Michaël Lemaire
6cd571f92f
git-svn-id: https://subversion.assembla.com/svn/thunderk/paysages@424 b1fd45b6-86a6-48da-8261-f70d1f35bdcc
83 lines
3.3 KiB
C
83 lines
3.3 KiB
C
#include "skyrayleigh.h"
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#include <math.h>
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#if 0
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static Vector3 _betaR = {5.5e-6, 13.0e-6, 22.4e-6}; /* Rayleigh scattering coefficients at sea level */
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static Vector3 _betaM = {21e-6, 0.0, 0.0}; /* Mie scattering coefficients at sea level */
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static double _Hr = 7994; /* Rayleigh scale height */
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static double _Hm = 1200; /* Mie scale height */
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static double _radiusEarth = 6360e3; /* Earth radius */
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static double _radiusAtmosphere = 6420e3; /* Atmosphere radius */
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static double _sunIntensity = 20.0; /* Sun intensity */
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static double _g = 0.76; /* Mean cosine */
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#endif
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/*typedef struct
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{
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double tmin;
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double tmax;
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} Ray;
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static Vector3 _computeIncidentLight(Ray r)
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{
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double t0, t1;
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int numSamples = 16;
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int numSamplesLight = 8;
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int i, j;
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if (!intersect<T>(r, radiusAtmosphere, t0, t1) || t1 < 0) return Vec3<T>(0);
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if (t0 > r.tmin && t0 > 0) r.tmin = t0;
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if (t1 < r.tmax) r.tmax = t1;
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double segmentLength = (r.tmax - r.tmin) / (double)numSamples;
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double tCurrent = r.tmin;
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Vector3 sumR = VECTOR_ZERO;
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Vector3 sumM = VECTOR_ZERO;
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double opticalDepthR = 0.0;
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double opticalDepthM = 0.0;
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double mu = r.direction.dot(sunDirection);
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double phaseR = 3.0 / (16.0 * M_PI) * (1.0 + mu * mu);
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double phaseM = 3.0 / (8.0 * M_PI) * ((1.0 - _g * _g) * (1 + mu * mu)) / ((2 + _g * _g) * pow(1 + _g * _g - 2 * _g * mu, 1.5));
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for (i = 0; i < numSamples; ++i)
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{
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Vector3 samplePosition = r(tCurrent + T(0.5) * segmentLength);
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double height = samplePosition.magnitude() - radiusEarth;
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double hr = exp(-height / _Hr) * segmentLength;
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double hm = exp(-height / _Hm) * segmentLength;
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opticalDepthR += hr;
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opticalDepthM += hm;
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Ray lightRay(samplePosition, sunDirection);
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intersect(lightRay, radiusAtmosphere, lightRay.tmin, lightRay.tmax);
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double segmentLengthLight = lightRay.tmax / numSamplesLight;
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double tCurrentLight = 0.0;
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double opticalDepthLightR = 0.0;
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double opticalDepthLightM = 0.0;
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for (j = 0; j < numSamplesLight; ++j) {
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Vector3 samplePositionLight = lightRay(tCurrentLight + T(0.5) * segmentLengthLight);
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T heightLight = samplePositionLight.magnitude() - radiusEarth;
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if (heightLight < 0) break;
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opticalDepthLightR += exp(-heightLight / Hr) * segmentLengthLight;
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opticalDepthLightM += exp(-heightLight / Hm) * segmentLengthLight;
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tCurrentLight += segmentLengthLight;
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}
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if (j == numSamplesLight) {
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Vec3<T> tau = betaR * (opticalDepthR + opticalDepthLightR) + betaM * 1.1 * (opticalDepthM + opticalDepthLightM);
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Vec3<T> attenuation(exp(-tau.x), exp(-tau.y), exp(-tau.z));
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sumR += hr * attenuation;
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sumM += hm * attenuation;
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}
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tCurrent += segmentLength;
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}
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return 20 * (sumR * phaseR * _betaR + sumM * phaseM * _betaM);
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}*/
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Color skyRayleighGetColor(Vector3 viewer, Vector3 direction, Vector3 sun_direction)
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{
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return COLOR_BLACK;
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}
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Color skyRayleighApplyToObject(Vector3 viewer, Vector3 object_location, Vector3 sun_direction, Color object_color)
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{
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return COLOR_BLACK;
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}
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