Skip to main content

Noise Generation Algorithms : Voronoi - Part 1


What is Voronoi ?

You may have heard of Voronoi noise if you have worked with software like blender or substance painter. It's really good way of making surfaces that look like they have sharp creases enclosing a smooth surface.
Usually used to make hardened lava flows, parched ground as well as more organic looking structures like skin and animal hide, living cells.
In this part we will see how to create a Voronoi pattern in Unity and how to set your own points in the shader itself to create the Voronoi pattern.
We will go over the 'Noise' part of Voronoi noise in Part 2.
The basic element that the Voronoi pattern depends is the 'Distance Field' function.
Take the case where there are 'N' points and we have to find the distance field of those points,
We have to calculate the distance between each pixel and the point closest to it.
This is what we will end up having in this tutorial:
Voronoi Pattern Made With Given Points
We will be creating a script that passes a set of Vector2s to a shader which in turn draws it.
Before we get to C# scripting, we will see how to make the shader.
First of all we don't have any properties for this shader.😋. We will have properties in the coming parts.
But we do have a global variable called 'float2 _points[5]' - This can be accessed through C# code.
Let's look the two structs that we have:
float2 _points[5];
struct appdata
{
 float4 vertex : POSITION;
 float2 uv : TEXCOORD0;
};

struct v2f
{
 float2 uv : TEXCOORD0;
 float4 vertex : SV_POSITION;
};
No fancy-pancy stuff.
Now the vertex shader:
v2f vert (appdata v)
{
 v2f o;
 o.vertex = UnityObjectToClipPos(v.vertex);
 o.uv = v.uv;
 return o;
}
Nothing special here either. Now the fragment shader:
fixed4 frag (v2f i) : SV_Target
{
 fixed4 col = fixed4(0,0,0,1);
 float minDist = 1.0;
 float2 coord = i.uv;
 for (int i = 0; i < 5; i++) 
 {
  float dist = distance(coord, _points[i]);  
  minDist = min(minDist, dist);
 }
 col += minDist;
 return col;
}
We will see all the important parts and break it down.
for (int i = 0; i < 5; i++) 
{
 float dist = distance(coord, _points[i]);  
 minDist = min(minDist, dist);
}
Here we are iterating through all the points and keeping the minimum distance value in minDist.
Then after that we are just adding that as the colour of the pixel.
So we essentially just drew the distance field of those points.
What we have to do now... is that we have to access those points by C# code.
So the Unity API provides us a way to do so, with the Material.SetVectorArray function.
So here is the C# code:
using UnityEngine;
public class VoronoiNoise : MonoBehaviour
{
    public Material mat;
    public List<Vector2> points;

    void Update ()
    {
        if(points.Count == 5)
            mat.SetVectorArray("_points", ConvertToVec4(points));
    }

    List<Vector4> ConvertToVec4(List<Vector2> vec2)
    {
        List<Vector4> vec4 = new List<Vector4>();
        for (int i = 0; i < vec2.Count; i++)
            vec4.Add(new Vector4(vec2[i].x, vec2[i].y, 0, 0));
        return vec4;
    }
}
For ease of use in Editor I have used Vector2s as member variables and then later convert them to Vector4s before passing to the function. SetVectorArray only takes in List of Vector4s.
Now you can play around with it.. till your heart's content. 
Move onto Part2 where we will do even cooler stuff and actually do Voronoi noise instead of just making a pattern with out inputs.
If you like programming shaders make sure you check these out : Shader Tutorials
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. 

Comments

Assets Worth Checking Out

POPULAR POSTS

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 (…

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...…

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…

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…