dFdyCustom.shader

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Shader "Custom/dFdyCustom" {
   Properties
    {        
            _MainTex ("Texture Image", 2D) = "white" {}
            _TexSizeY ("Texture Height", Float) = 0.0
    }
    SubShader
    {
        Pass
            {            
                GLSLPROGRAM
                
                uniform sampler2D _MainTex;
                uniform float _TexSizeY;
                
                varying vec4 textureCoordinates; 
                                       
                #ifdef VERTEX   
                
                void main()
                {          
                   textureCoordinates = gl_MultiTexCoord0;
                    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
                }
                #endif  
           
                #ifdef FRAGMENT
                void main()
                {
                   vec4 c0 = texture2D(_MainTex, vec2(textureCoordinates) + vec2(0.0, -1.0/_TexSizeY));
                   vec4 c1 = texture2D(_MainTex, vec2(textureCoordinates) + vec2(0.0, 1.0/_TexSizeY));
               
                   vec4 g = (c1 - c0) / 2.0;

                   float gradient = (g.r + g.g + g.b) / 3.0;

                   gradient = (gradient + 1.0) / 2.0;

                   gl_FragColor = vec4(gradient, gradient, gradient, 1.0);
                }
                #endif                          
                ENDGLSL        
            }
   }
}