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ALS fake aircraft shadow technique based on projecting a duplicate model

This commit is contained in:
Thorsten Renk 2015-03-05 10:01:28 +02:00
parent 4d94d42ff6
commit 76206b88a0
2 changed files with 470 additions and 0 deletions

370
Effects/shadow-vol.eff Normal file
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<?xml version="1.0" encoding="utf-8"?>
<PropertyList>
<name>Effects/shadow</name>
<!-- <inherits-from>Effects/shadow</inherits-from> -->
<parameters>
<texture n ="0">
<type>white</type>
</texture>
<vertex-program-two-side type="bool">false</vertex-program-two-side>
<material>
<color-mode-uniform>1</color-mode-uniform>
<!-- DIFFUSE -->
</material>
<material-id>0</material-id>
<!-- BEGIN fog include -->
<visibility><use>/environment/ground-visibility-m</use></visibility>
<avisibility><use>/environment/visibility-m</use></avisibility>
<lthickness><use>/environment/ground-haze-thickness-m</use></lthickness>
<scattering><use>/rendering/scene/scattering</use></scattering>
<ground_scattering><use>/environment/surface/scattering</use></ground_scattering>
<terminator><use>/environment/terminator-relative-position-m</use></terminator>
<terrain_alt><use>/environment/mean-terrain-elevation-m</use></terrain_alt>
<overcast><use>/rendering/scene/overcast</use></overcast>
<eye_alt><use>/sim/rendering/eye-altitude-m</use></eye_alt>
<cloud_self_shading><use>/environment/cloud-self-shading</use></cloud_self_shading>
<moonlight><use>/environment/moonlight</use></moonlight>
<alt_agl><use>/position/altitude-agl-m</use></alt_agl>
<model-pitch><use>/orientation/model/pitch-deg</use></model-pitch>
<model-roll><use>/orientation/model/roll-deg</use></model-roll>
<gear_clearance>0.5</gear_clearance>
<!-- END fog include -->
</parameters>
<technique n="5">
<predicate>
<and>
<property>/sim/rendering/shaders/skydome</property>
<or>
<less-equal>
<value type="float">2.0</value>
<glversion/>
</less-equal>
<and>
<extension-supported>GL_ARB_shader_objects</extension-supported>
<extension-supported>GL_ARB_shading_language_100</extension-supported>
<extension-supported>GL_ARB_vertex_shader</extension-supported>
<extension-supported>GL_ARB_fragment_shader</extension-supported>
</and>
</or>
</and>
</predicate>
<!-- first pass so that the depth buffer is filled, we then render only the uppermost
layer of the projected shadow volume in the second pass to avod drawing multiple
transparent layers on top of each other-->
<pass>
<lighting>true</lighting>
<material>
<active><use>material/active</use></active>
<ambient><use>material/ambient</use></ambient>
<diffuse><use>material/diffuse</use></diffuse>
<specular><use>material/specular</use></specular>
<emissive><use>material/emissive</use></emissive>
<shininess><use>material/shininess</use></shininess>
<color-mode><use>material/color-mode</use></color-mode>
</material>
<blend>
<active><use>blend/active</use></active>
<source><use>blend/source</use></source>
<destination><use>blend/destination</use></destination>
</blend>
<shade-model><use>shade-model</use></shade-model>
<cull-face><use>cull-face</use></cull-face>
<render-bin>
<bin-number>10</bin-number>
<bin-name>DepthSortedBin</bin-name>
</render-bin>
<rendering-hint><use>rendering-hint</use></rendering-hint>
<texture-unit>
<unit>0</unit>
<type><use>texture[0]/type</use></type>
<image><use>texture[0]/image</use></image>
<filter><use>texture[0]/filter</use></filter>
<wrap-s><use>texture[0]/wrap-s</use></wrap-s>
<wrap-t><use>texture[0]/wrap-t</use></wrap-t>
</texture-unit>
<program>
<vertex-shader>Shaders/shadow-vol-ALS.vert</vertex-shader>
<fragment-shader>Shaders/trivial.frag</fragment-shader>
</program>
<uniform>
<name>hazeLayerAltitude</name>
<type>float</type>
<value><use>lthickness</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>ground_scattering</name>
<type>float</type>
<value><use>ground_scattering</use></value>
</uniform>
<uniform>
<name>terrain_alt</name>
<type>float</type>
<value><use>terrain_alt</use></value>
</uniform>
<uniform>
<name>overcast</name>
<type>float</type>
<value><use>overcast</use></value>
</uniform>
<uniform>
<name>eye_alt</name>
<type>float</type>
<value><use>eye_alt</use></value>
</uniform>
<uniform>
<name>moonlight</name>
<type>float</type>
<value><use>moonlight</use></value>
</uniform>
<uniform>
<name>alt_agl</name>
<type>float</type>
<value><use>alt_agl</use></value>
</uniform>
<uniform>
<name>pitch</name>
<type>float</type>
<value><use>model-pitch</use></value>
</uniform>
