How to make LabelBMFont blur with GLSL?

cocos2d-x C++
#1

I have learned how to make Sprite blur with GLSL in test example. Now I want to make LabelBMFont blur with it, how can I do?
`#ifdef GL_ES
precision mediump float;
#endif

varying vec4 v_fragmentColor;
varying vec2 v_texCoord;

uniform sampler2D CC_Texture0;

uniform vec2 blurSize;
uniform vec4 substract;

const float RADIUS = 0.75;

const float SOFTNESS = 0.6;

void main() {
vec4 sum = vec4(0.0);
sum += texture2D(CC_Texture0, v_texCoord - 4.0 * blurSize) * 0.05;
sum += texture2D(CC_Texture0, v_texCoord - 3.0 * blurSize) * 0.09;
sum += texture2D(CC_Texture0, v_texCoord - 2.0 * blurSize) * 0.12;
sum += texture2D(CC_Texture0, v_texCoord - 1.0 * blurSize) * 0.15;
sum += texture2D(CC_Texture0, v_texCoord ) * 0.16;
sum += texture2D(CC_Texture0, v_texCoord + 1.0 * blurSize) * 0.15;
sum += texture2D(CC_Texture0, v_texCoord + 2.0 * blurSize) * 0.12;
sum += texture2D(CC_Texture0, v_texCoord + 3.0 * blurSize) * 0.09;
sum += texture2D(CC_Texture0, v_texCoord + 4.0 * blurSize) * 0.05;

gl_FragColor = (sum - substract) * v_fragmentColor;

}`