Basic glsl lightning

lightning.glsl

// Vertex

varying vec3 vNormal;

void main() {
    vNormal = normal;
    gl_Position = projectionMatrix * viewMatrix * modelMatrix * vec4(position, 1.0);
}

// Fragment

uniform vec3 lightPosition;
uniform vec3 lightColor;
uniform vec3 objectColor;
uniform vec3 ambient;
varying vec3 vNormal;

varying vec2 resolution;

void main() {
    // diffuse
    vec3 norm = normalize(vNormal);
    float brightness = max(0.0, dot(norm, lightPosition));
    vec3 diffuse = brightness * lightColor;

    gl_FragColor = vec4((ambient + diffuse) * objectColor, 1.0);
}