Skip to main content

Fortnite Procedural Construction Animation Shader

Fortnite Construction Shader

This shader is loosely based on the one that was presented by the Fortnite developers in their GDC talk: Inner Working Of Fortnite's Shader-Based Procedural Animations.

 Here is what we will end up with:
Fortnite building shader
This technique requires you to author the 3D model in a certain way, More or less how those Fortnite developers did.
So we need the authored 3D model and the shader that uses data we get from the model to achieve the desired effect.

There are some nuances here and there so make sure you don't miss out on the details.😗
The first step will be preparing the 3D model and putting in the required data. I used Blender 2.79 but any 3D modeling software would do.

3D Model Preparation

  1. Model It
    3d mesh
  2. Apply Vertex Colors: For the direction of flight
    Each color is a component of a vector (x, y, z). This will be considered as local space.
    Values range from -1.0 to +1.0 for each component.
    Negative values are achieved by using values of less than 0.5 and positive values with values greater than 0.5.
    Assume 'val' : Range from 0.0 - 1.0
    You can use your own mapping such as '(val - 0.5) * 2'.
    • Gives -1.0 if val was 0.0
    • Gives +1.0 if val was 1.0
    • Gives 0.0 if val was 0.5
    • Gives 0.5 if val was 0.75
    • Gives -0.5 if val was 0.25
    Basically :
    (0.0 , 0.5) maps to (-1.0 , 0.0)
    (0.5 , 1.0) maps to (0.0 , 1.0)
    The mapping I've used :
    • Gives 0.0 if val was 0.5
    • Gives +1.0 if val was 1.0
    • Gives 0.0 if val was 0.0
    • Gives 0.5 if val was 0.75
    • Gives -0.5 if val was 0.25
    • Gives -1.0 if val was 0.4999 (less than 0.5 but tending towards it)
    Basically :
    (0.0 , 0.5) maps to (0.0 , -1.0)
    (0.5 , 1.0) maps to (0.0 , 1.0)
    vertex colors
  3. UV Channel 1: For applying timing textures and rotation amount.
    The UV map is difficult to see, I suggest zooming in. Those dots placed are each of the separate vertex sections that make up the mesh.
    Shown here : Red channel = x position of UV & Green channel = y position of UV
    • The greater the UV's x coordinate of a vertex the later movement of the vertices will start ( assuming the initial stage was having all pieces together )
    • The greater the UV's y co-ordinate the more rotations about the local z-axis it will do.
    First UV Channel data for mesh
  4. UV Channel 2: Actual texture map.
    The texture used can be found here: Pexels - Antique Backdrop
    textured mesh

Fortnite Construction Surface Shader

We will be using a surface shader as our base. So go ahead and create one.
  1. Defining Our Properties
     _Color ("Color", Color) = (1,1,1,1)
     [HideInInspector]_MainTex("Main texture", 2D) = "white"{}
     _ActualTex("Actual Texture", 2D) = "white"{}
     _Glossiness ("Smoothness", Range(0,1)) = 0.5
     _Metallic ("Metallic", Range(0,1)) = 0.0
     _Placement("Placement value", Range(-0.0, 100.0)) = 0.0
    We don't actually end up using _MainTex in our shader, But we need to declare it here due to quirks of using a secondary UV channel.
    Since we don't end up using it we can hide it in the inspector with [HideInInspector] attribute.
  2. Input Struct & CG Declarations
    sampler2D _ActualTex;
    sampler2D _MainTex;
    half _Glossiness;
    half _Metallic;
    fixed4 _Color;
    float _Placement;
    struct Input 
     float2 uv_MainTex; // UV co-ordinates for our timing & rotation about z-axis
     float2 uv2_ActualTex; // 2nd UV co-ordinate used for the actual texturing purposes
     float4 color : COLOR; // Vertex color
  3. Helper Functions
    float3 ConvertToDir(float3 val)
     val.x = lerp(-val.x * 2, (val.x - 0.5) * 2, step(0.5, val.x));
     val.y = lerp(-val.y * 2, (val.y - 0.5) * 2, step(0.5, val.y));
     val.z = lerp(-val.z * 2, (val.z - 0.5) * 2, step(0.5, val.z));
     //In case it's not clear, With a conditional statement : val.z = (val.z < 0.5)? -val.z * 0.5 : (val.z -0.5) * 2;
     //Alternative mapping : val.z = (val.z - 0.5) * 0.5;
     val = normalize(val);
     return val;
    float4 RotateAroundZInDegrees (float4 vertex, float degrees)
            //Creating a rotation matrix to multiply with our vertex position
     float angle = radians(degrees);
     float c = cos(angle);
     float s = sin(angle);
     float4x4 rotateZMatrix = float4x4(c,-s,0,0,
     return mul(vertex , rotateZMatrix);
  4. The Vertex Shader
    void vert (inout appdata_full v) 
     /*1*/float val = max((_Placement - v.texcoord.x * 100), 0);
     /*2*/v.vertex = RotateAroundZInDegrees(v.vertex, val * v.texcoord.y * 100);
     /*3*/ += ConvertToDir( * val;
    *Note: The _Placement value is the value that determines where our vertices end up.
    v.texcoord.x:- Timing value, Determines when the movement of the vertices for that vertex starts. (Range : 0.0 - 1.0)
    v.texcoord.y:- The amount of rotation to be applied. (Range : 0.0 - 1.0)
    1. When _Placement value crosses the threshold value set by (v.texcoord.x * 100) only then the vertex moves.
    2. The lower the value of 'val' less the rotation applied on the vertex.
    3. The 'ConvertToDir(' function takes in vertex color and converts that into a direction for the vertex to move. Then we multiply with 'val' thereby determining the distance the vertex moves in that direction.
  5. The Surface Shader
    void surf (Input IN, inout SurfaceOutputStandard o) 
     fixed4 c = tex2D (_ActualTex, IN.uv2_ActualTex) * _Color;
     o.Albedo = c.rgb;
     o.Metallic = _Metallic;
     o.Smoothness = _Glossiness;
     o.Alpha = c.a;
    Nothing mystical happening here. Sampling our texture with the correct texture map and UV coordinates.
  6. Vertex Shader Declaration And Shadow Pass
    #pragma surface surf Standard fullforwardshadows vertex:vert addshadow
    We need to declare our vertex function with 'vertex:vert' since our vertex function is called 'vert'.
    We are modifying our vertices so the shadows won't look correct as it's using Unity's default shadow pass, So we need to tell Unity to use a custom shadow pass which takes into consideration those new vertex positions; To do this 'addshadow' is used in our #pragma.
That's it! Hope you learned something.
Support Bitshift Programmer by leaving a like on Bitshift Programmer Facebook Page and be updated as soon as there is a new blog post.
If you have any questions that you might have about shaders or unity development in general, don't be shy and leave a message on my facebook page or down in the comments.
For the Unity-Package, go HERE.
For the entire source code, go HERE.
For more Shader development tutorials, go: HERE
For Unity development tutorials, go: HERE


