/** 
 * @file class3\deferred\multiSpotLightF.glsl
 *
 * $LicenseInfo:firstyear=2022&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2022, Linden Research, Inc.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */
 
#extension GL_ARB_texture_rectangle : enable
#extension GL_ARB_shader_texture_lod : enable

/*[EXTRA_CODE_HERE]*/

#define DEBUG_PBR_LIGHT_TYPE         0 // Ouput gray if PBR multiSpot lights object
#define DEBUG_PBR_SPOT_ZERO          0 // Output zero for spotlight
#define DEBUG_PBR_SPOT               0
#define DEBUG_PBR_SPOT_DIFFUSE       0 // PBR diffuse lit
#define DEBUG_PBR_SPOT_SPECULAR      0 // PBR spec lit

#define DEBUG_LIGHT_FRUSTUM            0 // If projected light effects a surface
#define DEBUG_AMBIANCE_COLOR           0 // calculated ambiance color
#define DEBUG_AMBIANCE_AOE             0 // area of effect using inverse ambiance color
#define DEBUG_AMBIANCE_FINAL           0 // light color * ambiance color
#define DEBUG_NOISE                    0 // monochrome noise
#define DEBUG_SHADOW                   0 // Show inverted shadow
#define DEBUG_SPOT_DIFFUSE             0 // dot(n,l) * dist_atten
#define DEBUG_SPOT_NL                  0 // monochome area effected by light
#define DEBUG_SPOT_SPEC_POS            0
#define DEBUG_SPOT_REFLECTION          0 // color: pos reflected along n

#define DEBUG_PBR_LIGHT_H              0 // Half vector
#define DEBUG_PBR_LIHGT_L              0 // Light vector
#define DEBUG_PBR_LIGHT_NH             0 // colorized dot(n,h)
#define DEBUG_PBR_LIGHT_NL             0 // colorized dot(n,l)
#define DEBUG_PBR_LIGHT_NV             0 // colorized dot(n,v)
#define DEBUG_PBR_LIGHT_VH             0 // colorized dot(v,h)
#define DEBUG_PBR_LIGHT_DIFFUSE_COLOR  0 // non PBR spotlight
#define DEBUG_PBR_LIGHT_SPECULAR_COLOR 0 // non PBR spotlight
#define DEBUG_PBR_LIGHT_INTENSITY      0 // Light intensity
#define DEBUG_PBR_LIGHT_INTENSITY_NL   0 // Light intensity * dot(n,l)
#define DEBUG_PBR_LIGHT_BRDF_DIFFUSE   0 // like "fullbright" if no "nl" factor
#define DEBUG_PBR_LIGHT_BRDF_SPECULAR  0
#define DEBUG_PBR_LIGHT_BRDF_FINAL     0 // BRDF Diffuse + BRDF Specular


#ifdef DEFINE_GL_FRAGCOLOR
out vec4 frag_color;
#else
#define frag_color gl_FragColor
#endif

uniform sampler2DRect diffuseRect;
uniform sampler2DRect specularRect;
uniform sampler2DRect depthMap;
uniform sampler2DRect normalMap;
uniform sampler2DRect emissiveRect; // PBR linear packed Occlusion, Roughness, Metal. See: pbropaqueF.glsl
uniform samplerCube environmentMap;
uniform sampler2DRect lightMap;
uniform sampler2D noiseMap;
uniform sampler2D projectionMap; // rgba
uniform sampler2D lightFunc;

uniform mat4 proj_mat; //screen space to light space
uniform float proj_near; //near clip for projection
uniform vec3 proj_p; //plane projection is emitting from (in screen space)
uniform vec3 proj_n;
uniform float proj_focus; //distance from plane to begin blurring
uniform float proj_lod;  //(number of mips in proj map)
uniform float proj_range; //range between near clip and far clip plane of projection
uniform float proj_ambient_lod;
uniform float proj_ambiance;
uniform float near_clip;
uniform float far_clip;

uniform vec3 proj_origin; //origin of projection to be used for angular attenuation
uniform float sun_wash;
uniform int proj_shadow_idx;
uniform float shadow_fade;

// Light params
uniform vec3 center;
uniform float size;
uniform vec3 color;
uniform float falloff;

