Vector_Postscript - converts a Geometry Edit List to vector PostScript
Name
Vector_Postscript - converts a Geometry Edit List to vector PostScript
Summary
Name Vector_Postscript
Type Render
Inputs Geometry Edit List
Outputs None
Parameters Colour_Mode Radio Buttons
Draw_Mode Radio Buttons
Polygon_Resolution Integer Slider
Sphere_Resolution Integer Slider
Polygon_and_Lines_of_same_Object Toggle
Text_Scale Float Slider
Overall_Scale Float Slider
File_Selector File Browser
Press_Me_To_Draw_EPS_File Toggle
Description
The Vector_Postscript module takes as its input
a standard Geometry Edit List
as is normally supplied to the Geometry Viewer. On activating the
"Press_Me" button, the module will attempt to convert the information
stored in the Geometry Edit List into a 2D vector PostScript file
which is specified by the "File_Selector". Polygons are shaded using
a simple Phong shading model with a set light source, as are spheres,
which are first triangulated before rendering. The postscript file
contains no "raster" sections; it has geometric definitions taken
from the original scene, so that it will be printed at the highest
availalbe device resolution. Unlike the standard postscript output
from AVS, this one scales output file size by scene complexity rather
than window size.
The module offers many controls over the colour and quality of the
final PostScript file.
The module takes most of its information from the Geometry Edit List,
but does get additional infomation from the Geometry Viewer, such as
the roatation and scaling matrices of any objects to be drawn, as well
as any colour properties that have been assigned by the user.
Additionally the module looks to the Geometry Viewer to see if
Perspective, Depth-Cueing and Front-Clipping are on or off, and then
implements these functions appropriately. The background camera colour
is also reprodcued.
The module reproduces most Geometry Views, however cannot draw objects
that are set to be Non-Transformable, i.e. text titles and objects such
as the Color Legend module's output.
Parameters
Colour_Mode
The colour mode allows the user to select from Colour, GreyScale
or Black and White drawing options. Colour and GreyScale modes
attempt to reproduce the screen colours as well as they can, and
B/W mode draws objects usually as black on white or white on
black depending upon the background colour of the Geometry Viewer.
Draw_Mode
Draw_Mode determines how the objects on screen are to be rendered
to the Postscript file. In Solid mode, polygons and spheres are
drawn as shaded, solid objects. In Wireframe mode they are drawn
with just their outlines shown. The Outline mode draws the solid
polygons as well as showing the wireframe outline of each polygon.
Polygon_Resolution
Sphere_Resolution
By default all solid objects are split into triangles before
being drawn. By increasing the resolution factor, each triangle
can be further split into 4 smaller triangles and rendered
seperately. By doing this, the roundness of a sphere can be
greatly improved (using the Sphere_Resolution) and the shading
on a polygon object can be improved with the Polygon_Resolution.
However the greater the resolution, the greater the file size
and the longer the system takes to render. The table below shows
the scaling factor used by the resolution controls
---------------------------------------------------------
Resolution 1 2 3 4
---------------------------------------------------------
Triangles 8 32 128 512
to draw a sphere
Triangle 1 8 32 128
---------------------------------------------------------
Polygon_and_Lines_of_same_Object
Quite often a polygon object is composed of triangles and lines.
In most cases these lines need not be drawn. This switch forces
any lines that accompany a polygn to be drawn or not drawn. When
then button is selected (white) then lines are drawn as well as
polygon objects. By default this button is set to off.
Text_Scale
Text sizes are difficult to scale up or down automatically. The
module attempts to choose the correct text size in all cases, and
this slider then adds a further degree of control over these
selected text sizes. The scale is a simple multiplication factor
running from 0.5 (half size) to 2 (double size text).
Overall_Scale
The overall_scale slider allows the whole scale of the picture
to be changed, from half size (0.5) up to double size (2). The
picture is always centred on the page.
File_Selector
The file_selector is a standard AVS browser that is used to
specify the output file to write to.
Press_Me_To_Draw_EPS_File
Finally, selecting this button will cause the module to actually
perform the Edit_List --> PostScript conversion. The button will
revert to unselected mode when the module has finished.
Example networks
Read Geom
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Geometry Viewer Vector_Postscript