Add Skydome effect.
Signed-off-by: Vivian Meazza <vivian.meazza@lineone.net>
This commit is contained in:
Vivian Meazza
parent
3825563122
commit
c67632905a
4 changed files with 855 additions and 442 deletions
64
Effects/skydome.eff
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64
Effects/skydome.eff
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<?xml version="1.0" encoding="utf-8"?>
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<PropertyList>
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<name>Effects/skydome</name>
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<parameters>
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<mie><use>/sim/rendering/mie</use></mie>
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<rayleigh><use>/sim/rendering/rayleigh</use></rayleigh>
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<density><use>/sim/rendering/dome-density</use></density>
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</parameters>
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<technique n="8">
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<predicate>
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<and>
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<property>/sim/rendering/shader-effects</property>
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<property>/sim/rendering/scattering-shader</property>
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<or>
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<less-equal>
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<value type="float">2.0</value>
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<glversion/>
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</less-equal>
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<and>
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<extension-supported>GL_ARB_shader_objects</extension-supported>
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<extension-supported>GL_ARB_shading_language_100</extension-supported>
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<extension-supported>GL_ARB_vertex_shader</extension-supported>
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<extension-supported>GL_ARB_fragment_shader</extension-supported>
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</and>
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</or>
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</and>
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</predicate>
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<pass>
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<lighting>true</lighting>
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<shade-model>smooth</shade-model>
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<cull-face>back</cull-face>
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<program>
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<vertex-shader>Shaders/skydome.vert</vertex-shader>
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<fragment-shader>Shaders/skydome.frag</fragment-shader>
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</program>
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<uniform>
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<name>mK</name>
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<type>float</type>
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<value><use>mie</use></value>
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</uniform>
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<uniform>
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<name>rK</name>
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<type>float</type>
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<value><use>rayleigh</use></value>
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</uniform>
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<uniform>
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<name>density</name>
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<type>float</type>
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<value><use>density</use></value>
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</uniform>
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</pass>
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</technique>
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<!-- fall back without shaders -->
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<technique n="11">
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<pass>
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<lighting>false</lighting>
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<shade-model>smooth</shade-model>
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<cull-face>back</cull-face>
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</pass>
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</technique>
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</PropertyList>
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40
Shaders/skydome.frag
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40
Shaders/skydome.frag
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#version 120
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// Atmospheric scattering shader for flightgear
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// Written by Lauri Peltonen (Zan)
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// Implementation of O'Neil's algorithm
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varying vec3 rayleigh;
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varying vec3 mie;
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varying vec3 eye;
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float miePhase(in float cosTheta, in float g)
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{
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float g2 = g*g;
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float a = 1.5 * (1.0 - g2);
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float b = (2.0 + g2);
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float c = 1.0 + cosTheta*cosTheta;
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float d = pow(1.0 + g2 - 2.0 * g * cosTheta, 0.6667);
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return (a*c) / (b*d);
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}
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float rayleighPhase(in float cosTheta)
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{
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//return 1.5 * (1.0 + cosTheta*cosTheta);
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return 1.5 * (2.0 + 0.5*cosTheta*cosTheta);
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}
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void main()
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{
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float cosTheta = dot(normalize(eye), gl_LightSource[0].position.xyz);
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vec3 color = rayleigh * rayleighPhase(cosTheta);
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color += mie * miePhase(cosTheta, -0.8);
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gl_FragColor = vec4(color, 1.0);
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gl_FragDepth = 0.1;
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}
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172
Shaders/skydome.vert
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Shaders/skydome.vert
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#version 120
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// Atmospheric scattering shader for flightgear
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// Written by Lauri Peltonen (Zan)
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// Implementation of O'Neil's algorithm
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uniform mat4 osg_ViewMatrix;
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uniform mat4 osg_ViewMatrixInverse;
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varying vec3 rayleigh;
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varying vec3 mie;
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varying vec3 eye;
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// Dome parameters from FG and screen
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const float domeSize = 80000.0;
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const float realDomeSize = 100000.0;
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const float groundRadius = 0.984503332 * domeSize;
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const float altitudeScale = domeSize - groundRadius;
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// Dome parameters when calculating scattering
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// Assuming dome size is 5.0
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const float groundLevel = 0.984503332 * 5.0;
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const float heightScale = (5.0 - groundLevel);
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// Integration parameters
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const int nSamples = 7;
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const float fSamples = float(nSamples);
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// Scattering parameters
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uniform float rK = 0.0003; //0.00015;
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uniform float mK = 0.003; //0.0025;
