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HDR: Water rendering

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This commit is contained in:
Fernando García Liñán 2021-08-25 04:17:09 +02:00
parent eea955168e
commit 9983a0c68c
7 changed files with 611 additions and 54 deletions
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38
Compositor/HDR/hdr.xml
View file

@ -761,6 +761,44 @@
</attachment>
</pass>
<pass>
<name>water</name>
<type>quad</type>
<effect>Effects/HDR/water-lighting</effect>
<binding>
<unit>0</unit>
<buffer>gbuffer0</buffer>
</binding>
<binding>
<unit>1</unit>
<buffer>gbuffer1</buffer>
</binding>
<binding>
<unit>3</unit>
<buffer>depth-stencil</buffer>
</binding>
<binding>
<unit>9</unit>
<buffer>prefiltered-envmap</buffer>
</binding>
<binding>
<unit>11</unit>
<buffer>aerial-perspective</buffer>
</binding>
<binding>
<unit>12</unit>
<buffer>transmittance</buffer>
</binding>
<attachment>
<component>color0</component>
<buffer>hdr-result</buffer>
</attachment>
<attachment>
<component>stencil</component>
<buffer>depth-stencil</buffer>
</attachment>
</pass>
<!--
Main forward pass
Render all objects that couldn't be rendered on the G-Buffer, mainly

49
Effects/HDR/water-lighting.eff Normal file
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@ -0,0 +1,49 @@
<?xml version="1.0" encoding="utf-8"?>
<PropertyList>
<name>Effects/HDR/water-lighting</name>
<technique n="1">
<pass>
<stencil>
<function>equal</function>
<value>3</value>
</stencil>
<program>
<vertex-shader>Shaders/HDR/trivial.vert</vertex-shader>
<fragment-shader>Shaders/HDR/water-lighting.frag</fragment-shader>
<fragment-shader>Shaders/HDR/gbuffer-include.frag</fragment-shader>
<fragment-shader>Shaders/HDR/aerial-perspective-include.frag</fragment-shader>
</program>
<uniform>
<name>gbuffer0_tex</name>
<type>sampler-2d</type>
<value type="int">0</value>
</uniform>
<uniform>
<name>gbuffer1_tex</name>
<type>sampler-2d</type>
<value type="int">1</value>
</uniform>
<uniform>
<name>depth_tex</name>
<type>sampler-2d</type>
<value type="int">3</value>
</uniform>
<uniform>
<name>prefiltered_envmap</name>
<type>sampler-cube</type>
<value type="int">9</value>
</uniform>
<!-- Aerial perspective include -->
<uniform>
<name>aerial_perspective_lut</name>
<type>sampler-2d</type>
<value type="int">11</value>
</uniform>
<uniform>
<name>transmittance_lut</name>
<type>sampler-2d</type>
<value type="int">12</value>
</uniform>
</pass>
</technique>
</PropertyList>

131
Effects/water.eff
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@ -207,12 +207,6 @@
<!-- END fog include -->
</parameters>
<generate>
<tangent type="int">6</tangent>
<binormal type="int">7</binormal>
</generate>
<technique n="1">
<predicate>
<and>
@ -1449,4 +1443,129 @@
<!-- END fog include -->
</pass>
</technique>
<technique n="108">
<scheme>hdr-geometry</scheme>
<pass>
<!-- Reverse floating point depth buffer -->
<depth>
<function>gequal</function>
<near>1.0</near>
<far>0.0</far>
</depth>
<stencil>
<function>always</function>
