#version 100
precision mediump float;

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

void main() {

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

  float light = -dot(vec3(0.0, -1.0, 0.0), v_normal) / 3.0 + 1.0 + (1.0/3.0);

  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);
  if(gl_FragColor.a < 0.0000001)
    discard;
}