Skip to main content

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:
reflection probe shader
A sphere with a reflection probe affecting it
The reflection probe takes in the cubemap only if it is within it's range otherwise it will use the default skybox cubemap.
You might have also noticed that I'm also able to change the sharpness of the image and make it more or less blurred, This is basically what roughness does in the Unity standard shader.
We will utilize a cool capability of the cubemap which allows us to do the roughness effect as well.

As usual, we will take each section of our shader and explain it.
First, we will look at the properties:
Properties
{
 _Roughness("Roughness", Range(0.0, 10.0)) = 0.0
}
Let's look at our definitions within the CG PROGRAM
float _Roughness;

struct appdata
{
 float4 vertex : POSITION;
 float3 normal : NORMAL;
};

struct v2f 
{
        float3 worldPos : TEXCOORD0;
        float3 worldNormal : TEXCOORD1;
        float4 pos : SV_POSITION;
};
Now the vertex shader:
v2f vert (appdata v)
{
        v2f o;
        o.pos = UnityObjectToClipPos(v.vertex);
        o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
        o.worldNormal = UnityObjectToWorldNormal(v.normal); // From local space normals to world-space normals
        return o;
}
Nothing complicated happened in the vertex shader.
Now the fragment shader:
fixed4 frag (v2f i) : SV_Target
{
         half3 worldViewDir = normalize(UnityWorldSpaceViewDir(i.worldPos)); //Direction of ray from the camera towards the object surface
         half3 reflection = reflect(-worldViewDir, i.worldNormal); // Direction of ray after hitting the surface of object
         /*If Roughness feature is not needed : UNITY_SAMPLE_TEXCUBE(unity_SpecCube0, reflection) can be used instead.
         It chooses the correct LOD value based on camera distance*/
         half4 skyData = UNITY_SAMPLE_TEXCUBE_LOD(unity_SpecCube0, reflection, _Roughness); //UNITY_SAMPLE_TEXCUBE_LOD('cubemap', 'sample coordinate', 'map-map level')
         half3 skyColor = DecodeHDR (skyData, unity_SpecCube0_HDR); // This is done because the cubemap is stored HDR
         return half4(skyColor, 1.0);
}
The cubemap has Tri-linear mapping applied on it which allows smooth transitions between LOD mip-map levels.
Here we are taking the mip-map level as the roughness value.
Higher mip-map levels correspond to a higher roughness of the material.

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

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…

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-…