<value>3</value>
<pass>replace</pass>
</stencil>
<blend>0</blend>
<cull-face>back</cull-face>
<render-bin>
<bin-number><use>render-bin/bin-number</use></bin-number>
<bin-name><use>render-bin/bin-name</use></bin-name>
</render-bin>
<texture-unit>
<unit>0</unit>
<image><use>texture[2]/image</use></image>
<type><use>texture[2]/type</use></type>
<filter><use>texture[2]/filter</use></filter>
<wrap-s><use>texture[2]/wrap-s</use></wrap-s>
<wrap-t><use>texture[2]/wrap-t</use></wrap-t>
<internal-format><use>texture[2]/internal-format</use></internal-format>
</texture-unit>
<texture-unit>
<unit>1</unit>
<image><use>texture[3]/image</use></image>
<type><use>texture[3]/type</use></type>
<filter><use>texture[3]/filter</use></filter>
<wrap-s><use>texture[3]/wrap-s</use></wrap-s>
<wrap-t><use>texture[3]/wrap-t</use></wrap-t>
<internal-format><use>texture[3]/internal-format</use></internal-format>
</texture-unit>
<texture-unit>
<unit>2</unit>
<image><use>texture[6]/image</use></image>
<type><use>texture[6]/type</use></type>
<filter><use>texture[6]/filter</use></filter>
<wrap-s><use>texture[6]/wrap-s</use></wrap-s>
<wrap-t><use>texture[6]/wrap-t</use></wrap-t>
<internal-format><use>texture[6]/internal-format</use></internal-format>
</texture-unit>
<texture-unit>
<unit>3</unit>
<image><use>texture[8]/image</use></image>
<type><use>texture[8]/type</use></type>
<filter><use>texture[8]/filter</use></filter>
<wrap-s><use>texture[8]/wrap-s</use></wrap-s>
<wrap-t><use>texture[8]/wrap-t</use></wrap-t>
<internal-format><use>texture[8]/internal-format</use></internal-format>
</texture-unit>
<program>
<vertex-shader>Shaders/HDR/geometry-water.vert</vertex-shader>
<fragment-shader>Shaders/HDR/geometry-water.frag</fragment-shader>
<fragment-shader>Shaders/HDR/gbuffer-include.frag</fragment-shader>
</program>
<uniform>
<name>water_normalmap</name>
<type>sampler-2d</type>
<value type="int">0</value>
</uniform>
<uniform>
<name>water_dudvmap</name>
<type>sampler-2d</type>
<value type="int">1</value>
</uniform>
<uniform>
<name>perlin_normalmap</name>
<type>sampler-2d</type>
<value type="int">2</value>
</uniform>
<uniform>
<name>water_colormap</name>
<type>sampler-2d</type>
<value type="int">3</value>
</uniform>
<uniform>
<name>WindE</name>
<type>float</type>
<value><use>windE</use></value>
</uniform>
<uniform>
<name>WindN</name>
<type>float</type>
<value><use>windN</use></value>
</uniform>
<uniform>
<name>WaveFreq</name>
<type>float</type>
<value><use>WaveFreq</use></value>
</uniform>
<uniform>
<name>WaveAmp</name>
<type>float</type>
<value><use>WaveAmp</use></value>
</uniform>
<uniform>
<name>WaveSharp</name>
<type>float</type>
<value><use>WaveSharp</use></value>
</uniform>
<uniform>
<name>WaveAngle</name>
<type>float</type>
<value><use>WaveAngle</use></value>
</uniform>
<uniform>
<name>WaveFactor</name>
<type>float</type>
<value><use>WaveFactor</use></value>
</uniform>
<uniform>
<name>WaveDAngle</name>
<type>float</type>
<value><use>WaveDAngle</use></value>
</uniform>
</pass>
</technique>
