Shape

Description

Model Shape defines a visual shape that is shown at the location of its reference coordinate system, called 'object frame' below. All describing variables such as size and color can vary dynamically (with the only exception of parameter shapeType). The default equations in the declarations should be modified by providing appropriate modifier equations. Model Shape is usually used as a basic building block to implement simpler to use graphical components.

The following shapes are supported via parameter shapeType (e.g., shapeType="box"):
 

 
The dark blue arrows in the figure above are directed along variable lengthDirection. The light blue arrows are directed along variable widthDirection. The coordinate systems in the figure represent frame_a of the Shape component.

Additionally, external shapes can be specified as (not all options might be supported by all tools):

• "1", "2", ...
  define external shapes specified in DXF format in files "1.dxf", "2.dxf", ... The DXF-files must be found either in the current directory or in the directory where the Shape instance is stored that references the DXF file. This (very limited) option should not be used for new models. Example:
  shapeType="1".
  
• "modelica://<Modelica-name>/<relative-path-file-name>"
  characterizes the file that is stored under the location of the <Modelica-name> library path with the given relative file name. Example:
  shapeType = "../../../../../Resources/Data/Shapes/Engine/piston.dxf".
  
• "file://<absolute-file-name>"
  characterizes an absolute file name in the file system. Example:
  shapeType="file://C:/users/myname/shapes/piston.dxf".

The supported file formats are tool dependent. Most tools support at least DXF-files but may support other format as well (such as stl, obj, 3ds). Since visualization files contain color and other data, the corresponding information in the model is usually ignored. For information about DXF files, see Wikipedia. As a default it is assumed that the DXF coordinates are in the "frame_a"-system and in meters, and that the 3dfaces are two-sided. Some tools support only 3dface (for geometry) and layer (for advanced coloring).

The sizes of any of the above components are specified by the length, width and height variables. Via variable extra additional data can be defined:

shapeType	Meaning of parameter extra
"cylinder"	if extra > 0, a black line is included in the cylinder to show the rotation of it.
"cone"	extra = diameter-left-side / diameter-right-side, i.e., extra = 1: cylinder extra = 0: "real" cone.
"pipe"	extra = outer-diameter / inner-diameter, i.e, extra = 1: cylinder that is completely hollow extra = 0: cylinder without a hole.
"gearwheel"	extra is the number of teeth of the (external) gear. If extra < 0, an internal gear is visualized with |extra| teeth. The axis of the gearwheel is along "lengthDirection", and usually: width = height = 2*radiusOfGearWheel.
"spring"	extra is the number of windings of the spring. Additionally, "height" is not the "height" but 2*coil-width.
external shape	extra = 0: Visualization from file is not scaled. extra = 1: Visualization from file is scaled with "length", "width" and "height" of the shape

Parameter color is a vector with 3 elements, {r, g, b}, and specifies the color of the shape. {r, g, b} are the "red", "green" and "blue" color parts. Note, r, g, b are given as Integer[3] in the ranges 0 .. 255, respectively. The predefined type MultiBody.Types.Color contains a menu definition of the colors used in the MultiBody library together with a color editor.

The variables under heading Parameters below are declared as (time varying) input variables. If the default equation is not appropriate, a corresponding modifier equation has to be provided in the model where a Shape instance is used, e.g., in the form

Visualizers.Advanced.Shape shape(length = sin(time));