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ALS: New cloud rendering detail level with more dramatic Mie scattering at cloud fringes done inside fragment shader

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This commit is contained in:
Thorsten Renk 2018-08-30 09:17:36 +03:00
parent 853e5ea6c5
commit cce0fac2f8
5 changed files with 587 additions and 0 deletions
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183
Effects/cloud.eff
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@ -29,6 +29,189 @@
<display_ysize><use>/sim/startup/ysize</use></display_ysize>
</parameters>
<technique n="8">
<predicate>
<and>
<property>/sim/rendering/shaders/skydome</property>
<less-equal>
<value type="float">1.0</value>
<shader-language/>
</less-equal>
<less-equal>
<value type="float">1.0</value>
<float-property>/sim/rendering/shaders/clouds</float-property>
</less-equal>
</and>
</predicate>
<pass n="0">
<!-- This is apparently not used, so maybe we'll blow it way soon. -->
<lighting>true</lighting>
<material>
<ambient type="vec4d">0.5 0.5 0.5 1.0</ambient>
<diffuse type="vec4d">0.5 0.5 0.5 1.0</diffuse>
<color-mode>off</color-mode>
</material>
<alpha-test>
<comparison>greater</comparison>
<reference type="float">0.01</reference>
</alpha-test>
<shade-model>smooth</shade-model>
<blend>
<source>src-alpha</source>
<destination>one-minus-src-alpha</destination>
</blend>
<depth>
<write-mask>false</write-mask>
</depth>
<render-bin>
<bin-number>10</bin-number>
<bin-name>DepthSortedBin</bin-name>
</render-bin>
<texture-unit>
<unit>0</unit>
<type>2d</type>
<image><use>texture[0]/image</use></image>
<wrap-s>clamp</wrap-s>
<wrap-t>clamp</wrap-t>
</texture-unit>
<program>
<vertex-shader>Shaders/3dcloud-ALS-detailed.vert</vertex-shader>
<fragment-shader>Shaders/3dcloud-ALS-detailed.frag</fragment-shader>
<fragment-shader>Shaders/filters-ALS.frag</fragment-shader>
<fragment-shader>Shaders/noise.frag</fragment-shader>
<attribute>
<name>usrAttr1</name>
<index>10</index>
</attribute>
<attribute>
<name>usrAttr2</name>
<index>11</index>
</attribute>
</program>
<uniform>
<name>baseTexture</name>
<type>sampler-2d</type>
<value type="int">0</value>
</uniform>
<uniform>
<name>range</name>
<type>float</type>
<value><use>range</use></value>
</uniform>
<uniform>
<name>detail_range</name>
<type>float</type>
<value><use>detail</use></value>
</uniform>
<uniform>
<name>scattering</name>
<type>float</type>
<value><use>scattering</use></value>
</uniform>
<uniform>
<name>terminator</name>
<type>float</type>
<value><use>terminator</use></value>
</uniform>
<uniform>
<name>altitude</name>
<type>float</type>
<value><use>altitude</use></value>
</uniform>
<uniform>
<name>cloud_self_shading</name>
<type>float</type>
<value><use>cloud_self_shading</use></value>
</uniform>
<uniform>
<name>moonlight</name>
<type>float</type>
<value><use>moonlight</use></value>
</uniform>
<uniform>
<name>air_pollution</name>
<type>float</type>
<value><use>air_pollution</use></value>
</uniform>
<uniform>
<name>visibility</name>
<type>float</type>
<value><use>visibility</use></value>
</uniform>
<uniform>
<name>flash</name>
<type>float</type>
<value><use>flash</use></value>
</uniform>
<uniform>
<name>lightning_pos_x</name>
<type>float</type>
<value><use>lightning-pos-x</use></value>
</uniform>
<uniform>
<name>lightning_pos_y</name>
<type>float</type>
<value><use>lightning-pos-y</use></value>
</uniform>
<uniform>
<name>lightning_range</name>
<type>float</type>
<value><use>lightning-range</use></value>
</uniform>
<uniform>
<name>gamma</name>
<type>float</type>
<value><use>gamma</use></value>
</uniform>
<uniform>
<name>brightness</name>
<type>float</type>
<value><use>brightness</use></value>
</uniform>
<uniform>
<name>use_filtering</name>
<type>bool</type>
<value><use>use_filtering</use></value>
</uniform>
<uniform>
<name>use_night_vision</name>
<type>bool</type>
