lambert.frag

	// fragment shader
 
precision lowp float;
 
//varying vec4 outputColor;
varying vec3 cnormal; 
 
void main()
{
    vec3 col = cnormal.xyz;//vec3(1,1,1) * dot(cnormal, vec3(0,1,0));
    gl_FragColor = vec4(col.x, col.y, col.z, 1);
}

lambert.vert

// vertex shader
 
precision lowp float;
 
uniform mat4 modelViewProjectionMatrix;
uniform mat4 normalMatrix;
attribute vec4 position;
attribute vec4 normal;

varying vec3 cnormal;
 
void main(){
    gl_Position = modelViewProjectionMatrix * position;
    cnormal = normal.xyz;//normalize( normalMatrix * normal ).xyz;
}

ofApp.mm

ofSpherePrimitive cp;
ofShader shader;

//--------------------------------------------------------------
void ofApp::setup(){
    
    cp.enableNormals();
    cp.enableColors();
    cp.set(10, 20);
    cp.setScale(10);
    cp.setPosition(0,0,-500);
    
    if(!shader.load("lambert"))
        return;

}

//--------------------------------------------------------------
void ofApp::update(){

}

//--------------------------------------------------------------
void ofApp::draw(){
    
    static float rot = 0.0f;
    ofSetColor(255);
    cp.setOrientation(ofVec3f(0,rot,rot));
    shader.begin();
    cp.draw();

    shader.end();
    
    rot += 1.0f;
}