#version 100
precision mediump float;

varying vec2 texcoord;
varying vec3 v_normal;
varying float v_position;
varying vec3 v_cam_normal;
uniform sampler2D u_image0;
uniform vec2 fog;

void main() {

  vec3  N      = normalize(v_cam_normal);
    vec3  L      = vec3(0.0, 0.0, 1.0);
    float NdotL  = dot(N, L)/ 3.0 + 1.0 + (1.0/3.0);

  float fogAmount = smoothstep(fog.x, fog.y, v_position); 

  float light = -dot(vec3(0.1, -1.0, 0.3), v_normal) / 3.0 + 1.0;

  gl_FragColor = 
    texture2D(u_image0, texcoord) 
    * vec4(1.0 - fogAmount, 1.0 - fogAmount, 1.0 - fogAmount, 1.0 - fogAmount)
    * vec4(light, light, light, 1.0)
    * vec4(NdotL, NdotL, NdotL, 1.0);
  if(gl_FragColor.a < 0.0000001)
    discard;
}