<value><use>use_night_vision</use></value>
</uniform>
<uniform>
<name>use_IR_vision</name>
<type>bool</type>
<value><use>use_IR_vision</use></value>
</uniform>
<uniform>
<name>delta_T</name>
<type>float</type>
<value><use>delta_T</use></value>
</uniform>
<uniform>
<name>fact_grey</name>
<type>float</type>
<value><use>fact_grey</use></value>
</uniform>
<uniform>
<name>fact_black</name>
<type>float</type>
<value><use>fact_black</use></value>
</uniform>
<uniform>
<name>display_xsize</name>
<type>int</type>
<value><use>display_xsize</use></value>
</uniform>
<uniform>
<name>display_ysize</name>
<type>int</type>
<value><use>display_ysize</use></value>
</uniform>
<!--<vertex-program-two-side>true</vertex-program-two-side>-->
</pass>
</technique>
<technique n="9">
<predicate>
<and>

84
Shaders/3dcloud-ALS-detailed.frag Normal file
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@ -0,0 +1,84 @@
#version 120
uniform sampler2D baseTexture;
uniform float scattering;
varying float fogFactor;
varying float mie_frag;
varying float mie_frag_mod;
varying float z_pos;
varying float bottom_shade;
varying vec3 internal_pos;
varying vec3 hazeColor;
vec3 filter_combined (in vec3 color) ;
void main(void)
{
vec4 base = texture2D( baseTexture, gl_TexCoord[0].st);
if (base.a < 0.02)
discard;
float mie_factor = 0.0;
float geo_factor = 1.0;
float mie_sign = 1.0;
if (mie_frag < 0.0) {mie_sign = -1.0;}
if (mie_sign > 0.0)
{mie_factor = smoothstep(0.8, 1.0, mie_frag);}
else
{mie_factor = -1.0 * (1.0 - smoothstep(-1.0, -0.8, mie_frag));}
mie_factor *= mie_frag_mod;
// suppress effect in cloud center
float z_bias = 0.2 * (1.0 - smoothstep(2.0, 3.0, z_pos));
geo_factor *= smoothstep(-0.9 - z_bias, -0.4 - z_bias, internal_pos.x) * (1.0 -smoothstep(0.4 + z_bias, 0.9 + z_bias, internal_pos.x));
geo_factor *= smoothstep(-0.9 - z_bias, -0.4 - z_bias, internal_pos.y) * (1.0 -smoothstep(0.4 + z_bias, 0.9 + z_bias, internal_pos.y));
geo_factor *= smoothstep(0, 0.3, internal_pos.z) * (1.0 - smoothstep(0.5, 1.2, internal_pos.z));
if (mie_sign > 0.0)
{
mie_factor *=(1.0 -geo_factor);
}
float transparency = smoothstep(0.0, 0.7, base.a);
float opacity = smoothstep(0.7, 1.0, base.a);
float inverse_mie = 0.0;
if ((opacity == 0.0) && (mie_sign > 0.0)) // Mie forward scattering enhancing light
{mie_factor *= (1.0 - pow(transparency, 2.0));}
else if ((opacity == 0.0) && (mie_sign < 0.0)) // Mie forward scattering reducing reflected light
{
inverse_mie = (1.0 - pow(transparency, 2.0)) * smoothstep(0.65, 0.8, scattering);
inverse_mie *= (1.0 - smoothstep(-1.0, -0.5, mie_frag));
}
else if (mie_sign > 0.0) // bulk light absorption
{mie_factor *= - 4.0 * pow(opacity, 2.0);}
// darken the bulk of the away-facing cloud
float bulk_shade_factor = (1.0 - 0.6 * geo_factor * smoothstep(0.5, 1.0, mie_frag));
bulk_shade_factor -= 0.3 * smoothstep(0.5, 1.0, mie_frag) * (1.0 - mie_frag_mod) * (1.0 - smoothstep(0.4, 0.5, bottom_shade));
float mie_enhancement = 1.0 + clamp(mie_factor, 0.0, 1.0);
mie_enhancement = mie_enhancement * bulk_shade_factor;
vec4 finalColor = base * gl_Color;
finalColor.rgb *= mie_enhancement * (1.0 - 0.4 * inverse_mie);
finalColor.rgb = max(finalColor.rgb, gl_Color.rgb * 1.2 * bottom_shade);
finalColor.rgb = mix(hazeColor, finalColor.rgb, fogFactor );
finalColor.rgb = filter_combined(finalColor.rgb);
gl_FragColor.rgb = finalColor.rgb;
gl_FragColor.a = mix(0.0, finalColor.a, 1.0 - 0.5 * (1.0 - fogFactor));
}

293
Shaders/3dcloud-ALS-detailed.vert Normal file
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@ -0,0 +1,293 @@
// -*-C++-*-
#version 120
varying float fogFactor;
varying vec3 hazeColor;
varying float mie_frag;
varying float mie_frag_mod;
varying vec3 internal_pos;
varying float bottom_shade;
varying float z_pos;
uniform float range; // From /sim/rendering/clouds3d-vis-range
uniform float detail_range; // From /sim/rendering/clouds3d_detail-range
