Get Camera Edges From Frustum

Overview

This custom blueprint node retrieves the center of an orthographic camera's top, left, bottom and right frustum. It can be useful when you need to spawn actors right at the edge of the viewport.

Camera frustum visualized

Fire particle spawned at the center of each frustum. The cube represents the camera's location.

Usage

The node requires a CameraComponent as the input and outputs four FVectors, one for each frustum center.

To get this node inside the project copy the following files to your C++ classes directory.

CameraUtils.h

#pragma once

#include "Camera/CameraActor.h"
#include "CameraUtils.generated.h"

/**
 * 
 */
UCLASS()
class PROJECTNAME_API ACameraUtils : public ACameraActor
{
    GENERATED_BODY()

public:

    UFUNCTION(BlueprintPure,
        meta = (
            DisplayName = "Get Camera Edges from Frustum",
            Keywords = "Camera Edges Frustum"
            ),
        Category = "Camera|Utility")
        static void GetCameraFrustumEdges(UCameraComponent* camera, FVector& topCenter, FVector& leftCenter, FVector& bottomCenter, FVector& rightCenter);

};

CameraUtils.cpp

Note: Don't forget to change ProjectName.h to whatever your project is named

#include "ProjectName.h"
#include "CameraUtils.h"

void ACameraUtils::GetCameraFrustumEdges(UCameraComponent* camera, FVector& topCenter, FVector& leftCenter, FVector& bottomCenter, FVector& rightCenter)
{
    // Assumptions: Camera is orthographic, Z axis is upwards, Y axis is right, X is forward

    FMinimalViewInfo cameraView;
    camera->GetCameraView(0.0f, cameraView);

    float width = cameraView.OrthoWidth;
    float height = width / cameraView.AspectRatio;

    topCenter.Set(cameraView.Location.X,
                  cameraView.Location.Y,
                  cameraView.Location.Z + height/2.0f);

    bottomCenter.Set(cameraView.Location.X,
                     cameraView.Location.Y,
                     cameraView.Location.Z - height / 2.0f);

    leftCenter.Set(cameraView.Location.X,
                   cameraView.Location.Y - width / 2.0f,
                   cameraView.Location.Z);

    rightCenter.Set(cameraView.Location.X,
                    cameraView.Location.Y + width / 2.0f,
                    cameraView.Location.Z);

}