uniform vec3 uAmbientColor;
uniform vec3 uDiffuseColor;
uniform vec3 uSpecularColor;
uniform float uShininess;
uniform float uOpacity;
uniform bool enableDiffuse1;
uniform bool enableDiffuse2;
uniform bool enableSpecular;
uniform sampler2D tDiffuse1;
uniform sampler2D tDiffuse2;
uniform sampler2D tDetail;
uniform sampler2D tNormal;
uniform sampler2D tSpecular;
uniform sampler2D tDisplacement;
uniform float uNormalScale;
uniform vec2 uRepeatOverlay;
uniform vec2 uOffset;
varying vec3 vTangent;
varying vec3 vBinormal;
varying vec3 vNormal;
varying vec2 vUv;
uniform vec3 ambientLightColor;
uniform mat4 viewMatrix;

#define MAX_POINT_LIGHTS 1
//#define USE_FOG
//#define FOG_EXP2

#if MAX_POINT_LIGHTS > 0
uniform vec3 pointLightColor[ MAX_POINT_LIGHTS ];
uniform vec3 pointLightPosition[ MAX_POINT_LIGHTS ];
uniform float pointLightDistance[ MAX_POINT_LIGHTS ];
#endif

varying vec3 vViewPosition;

// CHUNK: fog_pars_fragment
#ifdef USE_FOG
uniform vec3 fogColor;
#ifdef FOG_EXP2
uniform float fogDensity;
#else
uniform float fogNear;
uniform float fogFar;
#endif
#endif

void main() {
    gl_FragColor = vec4( vec3( 1.0 ), uOpacity );
    vec3 specularTex = vec3( 1.0 );
    vec2 uvOverlay = uRepeatOverlay * vUv + uOffset;
    vec3 normalTex = texture2D( tDetail, uvOverlay ).xyz * 2.0 - 1.0;
    normalTex.xy *= uNormalScale;
    normalTex = normalize( normalTex );

    vec4 colDiffuse1 = texture2D( tDiffuse1, uvOverlay );
    vec4 colDiffuse2 = texture2D( tDiffuse2, uvOverlay );
    gl_FragColor = gl_FragColor * mix ( colDiffuse1, colDiffuse2, 1.0 - texture2D( tDisplacement, vUv) );

    specularTex = texture2D( tSpecular, uvOverlay ).xyz;

    mat3 tbn= mat3( vTangent, vBinormal, vNormal );
    vec3 finalNormal = tbn * normalTex;
    vec3 normal = normalize( finalNormal );
    vec3 viewPosition = normalize( vViewPosition );

    // point lights
#if MAX_POINT_LIGHTS > 0
    vec3 pointDiffuse = vec3( 0.0 );
    vec3 pointSpecular = vec3( 0.0 );
    for ( int i = 0; i < MAX_POINT_LIGHTS; i ++ ) {
        vec4 lPosition = viewMatrix * vec4( pointLightPosition[ i ], 1.0 );
        vec3 lVector = lPosition.xyz + vViewPosition.xyz;
        float lDistance = 1.0;
        if ( pointLightDistance[ i ] > 0.0 )
            lDistance = 1.0 - min( ( length( lVector ) / pointLightDistance[ i ] ), 1.0 );
        lVector = normalize( lVector );
        vec3 pointHalfVector = normalize( lVector + viewPosition );
        float pointDistance = lDistance;
        float pointDotNormalHalf = max( dot( normal, pointHalfVector ), 0.0 );
        float pointDiffuseWeight = max( dot( normal, lVector ), 0.0 );
        float pointSpecularWeight = specularTex.r * pow( pointDotNormalHalf, uShininess );
        pointDiffuse += pointDistance * pointLightColor[ i ] * uDiffuseColor * pointDiffuseWeight;
        pointSpecular += pointDistance * pointLightColor[ i ] * uSpecularColor * pointSpecularWeight * pointDiffuseWeight;
    }
#endif

    // all lights contribution summation
    vec3 totalDiffuse = vec3( 0.0 );
    vec3 totalSpecular = vec3( 0.0 );


#if MAX_POINT_LIGHTS > 0
    totalDiffuse += pointDiffuse;
    totalSpecular += pointSpecular;
#endif

    gl_FragColor.xyz = gl_FragColor.xyz * ( totalDiffuse + ambientLightColor * uAmbientColor + totalSpecular );

    //CHUNK: fog_fragment
#ifdef USE_FOG
    float depth = gl_FragCoord.z / gl_FragCoord.w;
#ifdef FOG_EXP2
    const float LOG2 = 1.442695;
    float fogFactor = exp2( - fogDensity * fogDensity * depth * depth * LOG2 );
    fogFactor = 1.0 - clamp( fogFactor, 0.0, 1.0 );
#else
    float fogFactor = smoothstep( fogNear, fogFar, depth );
#endif
    gl_FragColor = mix( gl_FragColor, vec4( fogColor, gl_FragColor.w ), fogFactor );
#endif
}