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Unreal Engine 4 : Part 6 - Light management

Par Fayçal SIDI ALI MEBAREK Publié le 26/08/2019 à 16:10:49 Noter cet article:
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We have seen in the previous parts, how the Unreal Engine evolved to reach version 4 today. We downloaded it on our machine, learned how to use the Epic Games Launcher and how to create his project with some basic notions.

We will now continue to move forward, this time with more complex and indispensable notions. Here, it will concern the light management in our project. We had already placed a "Point Light" in our universe in part 5. Now, we will go further.

Different types of light

At the top left of the Unreal Engine window, you have the "Modes" tab; we have access here to different sections, including "Lights", the one we are interested in; we will click on it to see the content.

So there are different types of lights, each with different effects. Here they are:

  • Directional Light : It is a light far away from your scene, even from the outside, such as the rays of the sun, or the illumination of the moon on your world for example.

  • Point Light: It is a light emitted in all directions from a point (as its name suggests). This time, it is a light on your property. It could be compared to a lamp or a bulb.

  • Spot Light: It also emits a light from a point, as for "Point Light". The difference is that the light is emitted in the form of cones with angles that we can modify to have the desired effect. So it's like a spot of light like for a concert for example.

  • Sky Light: It is a question of simulating the light that the sky reflects. So for example adding clouds will visually modify the lights in the created world.

These different lights all have different effects and roles. Of course, it is the use of these different lights that will have a real effect on your work. It is therefore an extremely meticulous work that requires extreme precision if you want to make your creation immersive.

We have already seen how to add a Point Light; now we will place a Spot Light for testing.

Adding a Spot Light

First we will create a scene that looks from a distance like a show or concert scene... We will add cubes in the field and adjust them as on the screen below:

First of all, to make the platform from the bottom of the cube and lights, just take a cube and stretch it by changing its scale, then place the cubes over it to make it look like a show scene. To add cubes, you can select one, then copy and paste it and move the new cube. To change the scale or rotation of an object, use space to switch from rotation mode to scale mode. We then place the spotlights above the cubes to observe the effects of light with shadows. To place the spotlights, just drag and drop them again; then move them as on the screen for example (you can test them as you like, because it's just an example you can rely on). Here, we have placed 3 of them along the scene. To see what this affects, the intensity of the light has been set to 5000, and with a blue color; and the rotation has been modified as above, oriented towards the cubes. This is the effect that a spot light can have.

We will now see in the detail tab on the right of the screen, and explain what can be done.

Content of the "Details" tab

To see the details of the spotlight object we have placed, you must select it and see on the right of the screen, the "Details" tab. This applies to any other object. We'll see what's in this tab:

The "Transform" tab

This tab is often the same for almost all objects, because it is basic information, such as the location of the object, its size...

  • Location: by modifying this option, we modify the location of the object in the level. When you move the object with the mouse, the engine automatically changes the values, but it is sometimes useful to do it by hand to make it as accurate as you want. The 3 values to be modified are therefore the coordinates X, Y and Z of the object.

  • Rotation: This is the data that allows you to rotate your object in the angles you want, from 0° to 360°.

  • Scale: It is the size of the object, it is possible to enlarge it from the X axis, therefore on the horizontal; from the Y axis on the vertical, and Z for the height.

  • Mobility: This is the way light works. If it is static, It is a light that cannot move in the game and where the player cannot interact with it; stationnary, a light that cannot move but the player can interact with it by changing the color, for example; and movable, which is a dynamic light, which can be modified and moved in the game (it is necessarily the most resource-hungry light).

The "Light" tab

This tab concerns precisely the light we have placed, these parameters do not concern the cubes for example... It is a question of modifying the power of its radiation, its color, and its radius:

  • Intensity: This is the power of your light; by increasing it, the light will be stronger.

  • Light Color: The color of your light.

  • Radius Attenuation: This is the range of light. The higher the value, the further it will illuminate.

  • Inner Cone Angle / Outer Cone Angle: By changing these settings, you change the angles of light emission.

By playing with this, we get the result of the screen below:

Conclusion

We learned the basics of the Unreal Engine 4 engine, from the creation of its project, to the modification of parameters essential for its development, knowing how to place, adjust and modify the different lights, to make your project as immersive as possible. You can train and test the different parameters to see what they affect.

Next part, we will modify our different objects to give the illusion of a building.

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