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BILD Format

BILD is a simple text format that describes lines, polygons, and simple shapes such as spheres, boxes, cylinders, and cones (see example.bild and XYZ-axes.bild). The objects can be specified in absolute coordinates and/or transformed and scaled coordinates. This input format is indicated by the filename suffix .bild or .bld, or with the format bild option in the open command. See also: struts, 3D object formats

Curved objects (spheres, cones, and cylinders) read from BILD format are displayed within ChimeraX using planar facets. Lines are implemented as very thin cylinders (radius 0.08).

BILD Directives

Square brackets denote optional parameters.

.arrow x1 y1 z1 x2 y2 z2 [r1 [r2 [rho]]]
Draw an arrow from (x1, y1, z1) to (x2, y2, z2). An arrow consists of a cylinder stretching from the initial point to an intermediary junction, and a cone stretching from the junction to the final point. The radius of the cylinder is r1 (default 0.1), the radius of the base of the cone is r2 (default 4*r1), and the fraction of the total distance taken up by the cylinder is rho (default 0.75).
.associate atom-spec
Specify one or more atoms to associate with subsequently defined items (geometric objects) for purposes of selection. In other words, selecting the atoms will select the object(s) and vice versa. Selecting only a subset of the associated atoms, however, will not automatically select an object. Multiple objects associated with the same set of atoms can only be selected collectively, not individually. Using .associate with a blank specification indicates that subsequently defined objects should not be associated with any atoms.
.box x1 y1 z1 x2 y2 z2
Draw a box with opposite corners at (x1, y1, z1) and (x2, y2, z2).
.color name
or
.color r g b

Set the color of subsequently defined items. The name can be a built-in name, a name defined previously with color name, or an integer that refers to the old BILD color wheel (0-65, inclusive). Alternatively, a color can be described by its red (r), green (g), and blue (b) components, each in the range 0-1, inclusive. Any transparency in the color is ignored, but transparency can be set separately.
.comment text
User comment line (ignored during object creation). See also .note.
.cone x1 y1 z1 x2 y2 z2 r [open]
Draw a cone with a base of radius r centered at (x1, y1, z1) and a tip at (x2, y2, z2). If the keyword open is present, the base of the cone will be invisible.
.cylinder x1 y1 z1 x2 y2 z2 r [open]
Draw a cylinder with radius r and bases centered at (x1, y1, z1) and (x2, y2, z2). If the keyword open is present, the bases of the cylinder will be invisible.
.dotat x y z
or
.dot x y z

Draw a sphere of unit radius centered at (x, y, z). The sphere center is treated as a vertex if there is a subsequent .draw, .drawrel, or .moverel command.
.draw x y z
or
.d x y z

Add another vertex to the current set of line segments. A line will be drawn from the previous vertex to this vertex at (x, y, z). There should be a prior .move, .moverel, .dotat, or .marker command (these initiate sets of line segments).
.drawrel dx dy dz
or
.dr dx dy dz

Add another vertex to the current set of line segments. A line will be drawn from the previous vertex at (x, y, z) to this vertex at (x + dx, y + dy, z + dz).
.marker x y z
Draw a box of unit cubic diagonal centered at (x, y, z), i.e., a box with opposite corners at (x – 0.5, y – 0.5, z – 0.5) and (x + 0.5, y + 0.5, z + 0.5). The box center is treated as a vertex if there is a subsequent .draw, .drawrel, or .moverel command.
.move x y z
or
.m x y z

Start a new set of line segments whose first vertex is at (x, y, z).
.moverel dx dy dz
or
.mr dx dy dz

Start a new set of line segments whose first vertex is at (x + dz, y + dy, z + dz), where (x, y, z) is the coordinate of the last vertex defined.
.note text
Balloon label (to appear upon mouseover) for subsequently defined items, instead of the generic “object N: object_type” information that would otherwise appear. Using .note without any text restores the default behavior for subsequently defined items. See also .comment.
.polygon x1 y1 z1 x2 y2 z2 ... xN yN zN
Draw a flat polygon with vertices at (x1, y1, z1), (x2, y2, z2), ..., (xN, yN, zN).
.pop
Discard the most recent transformation (rotation, scaling, or translation) from the transformation stack.
.rotate angle axis
or
.rot angle axis

Rotate all subsequent coordinates by angle degrees about the given axis. The axis can be given as a single letter (x, y, or z) or as three numbers defining an arbitrary vector: xa ya za. This transformation is added to the top of the transformation stack.
.scale xscale [yscale [zscale]]
Scale all subsequent coordinates by the given factor(s). The x coordinates will be scaled by xscale, y coordinates by yscale (equal to xscale by default), and z coordinates by zscale (equal to xscale by default). This transformation is added to the top of the transformation stack.
.sphere x y z r
Draw a sphere centered at (x, y, z) with radius r.
.translate dx dy dz
or
.tran dx dy dz

Translate all subsequent coordinates by the specified amount. This transformation is added to the top of the transformation stack.
.transparency value
Set the transparency of subsequently defined items. The value can range from 0.0 (not transparent) to 1.0 (completely transparent).
.vector x1 y1 z1 x2 y2 z2
or
.v x1 y1 z1 x2 y2 z2
Draw a line segment from (x1, y1, z1) to (x2, y2, z2). This command is a shorthand for
.m x1 y1 z1
.d x2 y2 z2

UCSF Resource for Biocomputing, Visualization, and Informatics / November 2017