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IDLgrROIGroup Properties

IDLgrROIGroup 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 IDLgrROIGroup::GetProperty. Properties with the word “Yes” in the “Init” column of the property table can be set via IDLgrROIGroup::Init. Properties with the word “Yes” in the “Set” column in the property table can be set via IDLgrROIGroup::SetProperty.

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

Objects of this class have the following properties.

• ALL
• CLIP_PLANES
• DEPTH_TEST_DISABLE
• DEPTH_TEST_FUNCTION
• DEPTH_WRITE_DISABLE
• HIDE
• PARENT
• SHADER
• XCOORD_CONV
• XRANGE
• YCOORD_CONV
• YRANGE
• ZCOORD_CONV
• ZRANGE

In addition, objects of this class inherit:

• IDLanROIGroup
• IDLitComponent

ALL

An anonymous structure with the values of all of the properties associated with the state of this object.

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

Note: This structure returns ALPHA_CHANNEL and COLOR properties that are consistent with other graphic objects. However, neither property is used by the IDLgrROIGroup object.

CLIP_PLANES

A 4-by-N floating-point array that specifies the coefficients of the clipping planes to be applied to this object. The four coefficients for each clipping plane are of the form [A, B, C, D], where Ax + By + Cz + D = 0. Portions of this object that fall in the half space Ax + By + Cz + D > 0 will be clipped. By default, the value of this property is a scalar (-1) indicating that no clipping planes are to be applied.

Note: The clipping planes specified via this property are applied in addition to the near and far clipping planes associated with the IDLgrView in which this object appears.

Note: Clipping planes are applied in the data space of this object (prior to the application of any x, y, or z coordinate conversion).

Note: To determine the maximum number of clipping planes supported by the device, use the MAX_NUM_CLIP_PLANES property of the GetDeviceInfo method for the IDLgrBuffer, IDLgrClipboard, IDLgrWindow, and IDLgrVRML objects.

DEPTH_TEST_DISABLE

An integer value that determines whether depth testing is disabled.

• Set this property to 0 (the default) to inherit the value set by the parent model or view. The parent view always enables depth testing. A model may also enable or disable depth testing.
• Set this property to 1 to explicitly disable depth buffer testing while drawing this object.
• Set this property to 2 to explicitly enable depth testing for this object.

Disabling depth testing allows an object to draw itself “on top” of other objects already on the screen, even if the object is located behind them.

Note: Disabling depth testing also disables depth buffer writing. When disabling depth testing, the DEPTH_TEST_FUNCTION and DEPTH_WRITE_DISABLE properties are effectively ignored.

This property is registered as an enumerated list, but it is hidden by default.

DEPTH_TEST_FUNCTION

An integer value that determines the depth test function. Set this property to 0 (the default) to inherit the value set by the parent model or view. The parent view always sets a depth test function of LESS. A model may also set a depth test function value. The graphics device compares the object’s depth at a particular pixel location with the depth stored in the depth buffer at that same pixel location. If the comparison test passes, the object’s pixel is drawn at that location on the screen and the depth buffer is updated (if depth writing is enabled).

Set this property to any of the following values to use the desired function while rendering this object.

• 0 = INHERIT - use value from parent model or view.
• 1 = NEVER - never passes.
• 2 = LESS - passes if the object’s depth is less than the depth buffer’s value.
• 3 = EQUAL - passes if the object’s depth is equal to the depth buffer’s value.
• 4 = LESS OR EQUAL - passes if the object’s depth is less than or equal to the depth buffer’s value.
• 5 = GREATER - passes if the object’s depth is greater than or equal to the depth buffer’s value.
• 6 = NOT EQUAL - passes if the object’s depth is not equal to the depth buffer’s value.
• 7 = GREATER OR EQUAL - passes if the object’s depth is greater than or equal to the depth buffer’s value.
• 8 = ALWAYS - always passes

Less means closer to the viewer.

This property is registered as an enumerated list, but it is hidden by default.

DEPTH_WRITE_DISABLE

An integer value that determines whether depth writing is disabled.

• Set this property to 0 (the default) to inherit the value set by the parent model or view. The parent view always enables depth writing. A model may also enable or disable depth writing.
• Set this property to 1 to explicitly disable depth buffer writing while rendering this object.
• Set this property to 2 to explicitly enable depth writing for this object.

Disabling depth writing allows an object to be overdrawn by other objects, even if the object is located in front of them.

Note: If depth testing (see DEPTH_TEST_DISABLE property) is disabled, depth writing is also automatically disabled.

This property is registered as an enumerated list, but it is hidden by default.

HIDE

A Boolean value indicating whether this region group should be drawn:

• 0 = draw the region group (the default)
• 1 = do not draw the region group.

PARENT

An object reference to the object that contains this object.

SHADER

An object reference to an IDLgrShader object (or an object containing IDLgrShader as a superclass). When there is suitable graphics card hardware support, the ROI group is rendered using the GLSL shader program (executed on the graphics card) instead of using fixed OpenGL properties when initially drawn. (If a suitable graphics card is not present, IDL ignores the shader object when the scene is drawn.) A single IDLgrShader object may be associated with additional ROI group objects or other graphic objects that have the SHADER property.

XCOORD_CONV

A floating-point vector, [s₀, s₁], of scaling factors used to convert X coordinates from data units to normalized units. The formula for the conversion is as follows:

NormalizedX = s₀ + s₁*DataX

Recommended values are:

[(–X_min)/(X_max – X_min), 1.0/(X_max – X_min) ]

IDL converts, maintains, and returns this data as double-precision floating-point.

XRANGE

A two-element floating-point vector of the form [xmin, xmax] that specifies the range of x data coordinates covered by the graphic object. IDL maintains and returns this property in double-precision floating-point.

YCOORD_CONV

A floating-point vector, [s₀, s₁], of scaling factors used to convert Y coordinates from data units to normalized units. The formula for the conversion is as follows:

NormalizedY = s₀ + s₁*DataY

Recommended values are:

[(–Y_min)/(Y_max – Y_min), 1.0/(Y_max – Y_min) ]

IDL converts, maintains, and returns this data as double-precision floating-point.

YRANGE

A two-element floating-point vector of the form [ymin, ymax] that specifies the range of y data coordinates covered by the graphic object. IDL maintains and returns this property in double-precision floating-point.

ZCOORD_CONV

A floating-point vector, [s₀, s₁], of scaling factors used to convert Z coordinates from data units to normalized units. The formula for the conversion is as follows:

NormalizedZ = s₀ + s₁*DataZ

Recommended values are:

[(–Z_min)/(Z_max – Z_min), 1.0/(Z_max – Z_min) ]

IDL converts, maintains, and returns this data as double-precision floating-point.

ZRANGE

A two-element floating-point vector of the form [zmin, zmax] that specifies the range of z data coordinates covered by the graphic object. IDL maintains and returns this property in double-precision floating-point.