uniform lowp sampler2D u_texture0; uniform lowp vec2 threshold; varying vec2 v_texCoords; void main(){ vec4 color = texture2D(u_texture0, v_texCoords); if(color.r + color.g + color.b > 0.5 * 3.0){ gl_FragColor = color; }else{ gl_FragColor = vec4(0.0); } //gl_FragColor = (texture2D(u_texture0, v_texCoords) - vec4(threshold.r)) * threshold.g; }