Phong Shader: Fixed light specular component rotates with camera

Question

I wrote a Phong shader for WebGL. My Scene supports camera rotation using Euler Angles. The light should be fixed in the scene. As soon as I rotate the camera the specular effects on objects move as well. Translation also seems to have strange effects on the specular component. I (hopefully) made sure that calculations are performed in eye space. I first want to find out if my shaders are correct.

Here is my code:

Vertex Shader

struct Light {
  vec3 position;

  /* ... */
};

uniform Light u_light;
uniform mat4 u_modelViewProjMat;
uniform mat4 u_modelViewMat;
uniform mat4 u_viewMat;
uniform mat3 u_normalMat;

in vec3 a_position;
in vec3 a_normal;
in vec2 a_texCoord;

out vec2 v_texCoord;
out vec3 v_normal;
out vec3 f_position;
out vec3 v_lightPos;

void main() {
  v_normal = u_normalMat * a_normal;
  v_texCoord = a_texCoord;
  f_position = vec3(u_modelViewMat * vec4(a_position, 1.0));
  v_lightPos = vec3(u_viewMat * vec4(u_light.position, 1.0));
  gl_Position = u_modelViewProjMat * vec4(a_position, 1.0);
}

Fragment Shader

struct Material {
  sampler2D diffuse;
  vec3 specular;
  float shininess;
};

struct Light {
    /* ... */
    vec3 ambient;
    vec3 diffuse;
    vec3 specular;
};

uniform Material u_material;
uniform Light u_light;
uniform vec3 u_eyePosition;

in vec2 v_texCoord;
in vec3 v_normal;
in vec3 f_position;
in vec3 v_lightPos;

out vec4 outColor;

void main() {
  vec3 texture = vec3(texture(u_material.diffuse, v_texCoord));

  // ambient
  vec3 ambient = u_light.ambient * texture;

  // diffuse
  vec3 normal = normalize(v_normal);
  vec3 lightDir = normalize(v_lightPos - f_position);
  float diff = max(dot(normal, lightDir), 0.0);
  vec3 diffuse = u_light.diffuse * diff * texture;

  // specular
  vec3 viewDir = normalize(u_eyePosition - f_position);
  vec3 reflectDir = reflect(-lightDir, normal);
  float spec = pow(max(dot(viewDir, reflectDir), 0.0), u_material.shininess);
  vec3 specular = u_light.specular * (spec * u_material.specular);

  outColor = vec4((ambient + diffuse + specular), 1.0);
}

Answer 1

f_position is a camera space position, so to get the viewDir vector for your specular component you should only perform vec3 viewDir = normalize(-f_position); or work with world space coordinates