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
    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,
            s,c,0,0,
            0,0,1,0,
            0,0,0,1);
     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*/v.vertex.xyz += ConvertToDir(v.color.xyz) * 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(v.color.xyz)' 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

Comments

  1. I needed to thank you for this incredible read!! I unquestionably adored each and every piece of it. I have you bookmarked your site to look at the new stuff you post. share more details.
    Ai & Artificial Intelligence Course in Chennai
    PHP Training in Chennai
    Ethical Hacking Course in Chennai Blue Prism Training in Chennai
    UiPath Training in Chennai

    ReplyDelete

Post a comment

Assets Worth Checking Out

POPULAR POSTS

Curved Surface Shader [ Unity Implementation ]

Curved Surface Shader This is the shader that we will be having at the end of this tutorial.
 The curved surface shader is capable of achieving really varied visual effects from showing space-time curve due to gravity to a generic curved world shader that is seen in endless runners like Subway Surfers.
The concepts that you learn here can open you up to a new way of looking at shaders and if you didn't think they were the coolest thing ever already, hopefully let this be the turning point.😝.

Both the examples show above use the same exact material is just that different values have been passed to the shader.
Start by creating a new unlit shader in Unity and we will work our way from there.
First we define what the properties are:
_MainTex("Texture", 2D) = "white" {} _BendAmount("Bend Amount", Vector) = (1,1,1,1) _BendOrigin("Bend Origin", Vector) = (0,0,0,0) _BendFallOff("Bend Falloff", float) = 1.0 _BendFallOffStr("Falloff s…

Introduction To Replacement Shaders & Shader Keywords

What is a replacement shader? A replacement shader is a shader that gets applied to every object being rendered.
Since the camera determines what objects end up being shown on screen, The functionality for setting up replacement shaders are in the camera class as well.

A good use case of a replacement shader would be in making effects like SSAO.
Here we need access to the normals and the depth information so a replacement shader that displays only the normals can be rendered ( stored in a render texture ) and then another shader that displays the depth information ( stored in a render texture ) and then the final image is rendered with the SSAO effect by taking the two render textures as input and doing a bunch of calculations.

Another use case would be to visualize the environment differently for various reasons like how they did in City Skylines.

The function that performs shader replacement is:
Camera.SetReplacementShader( Shader shader, string replacementTag ) Takes in a shader as …

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…

Access Reflection Probe Data For Custom Shaders

The Unity shader documentation regarding reflection probes is pretty minimal and not at all comprehensive.
This short tutorial is intended to bring reflection probe functionalities to the forefront your future shader writing endevors which is a fancy way of saying "Look at this cool stuff and go and use it somewhere" 😏
Here we will try just the bare minimum of making a shader that reflects the cubemap data from reflection probe and displays it on the object.

These reflection probes are basically objects that store a complete image of the environment surrounding it into a cubemap which then can be read by shaders to create various effects.
More information on how reflection probes work in Unity can be found here :
Using Reflection Probes In Unity

I am not going over how to set up Reflection Probes here only how to access them inside our custom shaders.
So this is what we will be making:
The reflection probe takes in the cubemap only if it is within it's range otherwise i…

How To Animate A Fish Swimming With Shaders

Animate Fish Swimming With Shaders We are going to make swimming animation by using only shader code.
By the time we are done, it's going to look like this.
You will probably need the fish model used in this tutorial, that can be found HERE. Can use your own model but the shader code might have to be modified accordingly because of the orientation of the model that you might be using ( issues with whether the X axis & Z axis is flipped ).
The shader used way out performs a similar scene with skeletal animations applied on the fish models.
On a previous benchmark I did comparing the shader animation with the skeletal animation there was a difference of 28 FPS( on average ) with 50 fish.
The shader we are going to make is really powerful and flexible and don't think that it's limited to making fishes swim😀.


So this mesh oriented like this when imported into unity and this is important to understand because this means that the model's vertices have to be moved along the X-…