//  Generated on <$_SCRIBE_DATE$>
//
//  Created by Olivier Prat on 04/12/17.
//  Copyright 2017 High Fidelity, Inc.
//
//  Distributed under the Apache License, Version 2.0.
//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
<@if not FADE_SLH@>
<@def FADE_SLH@>

<@func declareFadeFragmentCommon()@>


#define CATEGORY_COUNT    5

<@include Fade_shared.slh@>

layout(std140) uniform fadeParametersBuffer {
    FadeParameters fadeParameters[CATEGORY_COUNT];
};
uniform sampler2D fadeMaskMap;

struct FadeObjectParams {
    int category;
    float threshold;
    vec3 noiseOffset;
    vec3 baseOffset;
    vec3 baseInvSize;
};

vec2 hash2D(vec3 position) {
    return position.xy* vec2(0.1677,  0.221765) + position.z*0.561;
}

float noise3D(vec3 position) {
    float n = textureLod(fadeMaskMap, hash2D(position), 0.0).r;
    return pow(n, 1.0/2.2); // Remove sRGB. Need to fix this later directly in the texture
}

float evalFadeNoiseGradient(FadeObjectParams params, vec3 position) {
    // Do tri-linear interpolation
    vec3    noisePosition = position * fadeParameters[params.category]._noiseInvSizeAndLevel.xyz + params.noiseOffset;
    vec3    noisePositionFloored = floor(noisePosition);
    vec3    noisePositionFraction = fract(noisePosition);

    noisePositionFraction = noisePositionFraction*noisePositionFraction*(3.0 - 2.0*noisePositionFraction);

    float   noiseLowXLowYLowZ = noise3D(noisePositionFloored);
    float   noiseLowXHighYLowZ = noise3D(noisePositionFloored+vec3(0,1,0));
    float   noiseHighXLowYLowZ = noise3D(noisePositionFloored+vec3(1,0,0));
    float   noiseHighXHighYLowZ = noise3D(noisePositionFloored+vec3(1,1,0));
    float   noiseLowXLowYHighZ = noise3D(noisePositionFloored+vec3(0,0,1));
    float   noiseLowXHighYHighZ = noise3D(noisePositionFloored+vec3(0,1,1));
    float   noiseHighXLowYHighZ = noise3D(noisePositionFloored+vec3(1,0,1));
    float   noiseHighXHighYHighZ = noise3D(noisePositionFloored+vec3(1,1,1));
    vec4    maskLowZ = vec4(noiseLowXLowYLowZ, noiseLowXHighYLowZ, noiseHighXLowYLowZ, noiseHighXHighYLowZ);
    vec4    maskHighZ = vec4(noiseLowXLowYHighZ, noiseLowXHighYHighZ, noiseHighXLowYHighZ, noiseHighXHighYHighZ);
    vec4    maskXY = mix(maskLowZ, maskHighZ, noisePositionFraction.z);
    vec2    maskY = mix(maskXY.xy, maskXY.zw, noisePositionFraction.x);

    float noise = mix(maskY.x, maskY.y, noisePositionFraction.y);
    noise -= 0.5;   // Center on value 0
    return noise * fadeParameters[params.category]._noiseInvSizeAndLevel.w;
}

float evalFadeBaseGradient(FadeObjectParams params, vec3 position) {
    float gradient = length((position - params.baseOffset) * params.baseInvSize.xyz);
    gradient = gradient-0.5;  // Center on value 0.5
    gradient *= fadeParameters[params.category]._baseLevel;
    return gradient;
}

float evalFadeGradient(FadeObjectParams params, vec3 position) {
    float baseGradient = evalFadeBaseGradient(params, position);
    float noiseGradient = evalFadeNoiseGradient(params, position);
    float gradient = noiseGradient+baseGradient+0.5;

    return gradient;
}

float evalFadeAlpha(FadeObjectParams params, vec3 position) {
    return evalFadeGradient(params, position)-params.threshold;
}

void applyFadeClip(FadeObjectParams params, vec3 position) {
    if (evalFadeAlpha(params, position) < 0.0) {
        discard;
    }
}

void applyFade(FadeObjectParams params, vec3 position, out vec3 emissive) {
    float alpha = evalFadeAlpha(params, position);
    if (fadeParameters[params.category]._isInverted!=0) {
        alpha = -alpha;
    }

    if (alpha < 0.0) {
        discard;
    }
    
    float edgeMask = alpha * fadeParameters[params.category]._edgeWidthInvWidth.y;
    float edgeAlpha = 1.0-clamp(edgeMask, 0.0, 1.0);

    edgeMask = step(edgeMask, 1.0);
    edgeAlpha *= edgeAlpha; // Square to have a nice ease out
    vec4 color = mix(fadeParameters[params.category]._innerEdgeColor, fadeParameters[params.category]._outerEdgeColor, edgeAlpha);
    emissive = color.rgb * edgeMask * color.a;
}

<@endfunc@>

<@func declareFadeFragmentUniform()@>

uniform int fadeCategory;
uniform vec3 fadeNoiseOffset;
uniform vec3 fadeBaseOffset;
uniform vec3 fadeBaseInvSize;
uniform float fadeThreshold;

<@endfunc@>

<@func fetchFadeObjectParams(fadeParams)@>
    <$fadeParams$>.category = fadeCategory;
    <$fadeParams$>.threshold = fadeThreshold;
    <$fadeParams$>.noiseOffset = fadeNoiseOffset;
    <$fadeParams$>.baseOffset = fadeBaseOffset;
    <$fadeParams$>.baseInvSize = fadeBaseInvSize;
<@endfunc@>

<@func declareFadeFragmentVertexInput()@>

in vec4 _fadeData1;
in vec4 _fadeData2;
in vec4 _fadeData3;

<@endfunc@>

<@func fetchFadeObjectParamsInstanced(fadeParams)@>
    <$fadeParams$>.category = int(_fadeData1.w);
    <$fadeParams$>.threshold = _fadeData2.w;
    <$fadeParams$>.noiseOffset = _fadeData1.xyz;
    <$fadeParams$>.baseOffset = _fadeData2.xyz;
    <$fadeParams$>.baseInvSize = _fadeData3.xyz;
<@endfunc@>

<@func declareFadeFragment()@>
<$declareFadeFragmentCommon()$>
<$declareFadeFragmentUniform()$>
<@endfunc@>

<@func declareFadeFragmentInstanced()@>
<$declareFadeFragmentCommon()$>
<$declareFadeFragmentVertexInput()$>
<@endfunc@>

<@func declareFadeVertexInstanced()@>
out vec4 _fadeData1;
out vec4 _fadeData2;
out vec4 _fadeData3;
<@endfunc@>

<@func passThroughFadeObjectParams()@>
    _fadeData1 = inTexCoord2;
    _fadeData2 = inTexCoord3;
    _fadeData3 = inTexCoord4;    
<@endfunc@>

<@endif@>