osg ifc数据渲染着色器

//顶点着色器
static const char* vertShader = {
    "varying vec4 color;
"
    "void main(void)
"
    "{
"
    "color = gl_Vertex;
"
    "gl_Position=gl_ModelViewProjectionMatrix*gl_Vertex;
"
    "}
"
};

//片元着色器
static const char* fragShader = {
    "varying vec4 color;
"
    "void main(void)
"
    "{
"
    "    gl_FragColor = clamp(color,0.1,0.8);
"
    "}
"
};