#version 300 es
precision mediump float;
uniform sampler2D s_texture;
uniform int u_texture_env_mode;
uniform vec4 u_light_ambient;
uniform vec4 u_light_diffuse;
uniform vec4 u_light_specular;
uniform vec3 u_light_dir;
uniform float u_material_shiness;
in vec3 v_position;
in vec2 v_texcoord;
in vec3 v_normal;
out vec4 o_fragColor;
void main()
{
    const int texture_env_mode_replace = 0x1E01;
    const int texture_env_mode_modulate = 0x2100;
    vec4 color = texture( s_texture, v_texcoord );
    if (u_texture_env_mode==texture_env_mode_replace)
       o_fragColor = color;
    else if (u_texture_env_mode==texture_env_mode_modulate){
       // ambient
       vec4 ambient = u_light_ambient;
       // diffuse
       vec3 norm = normalize(v_normal.xyz);
       vec3 lightDir = normalize(u_light_dir);
       float diff = max(dot(norm, lightDir), 0.0);
       vec4 diffuse = u_light_diffuse * diff;
       // specular
       vec4 specular = vec4(0, 0, 0, 1);
       if (u_material_shiness>0.0){
		       vec3 viewDir = normalize(-v_position);
		       vec3 reflectDir = normalize(reflect(-lightDir, norm));
		       float spec = pow(max(dot(viewDir, reflectDir), 0.0), u_material_shiness);
		       specular = u_light_specular * spec;
       }
       o_fragColor = (ambient + diffuse)*color  + specular;
    }
    else
      o_fragColor = vec4(0, 0, 0, 1);
}