<script id= "vertexShader" type= "x-shader/x-vertex">

            attribute vec4 vertexPosition;
            attribute vec3 vertexNormal;
            uniform mat4 projectionMatrix;
            uniform mat4 modelMatrix;
            uniform vec3 lightDirection;
            uniform vec3 lightColor;
            uniform vec3 objectColor;
            varying mediump vec3 fragmentColor;

            void main() {
            vec4 p = modelMatrix * vertexPosition;
            vec3 n = normalize(mat3(modelMatrix) * vertexNormal);
            vec3 l = normalize(mat3(modelMatrix) * lightDirection);
            vec3 v = normalize(vec3(-p));
            vec3 h = normalize(v + l);
            float d = max(dot(n, l) , 0.0);
            float s = pow(max(dot(n, h), 0.0), 100.0);

            fragmentColor = lightColor * (objectColor * d + s);
            gl_Position = projectionMatrix * modelMatrix * vertexPosition;

        }