</PropertyList>

49
Effects/ws30water.eff
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@ -1,7 +1,7 @@
<?xml version="1.0" encoding="utf-8"?>
<PropertyList>
<name>Effects/ws30water</name>
<inherits-from>Effects/water</inherits-from>
<inherits-from>Effects/water</inherits-from>
<technique n="1">
<pass n="0">
<!-- Hardcoded texture unit as we don't do a material lookup -->
@ -114,51 +114,4 @@
</texture-unit>
</pass>
</technique>
<technique n="109">
<scheme>hdr-geometry</scheme>
<pass>
<!-- Reverse floating point depth buffer -->
<depth>
<function>gequal</function>
<near>1.0</near>
<far>0.0</far>
</depth>
<stencil>
<function>always</function>
<value>3</value>
<pass>replace</pass>
</stencil>
<blend><use>transparent</use></blend>
<alpha-test><use>transparent</use></alpha-test>
<shade-model>smooth</shade-model>
<cull-face>back</cull-face>
<render-bin>
<bin-number><use>render-bin/bin-number</use></bin-number>
<bin-name><use>render-bin/bin-name</use></bin-name>
</render-bin>
<texture-unit>
<unit>0</unit>
<type>2d</type>
<image>Textures/Terrain/water.png</image>
<filter>linear-mipmap-linear</filter>
<wrap-s>repeat</wrap-s>
<wrap-t>repeat</wrap-t>
<environment>
<mode>modulate</mode>
</environment>
</texture-unit>
<program>
<vertex-shader>Shaders/HDR/geometry.vert</vertex-shader>
<fragment-shader>Shaders/HDR/geometry.frag</fragment-shader>
<fragment-shader>Shaders/HDR/gbuffer-include.frag</fragment-shader>
</program>
<uniform>
<name>color_tex</name>
<type>sampler-2d</type>
<value type="int">0</value>
</uniform>
</pass>
</technique>
</PropertyList>

214
Shaders/HDR/geometry-water.frag Normal file
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@ -0,0 +1,214 @@
#version 330 core
layout(location = 0) out vec4 gbuffer0;
layout(location = 1) out vec2 gbuffer1;
in vec4 waterTex1;
in vec4 waterTex2;
in mat3 TBN;
in vec3 ecPosition;
in vec2 TopoUV;
uniform sampler2D perlin_normalmap;
uniform sampler2D water_dudvmap;
uniform sampler2D water_normalmap;
uniform sampler2D water_colormap;
uniform float WindE;
uniform float WindN;
uniform float WaveFreq;
uniform float WaveAmp;
uniform float WaveSharp;
uniform float WaveAngle;
uniform float WaveFactor;
uniform float WaveDAngle;
uniform float osg_SimulationTime;
uniform vec3 fg_SunDirection;
vec2 encodeNormal(vec3 n);
vec3 decodeSRGB(vec3 screenRGB);
void rotationmatrix(float angle, out mat4 rotmat)
{
rotmat = mat4( cos( angle ), -sin( angle ), 0.0, 0.0,
sin( angle ), cos( angle ), 0.0, 0.0,
0.0 , 0.0 , 1.0, 0.0,
0.0 , 0.0 , 0.0, 1.0 );
}
// wave functions ///////////////////////
struct Wave {
float freq; // 2*PI / wavelength
float amp; // amplitude
float phase; // speed * 2*PI / wavelength
vec2 dir;
};
Wave wave0 = Wave(1.0, 1.0, 0.5, vec2(0.97, 0.25));
Wave wave1 = Wave(2.0, 0.5, 1.3, vec2(0.97, -0.25));
Wave wave2 = Wave(1.0, 1.0, 0.6, vec2(0.95, -0.3));
Wave wave3 = Wave(2.0, 0.5, 1.4, vec2(0.99, 0.1));
float evaluateWave(in Wave w, vec2 pos, float t)
{
return w.amp * sin( dot(w.dir, pos) * w.freq + t * w.phase);
}