VARYING vec4 vary_fragcoord;
uniform vec2 screen_res;

uniform mat4 inv_proj;

vec3 BRDFLambertian( vec3 reflect0, vec3 reflect90, vec3 c_diff, float specWeight, float vh );
vec3 BRDFSpecularGGX( vec3 reflect0, vec3 reflect90, float alphaRoughness, float specWeight, float vh, float nl, float nv, float nh );
void calcHalfVectors(vec3 lv, vec3 n, vec3 v, out vec3 h, out vec3 l, out float nh, out float nl, out float nv, out float vh, out float lightDist);
bool clipProjectedLightVars(vec3 center, vec3 pos, out float dist, out float l_dist, out vec3 lv, out vec4 proj_tc );
vec3 getLightIntensitySpot(vec3 lightColor, float lightRange, float lightDistance, vec3 v);
vec4 getNormalEnvIntensityFlags(vec2 screenpos, out vec3 n, out float envIntensity);
vec3 getProjectedLightAmbiance(float amb_da, float attenuation, float lit, float nl, float noise, vec2 projected_uv);
vec3 getProjectedLightDiffuseColor(float light_distance, vec2 projected_uv );
vec3 getProjectedLightSpecularColor(vec3 pos, vec3 n);
vec2 getScreenXY(vec4 clip);
void initMaterial( vec3 diffuse, vec3 packedORM, out float alphaRough, out vec3 c_diff, out vec3 reflect0, out vec3 reflect90, out float specWeight );
vec3 srgb_to_linear(vec3 cs);
vec4 texture2DLodSpecular(vec2 tc, float lod);

vec3 colorized_dot(float x)
{
    if (x > 0.0) return vec3( 0, x, 0 );
    if (x < 0.0) return vec3( x, 0, 0 );
                 return vec3( 0, 0, 1 );
}

vec4 getPosition(vec2 pos_screen);

void main()
{
#if defined(LOCAL_LIGHT_KILL)
    discard;
#else
    vec3 final_color = vec3(0,0,0);
    vec2 tc          = getScreenXY(vary_fragcoord);
    vec3 pos         = getPosition(tc).xyz;

    vec3 lv;
    vec4 proj_tc;
    float dist, l_dist;
    if (clipProjectedLightVars(center, pos, dist, l_dist, lv, proj_tc))
    {
        discard;
    }

    float shadow = 1.0;
    
    if (proj_shadow_idx >= 0)
    {
        vec4 shd = texture2DRect(lightMap, tc);
        shadow = (proj_shadow_idx==0)?shd.b:shd.a;
        shadow += shadow_fade;
        shadow = clamp(shadow, 0.0, 1.0);        
    }

    float envIntensity;
    vec3 n;
    vec4 norm = getNormalEnvIntensityFlags(tc, n, envIntensity);

    float dist_atten = 1.0 - (dist + falloff)/(1.0 + falloff);

    lv = proj_origin-pos.xyz;
    vec3  h, l, v = -normalize(pos);
    float nh, nl, nv, vh, lightDist;
    calcHalfVectors(lv, n, v, h, l, nh, nl, nv, vh, lightDist);

    vec3 diffuse = texture2DRect(diffuseRect, tc).rgb;
    vec4 spec    = texture2DRect(specularRect, tc);
    vec3 dlit    = vec3(0, 0, 0);
    vec3 slit    = vec3(0, 0, 0);

    vec3 amb_rgb = vec3(0);

    if (GET_GBUFFER_FLAG(GBUFFER_FLAG_HAS_PBR))
    {
        vec3 colorDiffuse  = vec3(0);
        vec3 colorSpec     = vec3(0);
        vec3 colorEmissive = spec.rgb; // PBR sRGB Emissive.  See: pbropaqueF.glsl
        vec3 packedORM     = texture2DRect(emissiveRect, tc).rgb; // PBR linear packed Occlusion, Roughness, Metal. See: pbropaqueF.glsl
        float metal        = packedORM.b;

        // We need this additional test inside a light's frustum since a spotlight's ambiance can be applied
        if (proj_tc.x > 0.0 && proj_tc.x < 1.0
        &&  proj_tc.y > 0.0 && proj_tc.y < 1.0)
        {
            float lit = 0.0;
            float amb_da = 0.0;

            if (nl > 0.0)
            {
                amb_da += (nl*0.5 + 0.5) * proj_ambiance;
                lit = nl * dist_atten;

                vec3 c_diff, reflect0, reflect90;
                float alphaRough, specWeight;
                initMaterial( diffuse, packedORM, alphaRough, c_diff, reflect0, reflect90, specWeight );

                dlit = getProjectedLightDiffuseColor( l_dist, proj_tc.xy );
                slit = getProjectedLightSpecularColor( pos, n );

                colorDiffuse = shadow * lit * (dlit*0.5 + BRDFLambertian ( reflect0, reflect90, c_diff    , specWeight, vh ));
                colorSpec    = shadow * lit * (slit     + BRDFSpecularGGX( reflect0, reflect90, alphaRough, specWeight, vh, nl, nv, nh ));