uniform float scattering;
uniform float terminator;
uniform float altitude;
uniform float cloud_self_shading;
uniform float visibility;
uniform float moonlight;
uniform float air_pollution;
uniform float flash;
uniform float lightning_pos_x;
uniform float lightning_pos_y;
uniform float lightning_range;
attribute vec3 usrAttr1;
attribute vec3 usrAttr2;
float alpha_factor = usrAttr1.r;
float shade_factor = usrAttr1.g;
float cloud_height = usrAttr1.b;
float bottom_factor = usrAttr2.r;
float middle_factor = usrAttr2.g;
float top_factor = usrAttr2.b;
const float EarthRadius = 5800000.0;
// light_func is a generalized logistic function fit to the light intensity as a function
// of scaled terminator position obtained from Flightgear core
float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
{
x = x-0.5;
// use the asymptotics to shorten computations
if (x > 30.0) {return e;}
if (x < -15.0) {return 0.03;}
return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
}
float mie_func (in float x, in float Mie)
{
return x + 2.0 * x * Mie * (1.0 -0.8*x) * (1.0 -0.8*x);
}
void main(void)
{
//shade_factor = shade_factor * cloud_self_shading;
//top_factor = top_factor * cloud_self_shading;
//shade_factor = min(shade_factor, top_factor);
//middle_factor = min(middle_factor, top_factor);
//bottom_factor = min(bottom_factor, top_factor);
float intensity;
float mix_factor;
bottom_shade = bottom_factor;
vec3 shadedFogColor = vec3(0.55, 0.67, 0.88);
vec3 moonLightColor = vec3 (0.095, 0.095, 0.15) * moonlight * scattering;
gl_TexCoord[0] = gl_MultiTexCoord0;
vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
vec4 l = gl_ModelViewMatrixInverse * vec4(0.0,0.0,1.0,1.0);
vec3 u = normalize(ep.xyz - l.xyz);
// Find a rotation matrix that rotates 1,0,0 into u. u, r and w are
// the columns of that matrix.
vec3 absu = abs(u);
vec3 r = normalize(vec3(-u.y, u.x, 0.0));
vec3 w = cross(u, r);
// Do the matrix multiplication by [ u r w pos]. Assume no
// scaling in the homogeneous component of pos.
gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
gl_Position.xyz = gl_Vertex.x * u;
gl_Position.xyz += gl_Vertex.y * r;
gl_Position.xyz += gl_Vertex.z * w;
// Apply Z scaling to allow sprites to be squashed in the z-axis
gl_Position.z = gl_Position.z * gl_Color.w;
// Now shift the sprite to the correct position in the cloud.
gl_Position.xyz += gl_Color.xyz;
internal_pos = gl_Position.xyz/ cloud_height;
// Determine a lighting normal based on the vertex position from the
// center of the cloud, so that sprite on the opposite side of the cloud to the sun are darker.
float n = dot(normalize(-gl_LightSource[0].position.xyz),
normalize(vec3(gl_ModelViewMatrix * vec4(- gl_Position.x, - gl_Position.y, - gl_Position.z, 0.0))));
// prepare suppression of shadeward Mie terms
float n1 = dot(normalize(-gl_LightSource[0].position.xyz),
normalize(vec3(gl_ModelViewMatrix * vec4(- gl_Color.x, - gl_Color.y, - gl_Color.z, 0.0))));
//z_pos = dot(normalize(-gl_LightSource[0].position.xyz),
// vec3(gl_ModelViewMatrix * vec4(- gl_Position.x, - gl_Position.y, - gl_Position.z, 0.0)))/cloud_height;
float mie_suppress = smoothstep(0.0, 0.3, n1);
// Determine the position - used for fog and shading calculations
float fogCoord = length(vec3(gl_ModelViewMatrix * vec4(gl_Color.x, gl_Color.y, gl_Color.z, 1.0)));
float center_dist = length(vec3(gl_ModelViewMatrix * vec4(0.0,0.0,0.0,1.0)));
z_pos = (fogCoord - center_dist)/cloud_height;
if ((fogCoord > detail_range) && (fogCoord > center_dist) && (shade_factor < 0.7)) {
// More than detail_range away, so discard all sprites on opposite side of
// cloud center by shifting them beyond the view fustrum
gl_Position = vec4(0.0,0.0,10.0,1.0);
gl_FrontColor.a = 0.0;
} else {
// Determine the shading of the vertex. We shade it based on it's position
// in the cloud relative to the sun, and it's vertical position in the cloud.