// derivative of wave function
float evaluateWaveDeriv(Wave w, vec2 pos, float t)
{
return w.freq * w.amp * cos( dot(w.dir, pos)*w.freq + t*w.phase);
}
// sharp wave functions
float evaluateWaveSharp(Wave w, vec2 pos, float t, float k)
{
return w.amp * pow(sin( dot(w.dir, pos)*w.freq + t*w.phase)* 0.5 + 0.5 , k);
}
float evaluateWaveDerivSharp(Wave w, vec2 pos, float t, float k)
{
return k*w.freq*w.amp * pow(sin( dot(w.dir, pos)*w.freq + t*w.phase)* 0.5 + 0.5 , k - 1) * cos( dot(w.dir, pos)*w.freq + t*w.phase);
}
void sumWaves(float angle, float dangle, float windScale, float factor, out float ddx, float ddy)
{
mat4 RotationMatrix;
float deriv;
vec4 P = waterTex1 * 1024;
rotationmatrix(radians(angle + dangle * windScale + 0.6 * sin(P.x * factor)), RotationMatrix);
P *= RotationMatrix;
P.y += evaluateWave(wave0, P.xz, osg_SimulationTime);
deriv = evaluateWaveDeriv(wave0, P.xz, osg_SimulationTime );
ddx = deriv * wave0.dir.x;
ddy = deriv * wave0.dir.y;
P.y += evaluateWave(wave1, P.xz, osg_SimulationTime);
deriv = evaluateWaveDeriv(wave1, P.xz, osg_SimulationTime);
ddx += deriv * wave1.dir.x;
ddy += deriv * wave1.dir.y;
P.y += evaluateWaveSharp(wave2, P.xz, osg_SimulationTime, WaveSharp);
deriv = evaluateWaveDerivSharp(wave2, P.xz, osg_SimulationTime, WaveSharp);
ddx += deriv * wave2.dir.x;
ddy += deriv * wave2.dir.y;
P.y += evaluateWaveSharp(wave3, P.xz, osg_SimulationTime, WaveSharp);
deriv = evaluateWaveDerivSharp(wave3, P.xz, osg_SimulationTime, WaveSharp);
ddx += deriv * wave3.dir.x;
ddy += deriv * wave3.dir.y;
}
void main()
{
const vec4 sca = vec4(0.005, 0.005, 0.005, 0.005);
const vec4 sca2 = vec4(0.02, 0.02, 0.02, 0.02);
const vec4 tscale = vec4(0.25, 0.25, 0.25, 0.25);
mat4 RotationMatrix;
float windEffect = sqrt(WindE*WindE + WindN*WindN) * 0.6;
float windScale = 15.0/(3.0 + windEffect);
float windEffect_low = 0.3 + 0.7 * smoothstep(0.0, 5.0, windEffect);
float waveRoughness = 0.01 + smoothstep(0.0, 40.0, windEffect);
float mixFactor = 0.2 + 0.02 * smoothstep(0.0, 50.0, windEffect);
mixFactor = clamp(mixFactor, 0.3, 0.8);
// sine waves
float ddx, ddx1, ddx2, ddx3, ddy, ddy1, ddy2, ddy3;
float angle;
ddx = 0.0, ddy = 0.0;
ddx1 = 0.0, ddy1 = 0.0;
ddx2 = 0.0, ddy2 = 0.0;
ddx3 = 0.0, ddy3 = 0.0;
// there's no need to do wave patterns or foam for pixels which are so
// far away that we can't actually see them
// we only need detail in the near zone or where the sun reflection is
float dist = length(ecPosition);
bool detailed = (dist < 15000.0)
|| (dot(fg_SunDirection, normalize(ecPosition)) >= 0.7);
if (detailed) {
angle = 0.0;
wave0.freq = WaveFreq ;
wave0.amp = WaveAmp;
wave0.dir = vec2 (0.0, 1.0); //vec2(cos(radians(angle)), sin(radians(angle)));
angle -= 45;
wave1.freq = WaveFreq * 2.0 ;
wave1.amp = WaveAmp * 1.25;
wave1.dir = vec2(0.70710, -0.7071); //vec2(cos(radians(angle)), sin(radians(angle)));
angle += 30;
wave2.freq = WaveFreq * 3.5;
wave2.amp = WaveAmp * 0.75;
wave2.dir = vec2(0.96592, -0.2588);// vec2(cos(radians(angle)), sin(radians(angle)));
angle -= 50;