      #if DEBUG_PBR_SPOT_DIFFUSE
                colorDiffuse = dlit.rgb; colorSpec = vec3(0);
      #endif
      #if DEBUG_PBR_SPOT_SPECULAR
                colorDiffuse = vec3(0); colorSpec = slit.rgb;
      #endif
      #if DEBUG_PBR_SPOT
                colorDiffuse = dlit; colorSpec = vec3(0);
                colorDiffuse *= nl;
                colorDiffuse *= shadow;
      #endif
            }

            amb_rgb = getProjectedLightAmbiance( amb_da, dist_atten, lit, nl, 1.0, proj_tc.xy );
            colorDiffuse += diffuse.rgb * amb_rgb;

  #if DEBUG_AMBIANCE_FINAL
            colorDiffuse = diffuse.rgb * amb_rgb; colorSpec = vec3(0);
  #endif
  #if DEBUG_LIGHT_FRUSTUM
            colorDiffuse = vec3(0,1,0); colorSpec = vec3(0);
  #endif
  #if DEBUG_NOISE
            float noise = texture2D(noiseMap, tc/128.0).b;
            colorDiffuse = vec3(noise); colorSpec = vec3(0);
  #endif
        }

  #if DEBUG_PBR_LIGHT_TYPE
        colorDiffuse = vec3(0.5); colorSpec = vec3(0);
  #endif

  #if DEBUG_PBR_LIGHT_H
        colorDiffuse = h*0.5 + 0.5;  colorSpec = vec3(0);
  #endif
  #if DEBUG_PBR_LIHGT_L
        colorDiffuse = l*0.5 + 0.5;  colorSpec = vec3(0);
  #endif
  #if DEBUG_PBR_LIGHT_NH
        colorDiffuse = colorized_dot(nh); colorSpec = vec3(0);
  #endif
  #if DEBUG_PBR_LIGHT_NL
        colorDiffuse = colorized_dot(nl); colorSpec = vec3(0);
  #endif
  #if DEBUG_PBR_LIGHT_NV
        colorDiffuse = colorized_dot(nv); colorSpec = vec3(0);
  #endif
  #if DEBUG_PBR_LIGHT_VH
        colorDiffuse = colorized_dot(vh); colorSpec = vec3(0);
  #endif
  #if DEBUG_PBR_LIGHT_DIFFUSE_COLOR
        colorDiffuse = dlit;
  #endif
  #if DEBUG_PBR_LIGHT_SPECULAR_COLOR
        colorDiffuse = slit;
  #endif
  #if DEBUG_PBR_LIGHT_INTENSITY
        colorDiffuse = getLightIntensitySpot( color, size, lightDist, v ); colorSpec = vec3(0);
//        colorDiffuse = nl * dist_atten;
  #endif
  #if DEBUG_PBR_LIGHT_INTENSITY_NL
        colorDiffuse = getLightIntensitySpot( color, size, lightDist, v ) * nl; colorSpec = vec3(0);
  #endif
  #if DEBUG_PBR_LIGHT_BRDF_DIFFUSE
        vec3 c_diff, reflect0, reflect90;
        float alphaRough, specWeight;
        initMaterial( diffuse, packedORM, alphaRough, c_diff, reflect0, reflect90, specWeight );

        colorDiffuse = BRDFLambertian ( reflect0, reflect90, c_diff    , specWeight, vh );
        colorSpec = vec3(0);
  #endif
  #if DEBUG_PBR_LIGHT_BRDF_SPECULAR
        vec3 c_diff, reflect0, reflect90;
        float alphaRough, specWeight;
        initMaterial( diffuse, packedORM, alphaRough, c_diff, reflect0, reflect90, specWeight );

        colorDiffuse = vec3(0);
        colorSpec = BRDFSpecularGGX( reflect0, reflect90, alphaRough, specWeight, vh, nl, nv, nh );
  #endif
  #if DEBUG_PBR_LIGHT_BRDF_FINAL
        vec3 c_diff, reflect0, reflect90;
        float alphaRough, specWeight;
        initMaterial( diffuse, packedORM, alphaRough, c_diff, reflect0, reflect90, specWeight );
        colorDiffuse = nl * BRDFLambertian ( reflect0, reflect90, c_diff    , specWeight, vh );
        colorSpec    = nl * BRDFSpecularGGX( reflect0, reflect90, alphaRough, specWeight, vh, nl, nv, nh );
  #endif

