- Create a new Actor called PostEditChangePropertyActor based on StaticMeshActor:<\/li><\/ol>\n\n\n\n
![\"\"\/](\"http:\/\/blog.coolcoding.cn\/wp-content\/uploads\/2021\/01\/45976a36-1621-403c-973b-afa3c859cabe.png\")
<\/figure>\n\n\n\n- Add the following UPROPERTY and function definition to the class:<\/li><\/ol>\n\n\n\n
UCLASS()
class CHAPTER_09_API APostEditChangePropertyActor : public
AStaticMeshActor
{
GENERATED_BODY()
\/\/ Sets default values for this actor's properties<\/strong>
APostEditChangePropertyActor();<\/strong>
UPROPERTY(EditAnywhere)<\/strong>
bool ShowStaticMesh = true;<\/strong>
virtual void PostEditChangeProperty(FPropertyChangedEvent&
PropertyChangedEvent) override;<\/strong>
};<\/pre>\n\n\n\n- Create the class constructor by adding the following code to the PostEditChangePropertyActor.cpp file:<\/li><\/ol>\n\n\n\n
#include \"PostEditChangePropertyActor.h\"
#include \"ConstructorHelpers.h\"<\/strong>
APostEditChangePropertyActor::APostEditChangePropertyActor()<\/strong>
{<\/strong>
\/\/ Set this actor to call Tick() every frame. You can turn
\/\/ this off to improve performance if you don't need it.<\/strong>
PrimaryActorTick.bCanEverTick = true;<\/strong>
auto MeshAsset = ConstructorHelpers::FObjectFinder<UStaticMesh>
(TEXT(\"StaticMesh'\/Engine\/BasicShapes\/Cone.Cone'\"));<\/strong>
UStaticMeshComponent * SM = GetStaticMeshComponent();<\/strong>
if (SM != nullptr)<\/strong>
{<\/strong>
if (MeshAsset.Object != nullptr)<\/strong>
{<\/strong>
SM->SetStaticMesh(MeshAsset.Object);<\/strong>
SM->SetGenerateOverlapEvents(true);<\/strong>
}<\/strong>
SM->SetMobility(EComponentMobility::Movable);<\/strong>
}<\/strong>
}<\/strong><\/pre>\n\n\n\n- Implement PostEditChangeProperty:<\/li><\/ol>\n\n\n\n
void APostEditChangePropertyActor::PostEditChangeProperty( FPropertyChangedEvent& PropertyChangedEvent)
{
\/\/ Check if property is valid
if (PropertyChangedEvent.Property != nullptr)
{
\/\/ Get the name of the changed property
const FName PropertyName(
PropertyChangedEvent.Property->GetFName());
\/\/ If the changed property is ShowStaticMesh then we
\/\/ will set the visibility of the actor
if (PropertyName == GET_MEMBER_NAME_CHECKED(
APostEditChangePropertyActor, ShowStaticMesh))
{
UStaticMeshComponent * SM = GetStaticMeshComponent();
if (SM != nullptr)
{
SM->SetVisibility(ShowStaticMesh);
}
}
}
\/\/ Then call the parent version of this function
Super::PostEditChangeProperty(PropertyChangedEvent);
}<\/pre>\n\n\n\n- Compile your code and launch the editor.<\/li>
- Drag an instance of your class into the game world and verify that toggling the Boolean value for ShowStaticMesh toggles the visibility of the mesh in the editor viewport:<\/li><\/ol>\n\n\n\n
![\"\"\/](\"http:\/\/blog.coolcoding.cn\/wp-content\/uploads\/2021\/01\/dba850f4-0119-4dac-85a7-e24f6a9e78f0.png\")
<\/figure>\n\n\n\nThe location of the Show Static Mesh property<\/p>\n\n\n\n
Then, if you ever toggle it off, you’ll see the object disappear, as follows:<\/p>\n\n\n\n
![\"\"\/](\"https:\/\/learning.oreilly.com\/library\/view\/unreal-engine-4x\/9781789809503\/assets\/340c8760-1eda-48ab-91fd-99f5034777b0.png\")
<\/figure>\n\n\n\nHow it works…<\/h1>\n\n\n\n
We create a new Actor based on StaticMeshActor for easy access to a visual representation via the Static Mesh.<\/p>\n\n\n\n
UPROPERTY is added to give us a property to change, which causes PostEditChangeProperty events to be triggered.<\/p>\n\n\n\n
PostEditChangeProperty is a virtual function that’s defined in Actor.<\/p>\n\n\n\n
As a result, we override the function in our class.<\/p>\n\n\n\n
Within our class constructor, we initialize our mesh as usual, and set the default state of our bool property to match the visibility of the component it controls.<\/p>\n\n\n\n
Inside PostEditChangeProperty, we first check that the property is valid.<\/p>\n\n\n\n
Assuming it is, we retrieve the name of the property using GetFName().<\/p>\n\n\n\n
FNames are stored internally by the engine as a table of unique values.<\/p>\n\n\n\n
Next, we need to use the GET_MEMBER_NAME_CHECKED macro. The macro takes a number of parameters.<\/p>\n\n\n\n
The first one is the name of the class to check, while the second parameter is the property to check the class for.<\/p>\n\n\n\n
The macro will, at compile-time, verify that the class contains the member specified by name.<\/p>\n\n\n\n
We compare the class member name that the macro returns against the name that our property contains.<\/p>\n\n\n\n
If they are the same, then we verify that our StaticMeshComponent is initialized correctly.<\/p>\n\n\n\n
If it is, we set its visibility to match the value of our ShowStaticMesh Boolean.<\/p>\n","protected":false},"excerpt":{"rendered":"
When a designer changes the properties of an\u00a0Actor\u00a0plac […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[27,1],"tags":[26],"_links":{"self":[{"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/posts\/3065"}],"collection":[{"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3065"}],"version-history":[{"count":2,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/posts\/3065\/revisions"}],"predecessor-version":[{"id":3349,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/posts\/3065\/revisions\/3349"}],"wp:attachment":[{"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3065"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3065"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3065"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- Implement PostEditChangeProperty:<\/li><\/ol>\n\n\n\n
- Create the class constructor by adding the following code to the PostEditChangePropertyActor.cpp file:<\/li><\/ol>\n\n\n\n
- Add the following UPROPERTY and function definition to the class:<\/li><\/ol>\n\n\n\n