<uniform>
<name>roll</name>
<type>float</type>
<value><use>model-roll</use></value>
</uniform>
<uniform>
<name>gear_clearance</name>
<type>float</type>
<value><use>gear_clearance</use></value>
</uniform>
<depth>
<function>lequal</function>
<write-mask type="bool">true</write-mask>
</depth>
<color-mask type="vec4d">0 0 0 0</color-mask>
</pass>
<pass>
<lighting>true</lighting>
<material>
<active><use>material/active</use></active>
<ambient><use>material/ambient</use></ambient>
<diffuse><use>material/diffuse</use></diffuse>
<specular><use>material/specular</use></specular>
<emissive><use>material/emissive</use></emissive>
<shininess><use>material/shininess</use></shininess>
<color-mode><use>material/color-mode</use></color-mode>
</material>
<blend>
<active><use>blend/active</use></active>
<source><use>blend/source</use></source>
<destination><use>blend/destination</use></destination>
</blend>
<shade-model><use>shade-model</use></shade-model>
<cull-face>back</cull-face>
<render-bin>
<bin-number>10</bin-number>
<bin-name>DepthSortedBin</bin-name>
</render-bin>
<rendering-hint><use>rendering-hint</use></rendering-hint>
<texture-unit>
<!-- The texture unit is always active because the shaders expect
that. -->
<unit>0</unit>
<!-- If there is a texture, the type in the derived effect
will be "2d". -->
<type><use>texture[0]/type</use></type>
<image><use>texture[0]/image</use></image>
<filter><use>texture[0]/filter</use></filter>
<wrap-s><use>texture[0]/wrap-s</use></wrap-s>
<wrap-t><use>texture[0]/wrap-t</use></wrap-t>
<!--
<internal-format>
<use>texture[0]/internal-format</use>
</internal-format>
-->
</texture-unit>
<!--<alpha-to-coverage>true</alpha-to-coverage>-->
<!--<vertex-program-two-side>
<use>vertex-program-two-side</use>
</vertex-program-two-side>-->
<program>
<vertex-shader>Shaders/shadow-vol-ALS.vert</vertex-shader>
<fragment-shader>Shaders/shadow-ALS.frag</fragment-shader>
</program>
<uniform>
<name>visibility</name>
<type>float</type>
<value><use>visibility</use></value>
</uniform>
<uniform>
<name>avisibility</name>
<type>float</type>
<value><use>avisibility</use></value>
</uniform>
<uniform>
<name>hazeLayerAltitude</name>
<type>float</type>
<value><use>lthickness</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>ground_scattering</name>
<type>float</type>
<value><use>ground_scattering</use></value>
</uniform>
<uniform>
<name>terrain_alt</name>
<type>float</type>
<value><use>terrain_alt</use></value>
</uniform>
<uniform>
<name>overcast</name>
<type>float</type>
<value><use>overcast</use></value>
</uniform>
<uniform>
<name>eye_alt</name>
<type>float</type>
<value><use>eye_alt</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>alt_agl</name>
<type>float</type>
<value><use>alt_agl</use></value>
</uniform>
<uniform>
<name>pitch</name>
<type>float</type>
<value><use>model-pitch</use></value>
</uniform>
<uniform>
<name>roll</name>
<type>float</type>
<value><use>model-roll</use></value>
</uniform>
<uniform>
<name>gear_clearance</name>
<type>float</type>
<value><use>gear_clearance</use></value>
</uniform>
<depth>
<function>equal</function>
<write-mask type="bool">true</write-mask>
</depth>
</pass>
</technique>
<technique n="13">
<pass>
<lighting>true</lighting>
<material>
<active>
<use>material/active</use>
</active>
<ambient>
<use>material/ambient</use>
</ambient>
<diffuse>
<use>material/diffuse</use>
</diffuse>
<specular>
<use>material/specular</use>
</specular>
<emissive>
<use>material/emissive</use>
</emissive>
<shininess>
<use>material/shininess</use>
</shininess>
<color-mode>
<use>material/color-mode</use>
</color-mode>
</material>
<blend>
<active>
<use>blend/active</use>
</active>
<source>
<use>blend/source</use>
</source>
<destination>
<use>blend/destination</use>
</destination>
</blend>
<shade-model>
<use>shade-model</use>
</shade-model>
<cull-face>
<use>cull-face</use>
</cull-face>
<rendering-hint>
<use>rendering-hint</use>
</rendering-hint>
<texture-unit>
<active>
<use>texture[0]/active</use>
</active>
<unit>0</unit>
<image>
<use>texture[0]/image</use>
</image>
<type>
<use>texture[0]/type</use>
</type>
<filter>
<use>texture[0]/filter</use>
</filter>
<wrap-s>
<use>texture[0]/wrap-s</use>
</wrap-s>
<wrap-t>
<use>texture[0]/wrap-t</use>
</wrap-t>
<!--
<internal-format>
<use>texture[0]/internal-format</use>
</internal-format>
-->
<environment>
<mode>modulate</mode>
</environment>
</texture-unit>
<!-- A two-sided lighting model is set by default near the root
of the scene graph. Perhaps that ought to be set in this
effect?