wave3.freq = WaveFreq * 3.0 ;
wave3.amp = WaveAmp * 0.75;
wave3.dir = vec2(0.42261, -0.9063); //vec2(cos(radians(angle)), sin(radians(angle)));
sumWaves(WaveAngle, -1.5, windScale, WaveFactor, ddx, ddy);
sumWaves(WaveAngle, 1.5, windScale, WaveFactor, ddx1, ddy1);
//reset the waves
angle = 0.0;
float waveamp = WaveAmp * 0.75;
wave0.freq = WaveFreq ;
wave0.amp = waveamp;
wave0.dir = vec2 (0.0, 1.0); //vec2(cos(radians(angle)), sin(radians(angle)));
angle -= 20;
wave1.freq = WaveFreq * 2.0 ;
wave1.amp = waveamp * 1.25;
wave1.dir = vec2(0.93969, -0.34202);// vec2(cos(radians(angle)), sin(radians(angle)));
angle += 35;
wave2.freq = WaveFreq * 3.5;
wave2.amp = waveamp * 0.75;
wave2.dir = vec2(0.965925, 0.25881); //vec2(cos(radians(angle)), sin(radians(angle)));
angle -= 45;
wave3.freq = WaveFreq * 3.0 ;
wave3.amp = waveamp * 0.75;
wave3.dir = vec2(0.866025, -0.5); //vec2(cos(radians(angle)), sin(radians(angle)));
sumWaves(WaveAngle + WaveDAngle, -1.5, windScale, WaveFactor, ddx2, ddy2);
sumWaves(WaveAngle + WaveDAngle, 1.5, windScale, WaveFactor, ddx3, ddy3);
}
vec4 disdis = texture(water_dudvmap, vec2(waterTex2 * tscale)* windScale) * 2.0 - 1.0;
vec3 N0 = vec3(texture(water_normalmap, vec2(waterTex1 + disdis * sca2) * windScale) * 2.0 - 1.0);
vec3 N1 = vec3(texture(perlin_normalmap, vec2(waterTex1 + disdis * sca) * windScale) * 2.0 - 1.0);
N0 += vec3(texture(water_normalmap, vec2(waterTex1 * tscale) * windScale) * 2.0 - 1.0);
N1 += vec3(texture(perlin_normalmap, vec2(waterTex2 * tscale) * windScale) * 2.0 - 1.0);
rotationmatrix(radians(2.0 * sin(osg_SimulationTime * 0.005)), RotationMatrix);
N0 += vec3(texture(water_normalmap, vec2(waterTex2 * RotationMatrix * (tscale + sca2)) * windScale) * 2.0 - 1.0);
N1 += vec3(texture(perlin_normalmap, vec2(waterTex2 * RotationMatrix * (tscale + sca2)) * windScale) * 2.0 - 1.0);
rotationmatrix(radians(-4.0 * sin(osg_SimulationTime * 0.003)), RotationMatrix);
N0 += vec3(texture(water_normalmap, vec2(waterTex1 * RotationMatrix + disdis * sca2) * windScale) * 2.0 - 1.0);
N1 += vec3(texture(perlin_normalmap, vec2(waterTex1 * RotationMatrix + disdis * sca) * windScale) * 2.0 - 1.0);
N0 *= windEffect_low;
N1 *= windEffect_low;
N0.r += (ddx + ddx1 + ddx2 + ddx3);
N0.g += (ddy + ddy1 + ddy2 + ddy3);
vec3 N = normalize(mix(N0, N1, mixFactor) * waveRoughness);
gbuffer1 = encodeNormal(TBN * N);
vec3 floorColor = decodeSRGB(texture(water_colormap, TopoUV).rgb);
gbuffer0.rgb = floorColor;
}

104
Shaders/HDR/geometry-water.vert Normal file
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@ -0,0 +1,104 @@
#version 330 core
layout(location = 0) in vec4 pos;
layout(location = 3) in vec4 multiTexCoord0;
out vec4 waterTex1;
out vec4 waterTex2;
out mat3 TBN;
out vec3 ecPosition;
out vec2 TopoUV;
uniform float WindE, WindN;
uniform float osg_SimulationTime;
uniform mat4 osg_ModelViewMatrix;
uniform mat4 osg_ModelViewProjectionMatrix;
uniform mat4 osg_ViewMatrixInverse;
uniform mat3 osg_NormalMatrix;
// constants for the cartesian to geodetic conversion.
