How to lighten color in shader program?

Question

I'm trying to achieve this look in my Unity Game:

I like how the color of the mountain gets lighter as the altitude increases.

I'm still new to game development and while I understand what shaders do, I'm having trouble trying to use them in practice.

I know I need to do something like this in my surface shader:

float4 mountainColor = lerp(_BottomColor,_TopColor,IN.vertex.z);

...to lerp between the darker color and lighter color based on the z value.

But I'm not sure how to pragmatically lighten a color in the shader. I'm not using vertex colors, the color comes from a texture. Any help/pointers would be appreciated.

EDIT:

So, duh, I realized I just have to multiply the rgb value to either lighten or darken it.

The issue is, if I just do something like this:

o.Albedo = c.rgb * 1.5;

... yes, it lightens it, but it also slightly changes the hue and becomes overly saturated.

How can I fix this?

Noah Roth · Accepted Answer · 2015-12-13 04:29:25Z

1

Here's my code:

Shader "Custom/Altitude Gradient" {
Properties {
    _Color ("Color", Color) = (1,1,1,1)
    _MainTex ("Albedo (RGB)", 2D) = "white" {}
    _Glossiness ("Smoothness", Range(0,1)) = 0.5
    _Metallic ("Metallic", Range(0,1)) = 0.0
}
SubShader {
    Tags { "RenderType"="Opaque" }
    LOD 200

    CGPROGRAM
    // Physically based Standard lighting model, and enable shadows on all light types
    #pragma surface surf Standard fullforwardshadows vertex:vert

    // Use shader model 3.0 target, to get nicer looking lighting
    #pragma target 3.0

    sampler2D _MainTex;

    struct Input {
        float2 uv_MainTex;
        float3 localPos;
    };

    half _Glossiness;
    half _Metallic;
    fixed4 _Color;

    void vert(inout appdata_full v, out Input o) {
        UNITY_INITIALIZE_OUTPUT(Input, o);
        o.localPos = v.vertex.xyz;
    }

    void surf (Input IN, inout SurfaceOutputStandard o) {
        // Albedo comes from a texture tinted by color
        fixed4 c = tex2D (_MainTex, IN.uv_MainTex) * _Color;
        o.Albedo = lerp(c.rgb * 0.5, 1, IN.localPos.y);
        // Metallic and smoothness come from slider variables
        o.Metallic = _Metallic;
        o.Smoothness = _Glossiness;
        o.Alpha = c.a;
    }
    ENDCG
}
FallBack "Diffuse"
}

It works good enough for my needs. I'll have to continue to fiddle with it to get the exact look I want, but the base is here.

edited Dec 13, 2015 at 4:29

answered Dec 12, 2015 at 22:19

Noah Roth

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2 Comments

AquaGeneral Over a year ago

Was this meant to be an answer to your own question? If not, it should be edited into your question instead.

Noah Roth Over a year ago

@AquaGeneral Yes, it's my answer.

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