-->
</pass>
</technique>
</PropertyList>

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Shaders/shadow-vol-ALS.vert Normal file
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// -*-C++-*-
#version 120
uniform float hazeLayerAltitude;
uniform float terminator;
uniform float terrain_alt;
uniform float overcast;
uniform float ground_scattering;
uniform float eye_alt;
uniform float moonlight;
uniform float alt_agl;
uniform float pitch;
uniform float roll;
uniform float gear_clearance;
const float EarthRadius = 5800000.0;
const float terminator_width = 200000.0;
void rotationMatrixPR(in float sinRx, in float cosRx, in float sinRy, in float cosRy, out mat4 rotmat)
{
rotmat = mat4( cosRy , sinRx * sinRy , cosRx * sinRy, 0.0,
0.0 , cosRx , -sinRx * cosRx, 0.0,
-sinRy, sinRx * cosRy, cosRx * cosRy , 0.0,
0.0 , 0.0 , 0.0 , 1.0 );
}
float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
{
if (x < -15.0) {return 0.0;}
return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
}
void main()
{
gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
vec3 relPos = gl_Vertex.xyz - ep.xyz;
// compute the strength of light
float vertex_alt = max(gl_Vertex.z,100.0);
float scattering = ground_scattering + (1.0 - ground_scattering) * smoothstep(hazeLayerAltitude -100.0, hazeLayerAltitude + 100.0, vertex_alt);
vec3 lightFull = (gl_ModelViewMatrixInverse * gl_LightSource[0].position).xyz;
vec3 lightHorizon = normalize(vec3(lightFull.x,lightFull.y, 0.0));
float yprime = -dot(relPos, lightHorizon);
float yprime_alt = yprime - sqrt(2.0 * EarthRadius * vertex_alt);
float earthShade = 0.6 * (1.0 - smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt)) + 0.4;
float lightArg = (terminator-yprime_alt)/100000.0;
vec4 light_diffuse;
light_diffuse.b = light_func(lightArg, 1.330e-05, 0.264, 3.827, 1.08e-05, 1.0);
light_diffuse.g = light_func(lightArg, 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 = light_diffuse * scattering;
float shade_depth = 1.0 * smoothstep (0.6,0.95,ground_scattering) * (1.0-smoothstep(0.1,0.5,overcast)) * smoothstep(0.4,1.5,earthShade);
light_diffuse.rgb = light_diffuse.rgb * (1.0 + 1.2 * shade_depth);
//prepare rotation matrix
mat4 RotMatPR;
float _roll = roll;
if (_roll>90.0 || _roll < -90.0)
{_roll = -_roll;}
float cosRx = cos(radians(_roll));
float sinRx = sin(radians(_roll));
float cosRy = cos(radians(-pitch));
float sinRy = sin(radians(-pitch));
rotationMatrixPR(sinRx, cosRx, sinRy, cosRy, RotMatPR);
// project the shadow onto the ground
vec4 vertex = RotMatPR * gl_Vertex;
vec4 pos = vertex;
pos.z = -0.9* alt_agl + 0.05 * vertex.z;
//pos.z = 0.05 * (vertex.z + gear_clearance);
// pos.z = pos.z - offset;
pos.xy -= lightFull.xy * 0.95* (alt_agl + vertex.z + gear_clearance)/lightFull.z;
gl_Position = gl_ModelViewProjectionMatrix * pos;
gl_FrontColor = light_diffuse;
gl_BackColor = gl_FrontColor;
}