const float a = 6378137.0; //float a = equRad;
const float squash = 0.9966471893352525192801545;
const float latAdjust = 0.9999074159800018; //geotiff source for the depth map
const float lonAdjust = 0.9999537058469516; //actual extents: +-180.008333333333326/+-90.008333333333340
void rotationmatrix(float angle, out mat4 rotmat)
{
rotmat = mat4( cos( angle ), -sin( angle ), 0.0, 0.0,
sin( angle ), cos( angle ), 0.0, 0.0,
0.0 , 0.0 , 1.0, 0.0,
0.0 , 0.0 , 0.0, 1.0 );
}
void main()
{
gl_Position = osg_ModelViewProjectionMatrix * pos;
ecPosition = (osg_ModelViewMatrix * pos).xyz;
// Using precalculated vectors
// vec3 T = normalize(osg_NormalMatrix * tangent);
// vec3 B = normalize(osg_NormalMatrix * binormal);
// vec3 N = normalize(osg_NormalMatrix * normal);
vec3 T = normalize(osg_NormalMatrix * vec3(0.0, -1.0, 0.0));
vec3 B = normalize(osg_NormalMatrix * vec3(1.0, 0.0, 0.0));
vec3 N = normalize(osg_NormalMatrix * vec3(0.0, 0.0, 1.0));
TBN = mat3(T, B, N);
mat4 RotationMatrix;
vec4 t1 = vec4(0.0, osg_SimulationTime * 0.005217, 0.0, 0.0);
vec4 t2 = vec4(0.0, osg_SimulationTime * -0.0012, 0.0, 0.0);
float Angle;
float windFactor = sqrt(WindE * WindE + WindN * WindN) * 0.05;
if (WindN == 0.0 && WindE == 0.0) {
Angle = 0.0;
}else{
Angle = atan(-WindN, WindE) - atan(1.0);
}
rotationmatrix(Angle, RotationMatrix);
waterTex1 = multiTexCoord0 * RotationMatrix - t1 * windFactor;
rotationmatrix(Angle, RotationMatrix);
waterTex2 = multiTexCoord0 * RotationMatrix - t2 * windFactor;
// Geodesy lookup for depth map
vec3 rawPos = (osg_ViewMatrixInverse * vec4(ecPosition, 1.0)).xyz;
float e2 = abs(1.0 - squash * squash);
float ra2 = 1.0/(a * a);
float e4 = e2 * e2;
float XXpYY = rawPos.x * rawPos.x + rawPos.y * rawPos.y;
float Z = rawPos.z;
float sqrtXXpYY = sqrt(XXpYY);
float p = XXpYY * ra2;
float q = Z*Z*(1.0-e2)*ra2;
float r = 1.0/6.0*(p + q - e4);
float s = e4 * p * q/(4.0*r*r*r);
if ( s >= 2.0 && s <= 0.0)
s = 0.0;
float t = pow(1.0+s+sqrt(s*2.0+s*s), 1.0/3.0);
float u = r + r*t + r/t;
float v = sqrt(u*u + e4*q);
float w = (e2*u+ e2*v-e2*q)/(2.0*v);
float k = sqrt(u+v+w*w)-w;
float D = k*sqrtXXpYY/(k+e2);
vec2 NormPosXY = normalize(rawPos.xy);
vec2 NormPosXZ = normalize(vec2(D, rawPos.z));
float signS = sign(rawPos.y);
if (-0.00015 <= rawPos.y && rawPos.y<=.00015)
signS = 1.0;
float signT = sign(rawPos.z);
if (-0.0002 <= rawPos.z && rawPos.z<=.0002)
signT = 1.0;
float cosLon = dot(NormPosXY, vec2(1.0,0.0));
float cosLat = dot(abs(NormPosXZ), vec2(1.0,0.0));
TopoUV.s = signS * lonAdjust * degrees(acos(cosLon))/180.;
