Black and White Shader (GPUImage)

blackandWhite.fsh

precision highp float;

varying highp vec2 textureCoordinate;
uniform sampler2D inputImageTexture;

void main()
{
    highp vec4 textureColor;
    highp vec4 rCol;
    highp vec4 gCol;
    highp vec4 bCol;
    highp vec4 outputColor;

    
    textureColor = texture2D(inputImageTexture, textureCoordinate);
    rCol = vec4(vec3(textureColor.r), 1.0);

    
    textureColor = texture2D(inputImageTexture, textureCoordinate);
    gCol = vec4(vec3(textureColor.g), 1.0);

    
    textureColor = texture2D(inputImageTexture, textureCoordinate);
    bCol = vec4(vec3(textureColor.b), 1.0);
    
    float avgColorVal = (rCol.r+gCol.g+bCol.b)/3.0;
    gl_FragColor = vec4(vec3(avgColorVal,avgColorVal,avgColorVal),1.0);
}