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Plot header commands

The plot header consists of a set of commands which must be placed before any graphics commands in the input command file, if they are to be included at all. These commands control various global aspects of the rendered image. They may be given in any order within the header section.

noframe

Remove the frame that is drawn by default around the plot. There must be no semi-colon after this command!

This is a badly designed command that has been retained in v2 just for backwards compatibility. It may be removed in future versions. Use the frame command instead.

Note: There is no semi-colon ';' after this command!
Used for: PostScript only

frame < on | off > ;

Switch on or off drawing of the frame around the plot. The plot extent on the paper is given by the area command.

Default: on
Used for: PostScript only

area number number number number ;

Determine where on the paper the plot will be placed. The values given are the x and y coordinates for the lower left corner, followed by the x and y coordinates for the upper right corner, in PostScript units. The default values are appropriate for A4 size (European standard) or Letter size (US standard) paper. A frame (a black rectangle) is drawn around the area, unless the "frame off;" command is used.

Default: 50.0 100.0 550.0 700.0
Used for: PostScript only

background colour-spec ;

Determines the colour of the background in the image.

Default: white for PostScript, black for Raster3D, VRML 2.0, OpenGL

window number ;

Set the length of the side of the coordinate system volume that is viewed. Since the view is always towards the origin of the coordinate system (0, 0, 0), the coordinates at the edge of the viewed volume will be half the window value (if the area is quadratic): For example, at the right the coordinate will be (window/2, y, z), at the left (-window/2, y, z). The window will always be fitted into the plot area. If the plot area is non-square, the actual window will be larger in either x or y (depending on the aspect ratio) than the specified window value.

A large value for window means that a large volume is viewed, making the objects small. Conversely, a small value enlarges the objects and views a smaller part of the coordinate system space.

If no explicit window value is set, MolScript computes a value that just encompasses the objects rendered. That value is then output as a message. This means that the scale of the image (the relation Ångström : display units) will depend on what is drawn and may vary according to the transformation applied to the coordinates. To obtain a constant scale, set the window value explicitly. This is important when different views are shown of the same graphical objects, such as stereo plots.

In the PostScript output mode, the graphics segments outside the window are not written to the output file, in order to minimize the file size.

The window value is ignored for the VRML 2.0 output mode.

Default: A value that just fits the drawn graphics objects.
Used for: PostScript, Raster3D, OpenGL.

slab number ;

Set the depth of the coordinate system volume box that is viewed. Graphical segments that fall outside this volume are clipped. If a small value is given, then only a thin slice of the coordinate space is visible. Since the view is alway towards the origin of the coordinate system (0, 0, 0), the coordinates at the view volume front edge will be (x, y, slab/2) and at the volume back edge (x, y, -slab/2).

If no explicit slab value is given, MolScript computes a value that just encompasses the objects drawn in the plot. That value is then output as a message. Certain depth cue effects (such as the effect on the coil radius) in the PostScript output mode depend on an explicitly set slab value, otherwise they are not applied.

The slab value has no meaning for the VRML 2.0 output mode.

Default: A value that just fits the drawn graphics objects.
Used for: PostScript, Raster3D, OpenGL.

headlight < on | off > ;

Switch on or off the headlight, the default light source. If switched off, then some other light(s) should be defined in the input file, or the objects will not be illuminated.

Default: on
Used for: Raster3D, VRML 2.0, OpenGL

shadows < on | off > ;

Determine whether shadows for the graphics objects are to be computed in ray-tracing rendering.

Default: off
Used for: Raster3D only

fog number ;

Set the value of the global fog distance parameter. If the value is non-zero, the colour of every graphical segments is blended with the background colour according to the distance from the front slab plane (OpenGL) or viewer (VRML 2.0). The parameter is the distance where the background colour completely dominates. Beyond this distance, no objects will be visible. A simple linear fog equation is used.

This is the replacement for the now defunct colourdepthcue parameter.

Default: 0.0
Used for: VRML 2.0, OpenGL

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