效果图

shader
"varying highp vec2 textureCoordinate;\n" +
"\n" +
"uniform sampler2D inputImageTexture;\n" +
"\n" +
"void main()\n" +
"{\n" +
" lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);\n" +
" \n" +
" gl_FragColor = vec4((1.0 - textureColor.rgb), textureColor.w);\n" +
"}";
原理
颜色进行翻转