        final_color = colorDiffuse + colorSpec;
    }
    else
    {
        dist_atten *= dist_atten;
        dist_atten *= 2.0;
        if (dist_atten <= 0.0)
        {
            discard;
        }

        float noise = texture2D(noiseMap, tc/128.0).b;
        if (proj_tc.z > 0.0 &&
            proj_tc.x < 1.0 &&
            proj_tc.y < 1.0 &&
            proj_tc.x > 0.0 &&
            proj_tc.y > 0.0)
        {
            float amb_da = 0;
            float lit = 0.0;

            if (nl > 0.0)
            {
                lit = nl * dist_atten * noise;

                dlit = getProjectedLightDiffuseColor( l_dist, proj_tc.xy );

                final_color = dlit*lit*diffuse*shadow;

                // unshadowed for consistency between forward and deferred?
                amb_da += (nl*0.5+0.5) /* * (1.0-shadow) */ * proj_ambiance;
            }
        
            amb_rgb = getProjectedLightAmbiance( amb_da, dist_atten, lit, nl, noise, proj_tc.xy );
            final_color += diffuse.rgb * amb_rgb;
        }
    
        if (spec.a > 0.0)
        {
            dlit *= min(nl*6.0, 1.0) * dist_atten;

            float fres = pow(1 - vh, 5)*0.4+0.5;

            float gtdenom = 2 * nh;
            float gt = max(0, min(gtdenom * nv / vh, gtdenom * nl / vh));
                                
            if (nh > 0.0)
            {
                float scol = fres*texture2D(lightFunc, vec2(nh, spec.a)).r*gt/(nh*nl);
                vec3 speccol = dlit*scol*spec.rgb*shadow;
                speccol = clamp(speccol, vec3(0), vec3(1));
                final_color += speccol;
            }
        }   

        if (envIntensity > 0.0)
        {
            vec3 ref = reflect(normalize(pos), n);
        
            //project from point pos in direction ref to plane proj_p, proj_n
            vec3 pdelta = proj_p-pos;
            float ds = dot(ref, proj_n);
        
            if (ds < 0.0)
            {
                vec3 pfinal = pos + ref * dot(pdelta, proj_n)/ds;
            
                vec4 stc = (proj_mat * vec4(pfinal.xyz, 1.0));

                if (stc.z > 0.0)
                {
                    stc /= stc.w;
                                
                    if (stc.x < 1.0 &&
                        stc.y < 1.0 &&
                        stc.x > 0.0 &&
                        stc.y > 0.0)
                    {
                        final_color += color.rgb * texture2DLodSpecular(stc.xy, (1 - spec.a) * (proj_lod * 0.6)).rgb * shadow * envIntensity;
                    }
                }
            }
  #if DEBUG_SPOT_REFLECTION
            final_color = ref;
  #endif
        }

#if DEBUG_LIGHT_FRUSTUM
        if (proj_tc.x > 0.0 && proj_tc.x < 1.0
        &&  proj_tc.y > 0.0 && proj_tc.y < 1.0)
        {
            final_color = vec3(0,0,1);
        }
#endif
    }

#if DEBUG_AMBIANCE_AOE
    if (proj_tc.x > 0.0 && proj_tc.x < 1.0
    &&  proj_tc.y > 0.0 && proj_tc.y < 1.0)
    {
        final_color = 1.0 - amb_rgb;
    }
#endif
#if DEBUG_AMBIANCE_COLOR
    if (proj_tc.x > 0.0 && proj_tc.x < 1.0
    &&  proj_tc.y > 0.0 && proj_tc.y < 1.0)
    {
        final_color = amb_rgb;
    }
#endif
#if DEBUG_SHADOW
    final_color = 1.0 - vec3(shadow);
#endif
#if DEBUG_SPOT_DIFFUSE
    final_color = vec3(nl * dist_atten);
#endif
#if DEBUG_SPOT_NL
    final_color =vec3(nl);
#endif
#if DEBUG_SPOT_SPEC_POS
    vec3 ref = reflect(normalize(pos), n);
    vec3 pdelta = proj_p-pos;
    float ds = dot(ref, proj_n);
    final_color = pos + ref * dot(pdelta, proj_n)/ds;
#endif
#if DEBUG_SPOT_REFLECTION
    final_color = reflect(normalize(pos), n);
#endif
#if DEBUG_SPOT_ZERO
    final_color = vec3(0);
#endif

    //not sure why, but this line prevents MATBUG-194
    final_color = max(final_color, vec3(0.0));

    //output linear
    frag_color.rgb = final_color;
    frag_color.a = 0.0;
#endif // LOCAL_LIGHT_KILL
}