float shade = mix(shade_factor, top_factor, smoothstep(-0.3, 0.3, n));
//if (n < 0) {
// shade = mix(top_factor, shade_factor, abs(n));
//}
if (gl_Position.z < 0.5 * cloud_height) {
shade = min(shade, mix(bottom_factor, middle_factor, gl_Position.z * 2.0 / cloud_height));
} else {
shade = min(shade, mix(middle_factor, top_factor, gl_Position.z * 2.0 / cloud_height - 1.0));
}
//float h = gl_Position.z / cloud_height;
//if (h < 0.5) {
// shade = min(shade, mix(bottom_factor, middle_factor, smoothstep(0.0, 0.5, h)));
//} else {
// shade = min(shade, mix(middle_factor, top_factor, smoothstep(2.0 * (h - 0.5)));
// }
// Final position of the sprite
vec3 relVector = gl_Position.xyz - ep.xyz;
gl_Position = gl_ModelViewProjectionMatrix * gl_Position;
// Light at the final position
// first obtain normal to sun position
vec3 lightFull = (gl_ModelViewMatrixInverse * gl_LightSource[0].position).xyz;
vec3 lightHorizon = normalize(vec3(lightFull.x,lightFull.y, 0.0));
// yprime is the distance of the vertex into sun direction, corrected for altitude
// the altitude correction is clamped to reasonable values, sometimes altitude isn't parsed correctly, leading
// to overbright or overdark clouds
// float vertex_alt = clamp(altitude * 0.30480 + relVector.z,1000.0,10000.0);
float vertex_alt = clamp(altitude + relVector.z, 300.0, 10000.0);
float yprime = -dot(relVector, lightHorizon);
float yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
// two times terminator width governs how quickly light fades into shadow
float terminator_width = 200000.0;
float earthShade = 1.0- 0.9* smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt);
float earthShadeFactor = 1.0 - smoothstep(0.4, 0.5, earthShade);
// compute the light at the position
vec4 light_diffuse;
float lightArg = (terminator-yprime_alt)/100000.0;
light_diffuse.b = light_func(lightArg -1.2 * air_pollution, 1.330e-05, 0.264, 2.227, 1.08e-05, 1.0);
light_diffuse.g = light_func(lightArg -0.6 * air_pollution, 3.931e-06, 0.264, 3.827, 7.93e-06, 1.0);
light_diffuse.r = light_func(lightArg, 8.305e-06, 0.161, 3.827, 3.04e-05, 1.0);
light_diffuse.a = 1.0;
//light_diffuse *= cloud_self_shading;
intensity = (1.0 - (0.8 * (1.0 - earthShade))) * length(light_diffuse.rgb);
light_diffuse.rgb = intensity * normalize(mix(light_diffuse.rgb, shadedFogColor, (1.0 - smoothstep(0.5,0.9, min(scattering, cloud_self_shading) ))));
// correct ambient light intensity and hue before sunrise
if (earthShade < 0.6)
{
light_diffuse.rgb = intensity * normalize(mix(light_diffuse.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.6,earthShade ) ));
}
gl_FrontColor.rgb = intensity * shade * normalize(mix(light_diffuse.rgb, shadedFogColor, smoothstep(0.1,0.4, (1.0 - shade) ))) ;
// lightning
vec2 lightningRelVector = relVector.xy - vec2(lightning_pos_x, lightning_pos_y);
float rCoord = length(lightningRelVector);
vec3 flash_color = vec3 (0.43, 0.57, 1.0);
float flash_factor = flash;
if (flash == 2)
{
flash_color = vec3 (0.8, 0.7, 0.4);
flash_factor = 1;
}
float rn = 0.5 + 0.5 * fract(gl_Color.x);
gl_FrontColor.rgb += flash_factor * flash_color * (1.0 - smoothstep(lightning_range, 5.0 * lightning_range, rCoord)) * rn;
// fading of cloudlets
if ((fogCoord > (0.9 * detail_range)) && (fogCoord > center_dist) && (shade_factor < 0.7)) {
// cloudlet is almost at the detail range, so fade it out.
gl_FrontColor.a = 1.0 - smoothstep(0.9 * detail_range, detail_range, fogCoord);
} else {
// As we get within 100m of the sprite, it is faded out. Equally at large distances it also fades out.
