Cocos2dx-JS 在 Sprite 上使用 Shader

//例如如下一个简单的变色程序，蓝色变红色 ,js 代码:

        var url = "res/sb.jpg";
        var sp = new cc.Sprite(url);
        sp.setAnchorPoint(0,0);
        this.addChild(sp);
        this.shader = new cc.GLProgram("res/Shaders/example_Flower.vsh", "res/Shaders/example_Flower.fsh");
        this.shader.retain();
        this.shader.link();
        this.shader.updateUniforms();
        var program = this.shader.getProgram();
        sp.shaderProgram = this.shader;

VertexShader

attribute vec4 a_position;
attribute vec2 a_texCoord;
attribute vec4 a_color;

#ifdef GL_ES
	varying lowp vec4 v_fragmentColor;
	varying mediump vec2 v_texCoord;
#else
	varying vec4 v_fragmentColor;
	varying vec2 v_texCoord;
#endif

void main()
{
    gl_Position = CC_PMatrix * a_position;
    v_fragmentColor = a_color;
    v_texCoord = a_texCoord;
}

FragmentShader

#ifdef GL_ES
    precision lowp float;
#endif

varying vec4 v_fragmentColor;
varying vec2 v_texCoord;

void main()
{
    gl_FragColor = v_fragmentColor * texture2D(CC_Texture0, v_texCoord);
    float r = gl_FragColor[0];
    float g = gl_FragColor[1];
    float b = gl_FragColor[2];
    float a = gl_FragColor[3];
    if(b > r && b > g && b > (r*0.5 + g*0.5)*1.5) {
        gl_FragColor[0] = b;
        gl_FragColor[2] = r;
    }
}