This is Filter for https://github.com/kazukitanaka0611/GLCameraTemplate

CrosshatchFilterOpenGLView

@implementation CrosshatchFilterOpenGLView

#pragma mark -
- (NSString *)getFragmentShaderString
{
    NSString *const kFragmentShaderString = SHADER_STRING
    (
     varying highp vec2 textureCoordinate;

     uniform sampler2D inputImageTexture;

     uniform highp float crossHatchSpacing;
     uniform highp float lineWidth;

     const highp vec3 W = vec3(0.2125, 0.7154, 0.0721);

     void main()
     {
         highp float luminance = dot(texture2D(inputImageTexture, textureCoordinate).rgb, W);

         lowp vec4 colorToDisplay = vec4(1.0, 1.0, 1.0, 1.0);
         if (luminance < 1.00)
         {
             if (mod(textureCoordinate.x + textureCoordinate.y, crossHatchSpacing) <= lineWidth)
             {
                 colorToDisplay = vec4(0.0, 0.0, 0.0, 1.0);
             }
         }
         if (luminance < 0.75)
         {
             if (mod(textureCoordinate.x - textureCoordinate.y, crossHatchSpacing) <= lineWidth)
             {
                 colorToDisplay = vec4(0.0, 0.0, 0.0, 1.0);
             }
         }
         if (luminance < 0.50)
         {
             if (mod(textureCoordinate.x + textureCoordinate.y - (crossHatchSpacing / 2.0), crossHatchSpacing) <= lineWidth)
             {
                 colorToDisplay = vec4(0.0, 0.0, 0.0, 1.0);
             }
         }
         if (luminance < 0.3)
         {
             if (mod(textureCoordinate.x - textureCoordinate.y - (crossHatchSpacing / 2.0), crossHatchSpacing) <= lineWidth)
             {
                 colorToDisplay = vec4(0.0, 0.0, 0.0, 1.0);
             }
         }
         
         gl_FragColor = colorToDisplay;
     }
     );

    return kFragmentShaderString;
}

#pragma mark -
- (void)setUniform
{
    glUniform1f(glGetUniformLocation(self.programHandle, "crossHatchSpacing"), 0.01);
    glUniform1f(glGetUniformLocation(self.programHandle, "lineWidth"), 0.003);
}

@end