gl_FrontColor.a = min(smoothstep(10.0, 100.0, fogCoord), 1.0 - smoothstep(0.9 * range, range, fogCoord));
}
gl_FrontColor.a = gl_FrontColor.a * (1.0 - smoothstep(visibility, 3.0* visibility, fogCoord));
fogFactor = exp(-fogCoord/visibility);
// haze of ground haze shader is slightly bluish
hazeColor = light_diffuse.rgb;
hazeColor.r = hazeColor.r * 0.83;
hazeColor.g = hazeColor.g * 0.9;
hazeColor = hazeColor * scattering;
// Mie correction
float Mie = 0.0;
float MieFactor = dot(normalize(lightFull), normalize(relVector));
mie_frag = MieFactor;
mie_frag_mod = mie_suppress * (1.0 - smoothstep(0.4, 0.6, bottom_factor)) * (1.0 - smoothstep(detail_range, 1.5 * detail_range, fogCoord)) * smoothstep(0.65, 0.8, scattering)
* smoothstep(0.7, 1.0, top_factor);
if (bottom_factor < 0.4) {mie_frag_mod = 0.0;}
if (bottom_factor > 0.4)
{
MieFactor = dot(normalize(lightFull), normalize(relVector));
Mie = 1.5 * smoothstep(0.9,1.0, MieFactor) * smoothstep(0.6, 0.8, bottom_factor) * (1.0-earthShadeFactor) ;
//if (MieFactor < 0.0) {Mie = - Mie;}
}
//else {Mie = 0.0;}
if (Mie > 0.0)
{
hazeColor.r = mie_func(hazeColor.r, Mie);
hazeColor.g = mie_func(hazeColor.g, 0.8* Mie);
hazeColor.b = mie_func(hazeColor.b, 0.5* Mie);
gl_FrontColor.r = mie_func(gl_FrontColor.r, Mie);
gl_FrontColor.g = mie_func(gl_FrontColor.g, 0.8* Mie);
gl_FrontColor.b = mie_func(gl_FrontColor.b, 0.5*Mie);
}
else if (MieFactor < 0.0)
{
float thickness_reduction = smoothstep(0.4, 0.8, bottom_factor) ;
float light_reduction = dot (lightFull, lightHorizon);
light_reduction *= light_reduction;
float factor_b = 0.8 + 0.2 * (1.0 - smoothstep(0.0, 0.7, -MieFactor) * thickness_reduction * light_reduction) ;
float factor_r = 0.6 + 0.4 * (1.0 - smoothstep(0.0, 0.7, -MieFactor) * thickness_reduction * light_reduction) ;
float factor_g = 0.65 + 0.35 * (1.0 - smoothstep(0.0, 0.7, -MieFactor) * thickness_reduction * light_reduction) ;
hazeColor.r *= factor_r;
hazeColor.g *= factor_g;
hazeColor.b *= factor_b;
gl_FrontColor.r *= factor_r;
gl_FrontColor.g *= factor_g;
gl_FrontColor.b *= factor_b;
}
gl_FrontColor.rgb = gl_FrontColor.rgb + moonLightColor * earthShadeFactor;
hazeColor.rgb = hazeColor.rgb + moonLightColor * earthShadeFactor;
gl_FrontColor.a = gl_FrontColor.a * alpha_factor;
gl_BackColor = gl_FrontColor;
}
}

1
defaults.xml
View file

@ -128,6 +128,7 @@ Started September 2000 by David Megginson, david@megginson.com
<filtering type="int">8</filtering>
<shaders>
<custom-settings type="bool" userarchive="y">false</custom-settings>
<clouds type="float" userarchive="y">0.0</clouds>
<generic type="float" userarchive="y">1.0</generic>
<landmass type="float" userarchive="y">1.0</landmass>
<model type="float" userarchive="y">1.0</model>

26
gui/dialogs/shaders-lightfield.xml
View file

@ -45,6 +45,32 @@
</hrule>
</group>
<group>
<layout>hbox</layout>
<halign>right</halign>
<text>
<halign>left</halign>
<label>Clouds</label>
</text>
<slider>
<name>cloud</name>
<min>0.0</min>
<max>1.0</max>
<step>1.0</step>
<fraction>0.17</fraction>
<live>true</live>
<property>/sim/rendering/shaders/clouds</property>
<binding>
<command>dialog-apply</command>
<object-name>cloud</object-name>
</binding>
</slider>
<empty>
<pref-width>55</pref-width>
</empty>
</group>
<group>
<layout>hbox</layout>
<halign>right</halign>