TopoUV.t = signT * latAdjust * degrees(acos(cosLat))/90.;
TopoUV.s = TopoUV.s * 0.5 + 0.5;
TopoUV.t = TopoUV.t * 0.5 + 0.5;
}

80
Shaders/HDR/water-lighting.frag Normal file
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@ -0,0 +1,80 @@
#version 330 core
out vec3 fragColor;
in vec2 texCoord;
uniform sampler2D gbuffer0_tex;
uniform sampler2D gbuffer1_tex;
uniform sampler2D depth_tex;
uniform samplerCube prefiltered_envmap;
uniform sampler2D transmittance_lut;
uniform mat4 fg_ViewMatrixInverse;
uniform vec3 fg_SunDirection;
uniform float fg_SunZenithCosTheta;
const float PI = 3.14159265359;
const float RECIPROCAL_PI = 0.31830988618;
const float MAX_PREFILTERED_LOD = 4.0;
const vec3 EXTRATERRESTRIAL_SOLAR_ILLUMINANCE = vec3(128.0);
vec3 decodeNormal(vec2 enc);
vec3 positionFromDepth(vec2 pos, float depth);
vec3 addAerialPerspective(vec3 color, vec2 coord, float depth);
float F_Schlick(float VdotH, float F0)
{
return F0 + (1.0 - F0) * pow(clamp(1.0 - VdotH, 0.0, 1.0), 5.0);
}
float D_GGX(float NdotH, float a2)
{
float f = (NdotH * a2 - NdotH) * NdotH + 1.0;
return a2 / (PI * f * f);
}
void main()
{
float depth = texture(depth_tex, texCoord).r;
vec3 pos = positionFromDepth(texCoord, depth);
vec3 v = normalize(-pos);
vec3 n = decodeNormal(texture(gbuffer1_tex, texCoord).rg);
vec3 l = fg_SunDirection;
vec3 reflected = reflect(-v, n);
vec3 worldNormal = (fg_ViewMatrixInverse * vec4(n, 0.0)).xyz;
vec3 worldReflected = (fg_ViewMatrixInverse * vec4(reflected, 0.0)).xyz;
float NdotL = clamp(dot(n, l), 0.0, 1.0);
float NdotV = clamp(abs(dot(n, v)), 0.001, 1.0);
vec3 h = normalize(v + l);
float NdotH = clamp(dot(n, h), 0.0, 1.0);
// Get transmittance from Sun to the sea surface (assume the water is
// always at sea level, i.e. normalizedAltitude = 0)
vec3 transmittance = texture(transmittance_lut,
vec2(fg_SunZenithCosTheta * 0.5 + 0.5, 0.0)).rgb;
vec3 sunIntensity = EXTRATERRESTRIAL_SOLAR_ILLUMINANCE * transmittance;
const float f0 = 0.02; // For IOR=1.33
float fresnel = F_Schlick(NdotV, f0);
// Refracted light
vec3 seaColor = texture(gbuffer0_tex, texCoord).rgb;
vec3 Esky = textureLod(prefiltered_envmap, worldNormal, MAX_PREFILTERED_LOD).rgb;
vec3 refracted = seaColor * Esky * RECIPROCAL_PI;
// Reflected sky light
vec3 reflection = textureLod(prefiltered_envmap, worldReflected, 1.0).rgb;
vec3 color = mix(refracted, reflection, fresnel);
// Add reflected Sun light
color += RECIPROCAL_PI * fresnel * D_GGX(NdotH, 0.001) * sunIntensity * NdotL;
color = addAerialPerspective(color, texCoord, length(pos));
fragColor = color;
}