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uniform float density = 0.5; //1.0
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vec3 rayleighK = rK * vec3(5.602, 7.222, 19.644);
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vec3 mieK = vec3(mK);
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vec3 sunIntensity = 10.0*vec3(120.0, 125.0, 130.0);
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// Find intersections of ray to skydome
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// ray must be normalized
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// cheight is camera height
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float intersection (in float cheight, in vec3 ray, in float rad2)
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{
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float B = 2.0 * cheight*ray.y;
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float C = cheight*cheight - rad2; // 25.0 is skydome radius * radius
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float fDet = max(0.0, B*B - 4.0 * C);
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return 0.5 * (-B - sqrt(fDet));
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}
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// Return the scale function at height = 0 for different thetas
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float outscatterscale(in float costheta)
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{
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float x = 1.0 - costheta;
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float a = 1.16941;
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float b = 0.618989;
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float c = 6.34484;
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float d = -31.4138;
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float e = 75.3249;
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float f = -80.1643;
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float g = 32.2878;
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return exp(a+x*(b+x*(c+x*(d+x*(e+x*(f+x*g))))));
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}
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// Return the amount of outscatter for different heights and thetas
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// assuming view ray hits the skydome
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// height is 0 at ground level and 1 at space
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// Assuming average density of atmosphere is at 1/4 height
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// and atmosphere height is 100 km
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float outscatter(in float costheta, in float height)
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{
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return density * outscatterscale(costheta) * exp(-4.0 * height);
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}
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void main()
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{
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// Make sure the dome is of a correct size
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vec4 realVertex = gl_Vertex; //vec4(normalize(gl_Vertex.xyz) * domeSize, 1.0);
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// Ground point (skydome center) in eye coordinates
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vec4 groundPoint = gl_ModelViewMatrix * vec4(0.0, 0.0, 0.0, 1.0);
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// Calculate altitude as the distance from skydome center to camera
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// Make it so that 0.0 is ground level and 1.0 is 100km (space) level
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float altitude = distance(groundPoint, vec4(0.0, 0.0, 0.0, 1.0));
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float scaledAltitude = altitude / realDomeSize;
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// Camera's position, z is up!
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float cameraRealAltitude = groundLevel + heightScale*scaledAltitude;
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vec3 camera = vec3(0.0, 0.0, cameraRealAltitude);
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vec3 sample = 5.0 * realVertex.xyz / domeSize; // Sample is the dome vertex
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vec3 relativePosition = camera - sample; // Relative position
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// Find intersection of skydome and view ray
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float space = intersection(cameraRealAltitude, -normalize(relativePosition), 25.0);
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if(space > 0.0) {
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// We are in space, calculate correct positiondelta!
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relativePosition -= space * normalize(relativePosition);
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}
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vec3 positionDelta = relativePosition / fSamples;
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float deltaLength = length(positionDelta); // Should multiply by something?
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vec3 lightDirection = gl_LightSource[0].position.xyz;
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// Cos theta of camera's position and sample point
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// Since camera is 0,0,z, dot porduct is just the z coordinate
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float cameraCosTheta;
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// If sample is above camera, reverse ray direction
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if(positionDelta.z < 0.0) cameraCosTheta = -positionDelta.z / deltaLength;
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else cameraCosTheta = positionDelta.z / deltaLength;
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// Total attenuation from camera to skydome
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float totalCameraScatter = outscatter(cameraCosTheta, scaledAltitude);
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// Do numerical integration of scsattering function from skydome to camera
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vec3 color = vec3(0.0);
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for(int i = 0; i < nSamples; i++)
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{
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// Altitude of the sample point 0...1
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float sampleAltitude = (length(sample) - groundLevel) / heightScale;
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// Cosine between the angle of sample's up vector and sun
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// Since lightDirection is in eye space, we must transform sample too
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vec3 sampleUp = gl_NormalMatrix * normalize(sample);
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float cosTheta = dot(sampleUp, lightDirection);
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// Scattering from sky to sample point
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float skyScatter = outscatter(cosTheta, sampleAltitude);
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// Calculate the attenuation from this point to camera
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// Again, reverse the direction if vertex is over the camera
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float cameraScatter;
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if(relativePosition.z < 0.0) { // Vertex is over the camera
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cameraCosTheta = -dot(normalize(positionDelta), normalize(sample));
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cameraScatter = totalCameraScatter - outscatter(cameraCosTheta, sampleAltitude);
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} else { // Vertex is below camera
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cameraCosTheta = dot(normalize(positionDelta), normalize(sample));
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cameraScatter = outscatter(cameraCosTheta, sampleAltitude) - totalCameraScatter;
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}
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// Total attenuation
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vec3 totalAttenuate = 4.0 * 3.14159 * (rayleighK + mieK) * (-skyScatter - cameraScatter);
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vec3 inScatter = exp(totalAttenuate - sampleAltitude*4.0);
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color += inScatter * deltaLength;
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sample += positionDelta;
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}
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color *= sunIntensity;
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rayleigh = rayleighK * color;
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mie = mieK * color;
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eye = gl_NormalMatrix * positionDelta;
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// We need to move the camera so that the dome appears to be centered around earth
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// to make the dome render correctly!