Assets Worth Checking Out


Shader Optimization Part 1

The process of shader optimization can seem like trial and error... in fact, that's how it is most of the time.
Most of the time shader optimizations could be boiled down to educated guesses because each time a shader gets compiled, the GPU driver of that specific hardware is what converts your code into actual machine code, therefore, the machine code generated will be different for each GPU and the driver itself might perform some optimizations on top of your's which won't be available on another GPU, thereby making it difficult to have a standard way of writing optimal shader code.

So the best way to know for sure is to actually test it on the hardware you are targeting.
With that said, Here are some universal best ways of getting your shader to perform better.😅 Do Calculations On Vertex Shader The most commonly used case for this is lighting, an example would be Gouraud lighting, where lighting calculations are done per vertex but at the loss of quality.

Some calculatio…

Toon Liquid Shader - Unity Shader

Toon Liquid Shader This is how the shader will end up looking :
This shader is pretty neat and somewhat easy to implement as well as to understand. Since we will be adding some basic physics to the toon water as it is moved about we will have to support that in the vertex shader as well.
So let's start by looking at the properties :
Properties { _Colour ("Colour", Color) = (1,1,1,1) _FillAmount ("Fill Amount", Range(-10,10)) = 0.0 [HideInInspector] _WobbleX ("WobbleX", Range(-1,1)) = 0.0 [HideInInspector] _WobbleZ ("WobbleZ", Range(-1,1)) = 0.0 _TopColor ("Top Color", Color) = (1,1,1,1) _FoamColor ("Foam Line Color", Color) = (1,1,1,1) _Rim ("Foam Line Width", Range(0,0.1)) = 0.0 _RimColor ("Rim Color", Color) = (1,1,1,1) _RimPower ("Rim Power", Range(0,10)) = 0.0 } Just the usual stuff that we are used to. The only thing that may stand out is the [HideInInspector] tag, This works j…

Alto's Adventure Style Procedural Surface Generation Part 1

Alto's Adventure Style - Procedural Surface Generation This game appears to be a strictly 2D game but if you have played it enough you will notice that some of the art assets used look like it's 3D ( I don't know if they are tho ). If you haven't played the game you are missing out on one the most visually pleasing and calming games out there ( There is literally a mode called Zen mode in the game ).
Anyway, I am going to show you how to make a procedural 2D world ( without the trees, buildings and background ) like in Alto's Adventure.
But you may notice I have a plane which is in in the Z-axis giving a depth to the surface which is not there in Alto's Adventure but if you want to know how to do it then that will be in part 2.
To achieve the same effect of Alto's Adventure ( I'm leaving that up to you ) only minimal changes are needed to the code that I am going to explain.
We are going to be using the plane mesh in unity for creating the 2D surface as th…

Gift Wrapping Convex Hull Algorithm With Unity Implementation

Convex Hull Algorithm Convex Hull algorithms are one of those algorithms that keep popping up from time to time in seemingly unrelated fields from big data to image processing to collision detection in physics engines, It seems to be all over the place. Why should you care? Cus you can do magic with it and it seems so simple to implement when you first hear about it, but when you start thinking about it, you will realize why it's not such a straightforward thing to do.
Now that I got you interested (hopefully) and now we will see just what a convex hull is.
As you may have noticed a perimeter was made with the same points that was given and these perimeter points enclose the entire set of points.
Now we have to clear up the term 'Convex'.
Convex means no part of the object is caved inwards or that none of the internal angles made by the points exceed 180 degrees.
In this example of a concave shape internal angles go beyond 180 degrees.
What are those red lines for? Well...…

Pixelation Shader - Unity Shader

Pixelation Shader This is the correct way (one of many) of showing pixelation as a post-processing effect. This effect will work in any aspect ratio without any pixel size scaling issues as well as it is very minimal in terms of coding it up.

In order to get this to work 2 components have to be set up:
1) The pixelation image effect
2) The script - which will be attached to the camera

So let's get started by creating a new image effect shader.
We will take a look at our Shaderlab properties :
_MainTex("Texture", 2D) = "white" {} That's it, Everything else will be private and not shown in the editor.
Now we will see what are defined along with the _MainTex but are private.
sampler2D _MainTex; int _PixelDensity; float2 _AspectRatioMultiplier; We will pass _PixelDensity & _AspectRatioMultiplier values from the script.
As this is an image effect there is no need to play around with the vertex shader.
Let's take a look at our fragment shader:
fixed4 frag (…