UISurfaceRaytraceInputHandler.cpp

/*****************************
 Copyright 2015 (c) Leonardo Malave. All rights reserved.
 
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#include "OculusUIPOC.h"
#include "Engine.h"
#include "UISurfaceRaytraceInputHandler.h"

UISurfaceRaytraceInputHandler::UISurfaceRaytraceInputHandler(ACharacter* Character, UCameraComponent* FirstPersonCamera)
{
    this->Character = Character;
    this->FirstPersonCameraComponent = FirstPersonCamera;
    SelectedUISurfaceActor = nullptr;
    RaytraceInputEnable = true;
    RaytraceUpOffset = -10.0;
    RaytraceForwardOffset = 50.0;
    RaytraceDistance = 4000.0;
    RaytraceDrawFraction = 0.75;
}

UISurfaceRaytraceInputHandler::~UISurfaceRaytraceInputHandler()
{
}

AUISurfaceActor* UISurfaceRaytraceInputHandler::GetSelectedUISurfaceActor() {
    return SelectedUISurfaceActor;
}

void UISurfaceRaytraceInputHandler::HandleRaytrace() {
    
    // Perform raytrace to get Hit result
    FVector StartTrace = FirstPersonCameraComponent->GetComponentLocation();
    FVector TraceDirection = FirstPersonCameraComponent->GetForwardVector();
    UWorld* World = Character->GetWorld();
    FVector EndTrace = StartTrace + TraceDirection * RaytraceDistance;
    
    FCollisionQueryParams TraceParams(FName(TEXT("LookTrace")), true, Character);
    TraceParams.bTraceAsyncScene = true;
    TraceParams.bReturnPhysicalMaterial = true;
    FHitResult Hit(ForceInit);
    World->LineTraceSingle(Hit, StartTrace, EndTrace, ECC_Visibility, TraceParams); // simple trace function
    
    // now check Hit result to see if it has hit a UISurfaceActor object
    AUISurfaceActor* UISurfaceActor = Cast<AUISurfaceActor>(Hit.GetActor());
    if (UISurfaceActor)
    {
        if (SelectedUISurfaceActor == nullptr) {
            SelectedUISurfaceActor = UISurfaceActor;
            SelectedUISurfaceActor->EnableInput(UGameplayStatics::GetPlayerController(World, 0));
        }
    }
    else { // if not targeting a UISurfaceActor, then reset flags on previously selected UISurface actor and null it out
        if (SelectedUISurfaceActor != nullptr) {
            SelectedUISurfaceActor->DisableInput(UGameplayStatics::GetPlayerController(World, 0));
            SelectedUISurfaceActor->ResetFlags();
            SelectedUISurfaceActor = nullptr;
        }
    }
    if (SelectedUISurfaceActor) {
        // Draw line and point if targeting a UISurfaceActor
        float ForwardOffset = RaytraceForwardOffset;
        float UpOffset = RaytraceUpOffset;
        float RaytraceLength = FVector::Dist(StartTrace,Hit.ImpactPoint);
        if (RaytraceLength < 100.f) {
            ForwardOffset = RaytraceLength * 0.5;
            UpOffset = (0.5 * RaytraceUpOffset) * (1 + RaytraceLength / 100.f);  // starts going from 100% to 50% of up offset
        }
        FVector LineStart = StartTrace + FirstPersonCameraComponent->GetUpVector() * RaytraceUpOffset + FirstPersonCameraComponent->GetForwardVector() * RaytraceForwardOffset;
        DrawDebugLine(World, LineStart, Hit.ImpactPoint, FColor::Blue.WithAlpha(50)); // NOTE:  DrawDebug methods are ignoring the Alpha
        if (!SelectedUISurfaceActor->PointerFingerIsHovering) {
            DrawDebugSphere(World, Hit.ImpactPoint, 0.5, 12, FColor::Blue.WithAlpha(50));
            UISurfaceActor->HandleMouseoverEventWorldLocation(Hit.ImpactPoint);
        }
    }
}