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float moveDown = -altitude; // Center dome on camera
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moveDown += groundRadius;
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moveDown += scaledAltitude * altitudeScale; // And move correctly according to altitude
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// Vertex transformed correctly so that at 100km we are at space border
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vec4 finalVertex = realVertex - vec4(0.0, 0.0, 1.0, 0.0) * moveDown;
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// Transform
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gl_Position = gl_ModelViewProjectionMatrix * finalVertex;
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}
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@ -8,13 +8,17 @@
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<group>
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<group>
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<layout>hbox</layout>
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<layout>hbox</layout>
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<empty><stretch>1</stretch></empty>
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<empty>
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<stretch>1</stretch>
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</empty>
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<text>
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<text>
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<label>Rendering options</label>
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<label>Rendering options</label>
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</text>
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</text>
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<empty><stretch>1</stretch></empty>
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<empty>
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<stretch>1</stretch>
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</empty>
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<button>
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<button>
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<pref-width>16</pref-width>
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<pref-width>16</pref-width>
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@ -544,6 +548,139 @@
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</text>
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</text>
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</group>
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</group>
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<group>
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<layout>hbox</layout>
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<text>
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<label>Experimental effects</label>
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<halign>left</halign>
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</text>
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<hrule>
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<stretch>true</stretch>
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</hrule>
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</group>
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<group>
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<layout>vbox</layout>
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<padding>10</padding>
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<checkbox>
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<halign>left</halign>
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<label>Skydome scattering</label>
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<name>skydome-scattering</name>
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<enable>
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<property>/sim/rendering/shader-effects</property>
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</enable>
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<property>/sim/rendering/scattering-shader</property>
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<binding>
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<command>dialog-apply</command>
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<object-name>skydome-scattering</object-name>
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</binding>
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</checkbox>
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</group>
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<group>
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<layout>hbox</layout>
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<halign>right</halign>
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<text>
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<label>Mie factor</label>
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<enable>
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<property>/sim/rendering/shader-effects</property>
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</enable>
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</text>
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<slider>
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<name>mie-factor</name>
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<enable>
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<property>/sim/rendering/shader-effects</property>
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</enable>
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<min>0.0</min>
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<max>0.01</max>
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<step>0.001</step>
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<property>/sim/rendering/mie</property>
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<binding>
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<command>dialog-apply</command>
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<object-name>mie-factor</object-name>
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</binding>
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</slider>
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<text>
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<enable>
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<property>/sim/rendering/shader-effects</property>
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</enable>
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<label>12345678</label>
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<format>%.3f</format>
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<live>true</live>
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<property>/sim/rendering/mie</property>
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</text>
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</group>
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<group>
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<layout>hbox</layout>
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<halign>right</halign>
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<text>
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<label>Rayleigh factor</label>
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<enable>
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<property>/sim/rendering/shader-effects</property>
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</enable>
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</text>
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<slider>
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<name>rayleigh-factor</name>
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<enable>
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<property>/sim/rendering/shader-effects</property>
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</enable>
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<min>0.0</min>
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<max>0.001</max>
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<step>0.0001</step>
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<property>/sim/rendering/rayleigh</property>
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<binding>
|
||||||
|
<command>dialog-apply</command>
|
||||||
|
<object-name>rayleigh-factor</object-name>
|
||||||
|
</binding>
|
||||||
|
</slider>
|
||||||
|
<text>
|
||||||
|
<enable>
|
||||||
|
<property>/sim/rendering/shader-effects</property>
|
||||||
|
</enable>
|
||||||
|
<label>12345678</label>
|
||||||
|
<format>%.4f</format>
|
||||||
|
<live>true</live>
|
||||||
|
<property>/sim/rendering/rayleigh</property>
|
||||||
|
</text>
|
||||||
|
</group>
|
||||||
|
|
||||||
|
<group>
|
||||||
|
<layout>hbox</layout>
|
||||||
|
<halign>right</halign>
|
||||||
|
<text>
|
||||||
|
<label>Density factor</label>
|
||||||
|
<enable>
|
||||||
|
<property>/sim/rendering/shader-effects</property>
|
||||||
|
</enable>
|
||||||
|
</text>
|
||||||
|
<slider>
|
||||||
|
<name>density-factor</name>
|
||||||
|
<enable>
|
||||||
|
<property>/sim/rendering/shader-effects</property>
|
||||||
|
</enable>
|
||||||
|
<min>0.0</min>
|
||||||
|
<max>1.0</max>
|
||||||
|
<step>0.1</step>
|
||||||
|
<property>/sim/rendering/dome-density</property>
|
||||||
|
<binding>
|
||||||
|
<command>dialog-apply</command>
|
||||||
|
<object-name>density-factor</object-name>
|
||||||
|
</binding>
|
||||||
|
</slider>
|
||||||
|
<text>
|
||||||
|
<enable>
|
||||||
|
<property>/sim/rendering/shader-effects</property>
|
||||||
|
</enable>
|
||||||
|
<label>12345678</label>
|
||||||
|
<format>%.1f</format>
|
||||||
|
<live>true</live>
|
||||||
|
<property>/sim/rendering/dome-density</property>
|
||||||
|
</text>
|
||||||
|
</group>
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
</group>
|
</group>
|
||||||
</group>
|
</group>
|
||||||
|
|
||||||
|
|
|
||||||
Loading…
Add table
Reference in a new issue