When having to develop a UE4 project that deals with a tiny world scale, like the whole level being less the 50cm size for example, The following steps may help make the project more easily navigate-able and convenient to work on.
Scale down the camera Icon: UE4 has by default a huge, bulky, opaque camera icon. For a tiny scale project, this camera icon may cover the whole level and be very inconvenient to work with. Select the relevant camera component and scale it down. In my tests, this modified camera matrix isn’t breaking the camera optics in any way, But if you want to have no such scale offsets in your project, you can also replace the camera icon with a suitable small one.
In Editor Preferences > Viewport: Decrease both: Mouse Scroll Camera Speed and Mouse Sensitivity To allow finer navigation at small scale
Note: A global scale conversion factor can be used instead of taking these measures, And in many cases this can be a more practical solution for managing a sub 50cm world, For example, building everything 100X size so that 1 meter will be representing 1 centimeter in your project’s world. But take into account, that if the project demands rendering realistic physical lighting and optics, extra conversions will have to be made to account for the scale conversion factor, so is such cases it may be better to setup a real-world scale project.
Note: This seems like an awkward workaround.. So if I missed something here, and there’s a better method to do this, I’ll be very grateful is you share it in the comments.
Replacing the camera icon: Its fairly simple to replace the Camera component’s mesh icon, Just select the component and replace it’s Camera Mesh Static Mesh component with a different static mesh object:
So what’s the problem? The problem is that the default mesh used for the camera icon doesn’t have its natural pivot at the focal point of the camera, but at its bottom somewhere, And there is a hardcoded transform offset that compensates for that and places the icon mesh in a way that has the Icon lens roughly at the actual Camera actor pivot / focal point:
* I haven’t found any exposed transform parameter that allows moving the icon itself without moving the camera. So in-order to replace the camera mesh with an alternative icon mesh, and have it be aligned properly to the camera’s pivot / focal point (without changing engine code and building it) the built-in offset must be negatively pre-added to the new mesh model:
In this example in Blender, a new icon is modeled facing positive Y, with pre-built offset to compensate for the hardcoded offset in UE.
An example of a simple fog effect created using a Post Process material:
The fog material Blueprint: The method for creating the fog effect is to take distance of the objects from the camera, map it to a value range suitable for color blending 0 – 1, and use that for blending the object’s color with the fog color, so the further away the object, the more it will be colored by the fog.
Start by creating a new material, and follow the details below to create the Blueprint:
The Material Domain is set to Post Process.
And has its Blendable Location parameter set to Before Tonemapping so it will be applied on the raw render.
A SceneTexture node with its Scene Texture Id parameter set to PostProcessInput0 serves as the input of the view’s original rendered pixel colors:
A Lerp (LinearInterpolate) node calculates the blending of the view’s original pixel colors with the Fog color to create the fog effect.
A SceneTexture node with its Scene Texture Id parameter set to SceneDepth serves as the input of depth of each pixel (distance from camera):
A ComponentMask node set to the R channel allows using the depth data as a single float value instead of a Vector4:
A Clamp node is used to clamp (limit) the depth value to the Fog’s maximum depth value (see below)
A RemapValueRange maps the distance value to a fog density value that will be used as the Lerp (3) alpha parameter.
Simply put, the further the object, the more the original color will be blended with the fog color.
A Power node (raises the fog blend factor by an exponent) make the fog blending non-linear, that is beginning gently for closer objects and than increasing more drastically as the distance grows (provided that the exponent value is above 1)
A Constant Vector4 serves as an input for the fog color.
* Note that having this input be a Vector4 and not a Vector3 allows it to be interpolated with the PostProcessInput0 data, otherwise a ComponentMask (RGB) node would have been necessary to convert the PostProcessInput0 to a Vector3.
a float constant serves as an input for the fog’s minimal distance (from camera)
a float constant serves as an input for the fog’s maximal distance (from camera)
* Note that it’s connected both to the Clamp node and to the RemapValueRange node.
a float constant serves as an input for the fog’s minimal opacity (blend amount)
a float constant serves as an input for the fog’s maximal opacity (blend amount)
a float constant serves as an input for the fog’s blend exponent.
Applying the Post Process material to the level:
Select the PostProcessVolume actor in the World Outliner window.
* Create a PostProcessVolume actor if necessary.
In the Details panel, under Rendering Features > Post Process materials,
Add a new item to the array, in the new item’s value choose Asset Reference,
And then select your fog material:
When Spawning new actors via the SpanActor Blueprint node, initial transform must be supplied to the SpanActor node, and not defined in the spawned Actor Class’s Blueprint.
Just found out the hard way, that when you spawn an Actor using the SpawnActor blueprint node, the transform data connected to the SpawnActor node is actually applied after the actors Construction Script and BeginPlay Event.
This means any transform you will try to apply in the spawned Actor’s Blueprint will be overridden and therefore not work.
Had some frustrating time not understanding why doesn’t the FirstPersonProjectile Actor doesn’t “play ball” and generate Overlap Events when hitting my bad guys..
It turns out I had to change its collision (sphere) component’s collision settings to overlap dynamic objects (see image):
By default UE4 uses fast simplified convex collision shapes to calculate collision for static mesh actors.
This means that the player or projectiles wont be able to path through holes, openings or doors in the model.
To set complex (concave) collision for a static mesh model:
In Static Mesh editing window, in the details pane, under Collision:
Set Collision Complexity to: Use Complex Collision As Simple
This example shows the default behavior for a model that has an opening, neither the projectiles nor the player can pass:
In this example collision for the model was set to Use Complex Collision As Simple:
UE4 Material Blueprint Numerical Vector Parameters / Constants and Colors are one and the same, which makes perfects sense, since in computer graphics colors are in fact 3D vectors, RGB quantities being equivalent to XYZ spatial dimensions (4D with an Alpha channel)
But take note that when setting the Vector values in the color picker you can’t set negative values, and when doing so through the Details window in Default Value you can.
* You can create 3D Vector Constants by clicking the background while pressing 3