The ability to create realistic materials using the Eevee render engine is a little more challenging than in the Cycles engine, considering Eevee is primarily built for speed. A very popular material to learn that is also a great exercise is to create a hologram material, which applies several key material attributes, like emission and transparency.
To create a hologram material in Eevee, delete the principled shader for your material and replace it with a mix of transparent and emission shaders. Use the Fresnel node as the factor for the two attributes to create the hologram look. You will also need to change the blend mode of the material to Alpha Hashed to view transparency in Eevee.
Like any material you can use any number of node combinations to create your desired effect, but the foundation of those three shader nodes is important to create that hologram appearance.
How To Set Up Transparency In The Eevee Render Engine?
The first step is to prep your Eevee engine work with both transparency and emission. While Cycles is designed to create realistic scenes using ray-traced methods, Eevee uses more traditional rasterized methods of faking realism. This is true for both emission and transparency.
To create the bloom effect that emissive materials generate, go to the render tab in the properties panel and enable the setting for bloom. While you are here, turn on any of the other features that you wish to use, but the bloom is the main one for us right now.
For best results in the viewport, go to the world tab in the properties panel and lower the world brightness down to 0, although you may wish to delay this until the material has been added to the object.
With the bloom ready, go to the material tab in the properties panel and add new material to your model if one has not already been added.
Scroll down to the bottom of the material options where you will find the settings section. Open this up and change your blend mode to alpha hashed to enable the transparent channel for the material.
Why Choose Alpha Hashed For The Blend Mode?
By default, the opaque option is selected here meaning that objects do not display the alpha channel at all. It’s basically the offsetting for transparency in Eevee.
You do have three other options for enabling transparency though when you access the menu for the blend mode. These are alpha clip, alpha hashed, and alpha blend.
So why choose alpha hashed specifically? The alpha clip option acts sort of like a boolean. If a property of your material reaches a specific value defined by the clip threshold, then the model becomes transparent and is either fully transparent or not at all.
For the material that we create for our hologram. We use a mix shader to combine transparency with emission, and the factor controls which shader is favoured. If the clip threshold is 0.5, and the factor value is 0.4, then the object will be transparent because it favors the transparent shader in the first slot.
Alternatively, if the mix factor is above the clip threshold then transparency is not applied and instead, the object is fully emissive.
On the other hand we have the alpha blend option which uses the data from the alpha channels to determine the visibility. With this option, the mix slider behaves as required but if looking through your object to another piece, that piece will not appear transparent. For example, look through one side of Suzanne and the ear on the other side will not be transparent.
This option is also too smooth for what you would expect from a typical hologram which if you watch sci-fi films appears slightly noisy.
That’s why we use the alpha hashed option, which applies low-level noise to the transparency to give it that rougher appearance especially when moving the camera.
The Base Setup For Any Hologram Material In Eevee
When you have set up Blender to use both bloom and alpha, go to the shading workspace where you can view the node tree for your material.
The first thing that we need to do is delete the principled shader, as our material does not require most of the options that it provides. So select the principled shader and then delete it.
We will replace one shader with three now. The first shader to add will be the mix shader, so connect this shader directly to the material output.
Next, add a transparent shader and it to the first shader slot in the mix shader. Then add an emission shader to the second shader input.
If you change your view to rendered view, you will see your material in effect. Adjusting the mix sliders factor value controls if you want to prioritize transparency with a lower value or emission with a higher value.
Changing the emissive color will alter the color of the material, since that’s the shader that is visible to us. Adjust the bloom settings to either increase or decrease the bloom effect in the properties panel.
Controling The Factor With Fresnel
This is a very simple setup that gives us the basic material properties of a hologram. But we can go much further than this and really create something special.
One trick is to control where the model is transparent and where light is projected using a fresnel node. If we add the fresnel node to our setup and connect it to the factor of the mix shader, we can use the IOR value to control how much of the model emits light from the angles of the surface.
Basically, a value close to 1 keeps the emission close to the areas of the surface that are viewed from an angle, meaning more of the object is transparent.
By contrast, a value further away from 1 will push the emissive light further toward the center of the model.
An alternative here is to use the layer weight node and then use the facing output, adjusting the blend value to determine the area of the emission.
The result of this may be preferable to the fresnel node as while transparency is maintained the object’s shape is more visible using the facing output of this node than just using the fresnel.
Using Texture Nodes Instead Of The Fresnel Node For Material Data
The fresnel node allows you to create an effect where the angles of the model dictate its visibility, nut what if you wanted to take things further. What if you want to create a wave pattern for your style of the hologram.
This is possible thanks to the use of the various procedural textures in Blender. We can use these image textures in place of our fresnel node to control the factor of the material.
For example, the wave texture will allow us to create the lined effect on the hologram. We simply need to add it to the mix shaders factor value and adjust the settings to what we need.
In this image, the wave pattern follows the Z-axis and the scale is increased so that we get lots of smaller lines. Different textures will allow us to create different patterns on our material.
If we want to create a similar wave effect, but not have the lines go all the way around the model, then we can try the brick texture instead.
If we wanted to create an effect where the emission is stronger towards the top of the object, then we could use a gradient texture and combine it with a mapping node to rotate the gradient to the Z-axis.
For this setup, you can see that the color ramp is used after the gradient texture to add more control to both the transparent and emissive properties, as without it the bottom area of the model would be fully transparent, so the black on the color ramp is made lighter to make the bottom half visible.
The possibilities are endless, and you can even use an image texture like adding the world map to a sphere and creating a hologram of the world.
Thanks For Reading The Article
We appreciate you taking the time to read through the article and we hope that you found the information that you were looking for. Take a look at some of the other articles surrounding this topic area.
- 8 Ways To Use The Node Wrangler
- How To Apply Transparency In The Eevee Render Engine For Glass
- Repeating A Texture Pattern On A Surface Without Visible Seams
- The Clearcoat Attribute In Blender Materials
- Overlay A Decal Texture On Your Objects With Transparency
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