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IDLgrView Properties

IDLgrView Properties

IDLgrView objects have the following properties in addition to properties inherited from any superclasses. Properties with the word “Yes” in the “Get” column of the property table can be retrieved via IDLgrView::GetProperty. Properties with the word “Yes” in the “Init” column of the property table can be set via IDLgrView::Init. Properties with the word “Yes” in the “Set” column in the property table can be set via OUT_RANGE.

Note: For a discussion of the property description tables shown below, see Modifying Object Property Descriptions.

Objects of this class have the following properties.

In addition, objects of this class inherit:

ALL

An anonymous structure containing the values of all of the properties associated with the state of this object. State information about the object includes things like color, range, tick direction, etc., but not image, vertex, or connectivity data, or user values.

Note: The fields of this structure may change in subsequent releases of IDL.

Property Type

Structure

Name String

not displayed

Get: Yes

Set: No

Init: No

Registered: No

COLOR

The color for the view. This is the color to which the view area will be erased before its contents are drawn. The color may be specified as a color lookup table index or as a three-element vector [red, green, blue]. The default is [255, 255, 255] (white).

In a property sheet, this property appears as a color property.

Property Type

COLOR

Name String

Color

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

DEPTH_CUE

A two-element floating-point array [zbright, zdim] specifying the near and far Z planes between which depth cueing is in effect. Depth cueing is only honored when drawing to a destination object that uses the RGB color model.

Depth cueing causes an object to appear to fade into the background color of the view object with changes in depth. If the depth of an object is further than zdim (that is, if the object’s location in the Z direction is farther from the origin than the value specified by zdim), the object will be painted in the background color. Similarly, if the object is closer than the value of zbright, the object will appear in its “normal” color. Anywhere in-between, the object will be a blend of the background color and the object color. For example, if the DEPTH_CUE property is set to [-1,1], an object at the depth of 0.0 will appear as a 50% blend of the object color and the view color.

The relationship between Zbrightand Zdim determines the result of the rendering:

  • Zbright < Zdim: Rendering darkens with depth.
  • Zbright > Zdim: Rendering brightens with depth.
  • Zbright = Zdim: Disables depth cueing.

You can disable depth cueing by setting zbright = zdim. The default is [0.0, 0.0].

This property is registered as a user-defined property, but it is hidden by default.

Property Type

USERDEF

Name String

Depth cue

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

DIMENSIONS

A two-element integer vector of the form [width, height] specifying the dimensions of the viewport (the rectangle in which models are displayed on a graphics destination). By default, the viewport dimensions are set to [0, 0], which indicates that it will match the dimensions of the graphics destination to which it is drawn. The dimensions are measured in the units specified by the UNITS property.

Property Type

Integer vector

Name String

not displayed

Get: Yes

Set: Yes

Init: Yes

Registered: No

DOUBLE

A Boolean value that controls the precision used for rendering the entire contents of the view. If set, IDL calculates the transformations used for the modeling and view transforms using double-precision floating-point arithmetic. This allows the values specified for the VIEWPLANE_RECT, modeling transforms in IDLgrModel objects, and coordinate data in atomic graphic objects to be used as double-precision before mapping to device coordinates.

Note: If this property is set to 0, IDL uses single-precision floating-point arithmetic for these values, which can cause loss of significance and incorrect rendering of data. Setting this property to 1 may impact graphics performance and should only be used when handling data requiring double precision.

The default value is 0.

Property Type

Boolean

Name String

Double precision

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

EYE

A floating-point value that specifies the distance from the eyepoint to the viewplane (Z=0). The default is 4.0. The eyepoint is always centered within the viewplane rectangle. (That is, if the VIEWPLANE_RECT property is set equal to [0,0,1,1], the eyepoint will be at X=0.5, Y=0.5.) IDL converts, maintains, and returns this data as double-precision floating-point.

Property Type

FLOAT

Name String

Eye distance

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

HIDE

A Boolean value or enumerated list item indicating whether this object should be drawn:

Value

Property Sheet Value

Description

0

True

Draw graphic (the default)

1

False

Do not draw graphic

 

Property Type

ENUMLIST

Name String

Show

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

LOCATION

A two-element floating-point vector of the form [x, y] specifying the position of the lower left corner of the view. The default is [0, 0], and is measured in units specified by the UNITS property

This property is registered as a user-defined property, but it is hidden by default.

Property Type

USERDEF

Name String

Viewport location

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

PARENT

An object reference to the object that contains this object.

Property Type

Object reference

Name String

not displayed

Get: Yes

Set: No

Init: No

Registered: No

PROJECTION

An integer value or enumerated list item indicating the type of projection to use within this view. All models displayed within this view will be projected using this type of projection. Valid values are:

Value

Property Sheet Value

Description

0

None

Same result as setting Orthogonal or 1

1

Orthogonal

Models are projected along lines perpendicular to the view plane (the default)

2

Perspective

Models are projected toward the eye (located at the origin), which is the apex of the viewing frustum. With a perspective projection, models that are farther away from the eye will appear smaller in the view than models that are nearer to the eye.

 

Property Type

ENUMLIST

Name String

Projection

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

REGISTER_PROPERTIES

A Boolean value that determines whether to register properties available for this object. If this property is set, all properties marked in this properties section as “Registered: Yes” will be registered for display in a property sheet. This property is useful mainly when creating iTools. By default, no properties are registered.

Property Type

Boolean

Name String

not displayed

Get: No

Set: No

Init: Yes

Registered: No

TRANSPARENT

A Boolean value that determines whether to disable the viewport erase, making the viewport transparent. If this value is false, the viewport is erased and the depth buffer initialized. If this value is true, the viewport is not erased and the depth buffer is not initialized.

Property Type

Boolean

Name String

Transparent

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

UNITS

An integer value or enumerated list item that specifies the units of measure for this view:

Value

Property Sheet Value

Description

0

Device

Device units are unit of measure (the default)

1

Inches

Inches are unit of measure

2

Centimeters

Centimeters are unit of measure

3

Normalization

Normalized units (relative to the graphics destination’s rect) are unit of measure

Note: If you set the UNITS property (using the SetProperty method) of a view without also setting the LOCATION and DIMENSIONS properties, IDL will use the existing size and location values in the new units, without conversion. This means that if your view’s location and dimensions were previously measured in centimeters, and you change the value of UNITS to 1 (measurement in inches), the actual size of the view object will change.

Property Type

ENUMLIST

Name String

Units

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

VIEWPLANE_RECT

A four-element floating-point vector of the form [x, y, width, height] to describe the bounds in x and y of the view volume. Objects within the view volume are projected into the viewport. These values are measured in normalized space. The default is [-1.0, -1.0, 2.0, 2.0] IDL converts, maintains, and returns this data as double-precision floating-point.

Note: The z bounds of the view volume are set via the ZCLIP property. The viewplane rectangle is always located at Z=0.

This property is registered as a user-defined property, but it is hidden by default.

Property Type

USERDEF

Name String

Viewplane rectangle

Get: Yes

Set: Yes

Init: Yes

Registered: Yes

ZCLIP

A two element floating-point vector representing the near and far clipping planes to be applied to the objects in this view. The vector should take the form [near, far]. By default, these values are [1, -1]. IDL converts, maintains, and returns this data as double-precision floating-point.

This property is registered as a user-defined property, but it is hidden by default.

Property Type

USERDEF

Name String

Z clipping

Get: Yes

Set: Yes

Init: Yes

Registered: Yes



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