Skip to content

Commit

Permalink
BCF-API #290 added object translucency support in viewpoints
Browse files Browse the repository at this point in the history
  • Loading branch information
Yoram Kulbak committed Jul 3, 2023
1 parent cdeb982 commit 77bfd48
Show file tree
Hide file tree
Showing 2 changed files with 106 additions and 0 deletions.
86 changes: 86 additions & 0 deletions Documentation/README.md
View file
Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,7 @@ The visualization information file contains information of components related to
The `Components` element contains the following properties.
* `Selection` to list components of interest
* `Visibility` to describe which component is visible and which isn't
* `Translucency` to describe which component is translucent and which isn't
* `Coloring` to convey coloring options for displaying components

#### Selection
Expand Down Expand Up @@ -310,6 +311,91 @@ In summary, after applying the following viewpoint:
</VisualizationInfo>
```

#### Translucency
The `Translucency` element decides which objects are translucent and which are opaque. Visibility has a higher priority than translucency: a translucent element which is also resolved to be invisible should not be rendered.

Element/Attribute | Optional | Description |
:-----------|:------------|:------------
DefaultTranslucency | Yes | Boolean. Defaults to `false`</br><ul><li>When `true`, all components should be translucent unless listed in the exceptions</li><li>When `false` all components should be opaque unless listed in the exceptions</li></ul>
Exceptions | Yes | A list of components to make opaque when `DefaultTranslucency=true` or to make translucent when `DefaultTranslucency=false`
TranslucencySetupHints | Yes | Boolean flags to allow fine control over the translucency of [spaces](https://standards.buildingsmart.org/IFC/RELEASE/IFC4_1/FINAL/HTML/schema/ifcproductextension/lexical/ifcspace.htm), [space boundaries](https://standards.buildingsmart.org/IFC/RELEASE/IFC4_1/FINAL/HTML/schema/ifcproductextension/lexical/ifcrelspaceboundary.htm) and [openings](https://standards.buildingsmart.org/IFC/RELEASE/IFC4_1/FINAL/HTML/schema/ifcproductextension/lexical/ifcopeningelement.htm). A typical use of these flags is when `DefaultTranslucency=false` but spaces, spaces boundaries and openings should remain translucent. </br>All flags default to `true`</br><ul><li>`SpacesTranslucent` - same as `DefaultTranslucency` but restricted to spaces only</li><li>`SpaceBoundariesTranslucent` - same as `DefaultTranslucency` but restricted to space boundaries only</li><li>`OpeningsTranslucent` - same as `DefaultTranslucency` but restricted to openings only</li></ul>

**Optimization Rules**

BCF is suitable for controlling the translucency of a few components. A huge list of translucent/opaque components will cause poor performance. When encoding a viewpoint follow these rules:

* Apply visibility optimization first and optimize translucency for visible components only.
* Omit the translucency element altogether if all visible components are opaque.
* If the list of translucent components is smaller than the list of opaque components: set `DefaultTranslucency` to false and put the translucent components in exceptions.
* If the list of opaque components is smaller or equals the list of translucent components: set `DefaultTranslucency` to true and put the opaque components in exceptions.
* If the size of exceptions is huge (over 1000 components), alert the user and ask them to alter the translucency setting to allow efficient encoding.
* For spaces, space boundaries and openings follow the these guideline (using spaces as an example): When a viewpoint has no opaque spaces, set the value of `SpacesTranslucent` to true. If there are any opaque spaces in the viewpoint, set the value to be the same as `DefaultTranslucency` and follow the optimization rules above while treating spaces like any other component.

##### Applying Translucency
Translucency is applied in following order:
1. Apply the `DefaultTranslucency`
2. Apply the `TranslucencySetupHints`
3. Apply the `Exceptions`

###### Example

Consider the viewpoint provided below.
1. Applying `DefaultVisibility="false"` hides all objects
2. Applying `SpacesVisible="true"` shows all spaces
3. Applying Visibility Exceptions inverting the Wall visibility makes it visible
4. Applying `DefaultTranslucency="false"` makes all objects opaque
5. Applying `SpacesTranslucent="true"` makes all spaces translucent
6. Applying Translucency Exceptions:
> 1. Inverting the Wall translucency makes it translucent
> 2. Inverting the Space translucency makes it opaque
> 3. Space boundaries and Openings remain invisible (visibility take priority over translucency)
In summary, after applying the following viewpoint:
1. All spaces are visible and translucent except one space which is visible and opaque
2. All the other objects are hidden except for one wall which is visible and translucent

``` xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<VisualizationInfo Guid="9e913da8-860c-4d48-9d94-ccccc2e1d9ca">
<Components>
<Selection/>
<Visibility DefaultVisibility="false">
<ViewSetupHints SpacesVisible="true" SpaceBoundariesVisible="false" OpeningsVisible="false"/>
<Exceptions>
<Component IfcGuid="1XbKhGD91DvhOpYZbhzGTI"/> <!-- Wall -->
</Exceptions>
</Visibility>
<Translucency DefaultTranslucency="false">
<TranslucencySetupHints SpacesTranslucent="true" SpaceBoundariesTranslucent="false" OpeningsTranslucent="true"/>
<Exceptions>
<Component IfcGuid="1XbKhGD91DvhOpYZbhzGTI"/> <!-- Wall -->
<Component IfcGuid="1bbI761TbBCOoIa5Kt6PXt"/> <!-- Space -->
</Exceptions>
</Translucency>
<Coloring/>
</Components>
<OrthogonalCamera>
<CameraViewPoint>
<X>18.674638207107783</X>
<Y>-19.54805982455614</Y>
<Z>10.538476791232824</Z>
</CameraViewPoint>
<CameraDirection>
<X>-0.8050867319107056</X>
<Y>0.5154458284378052</Y>
<Z>-0.29351478815078735</Z>
</CameraDirection>
<CameraUpVector>
<X>-0.24719256162643433</X>
<Y>0.15826167166233063</Y>
<Z>0.9559545516967773</Z>
</CameraUpVector>
<ViewToWorldScale>9.673289179801941</ViewToWorldScale>
<AspectRatio>1.7777777777777777</AspectRatio>
</OrthogonalCamera>
<ClippingPlanes/>
</VisualizationInfo>
```

#### Coloring
The `Coloring` element allows specifying the color of components. For each color a list of components to be displayed with the that color should be provided.
Expand Down
20 changes: 20 additions & 0 deletions Schemas/visinfo.xsd
View file
Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,7 @@
<!-- Components with relevance to the viewpoint. They should be displayed highlighted or selected in a viewer -->
<xs:element name="Selection" type="ComponentSelection" minOccurs="0"/>
<xs:element name="Visibility" type="ComponentVisibility" minOccurs="0"/>
<xs:element name="Translucency" type="ComponentTranslucency" minOccurs="0"/>
<xs:element name="Coloring" type="ComponentColoring" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
Expand Down Expand Up @@ -139,6 +140,25 @@
<xs:attribute name="SpaceBoundariesVisible" type="xs:boolean" default="false"/>
<xs:attribute name="OpeningsVisible" type="xs:boolean" default="false"/>
</xs:complexType>
<xs:complexType name="ComponentTranslucency">
<xs:sequence>
<xs:element name="TranslucencySetupHints" type="TranslucencySetupHints" minOccurs="0"/>
<xs:element name="Exceptions" minOccurs="0">
<!-- Inverses DefaultTranslucency and TranslucencySetupHints -->
<xs:complexType>
<xs:sequence>
<xs:element name="Component" type="Component" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="DefaultTranslucency" type="xs:boolean" default="false"/>
</xs:complexType>
<xs:complexType name="TranslucencySetupHints">
<xs:attribute name="SpacesTranslucent" type="xs:boolean" default="true"/>
<xs:attribute name="SpaceBoundariesTranslucent" type="xs:boolean" default="true"/>
<xs:attribute name="OpeningsTranslucent" type="xs:boolean" default="true"/>
</xs:complexType>
<xs:complexType name="ComponentColoring">
<xs:sequence>
<xs:element name="Color" minOccurs="0" maxOccurs="unbounded">
Expand Down

0 comments on commit 77bfd48

Please sign in to comment.