has a y-value of 479, layer 2 (green) has a y-value of
392 and layer 3 (red) has a y-value of 296.
</P>
<P>
It is possible to set a cut-off point to a larger value than the height of the
screen, which is useful if you want to move a character off the bottom of the
screen but still have them obscured by an object.
</P>
<H3>Saving and using a z-buffer file:</H3>
<P>
To save your z-buffer file in the format used by SLUDGE, open the <b>File</b> menu
and choose <b>Save</b> or <b>Save as...</b>. The <b>Save</b> option will overwrite
the z-buffer file from which the current data was loaded... if the current data
was loaded from an image file, it will do the same as the
<b>Save as...</b> option, which allows you to save the data under any file name.
</P>
<P>
To load your z-buffer file into a game, use the <a href="setZBuffer.html">setZBuffer
</a> function with its <a href="File_Handling.html">file handle</a> as the parameter.
To remove a z-buffer from memory in your game, call the same function with NULL
as the parameter.
</P>
<P class="copyright-notice">SLUDGE and this SLUDGE documentation are <A HREF="Copyright.html">copyright</A> Hungry Software and contributors 2000-2012
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