I am a cloud god now
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133f8444d2
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dd92e85861
3 changed files with 114 additions and 74 deletions
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@ -32,7 +32,8 @@ int main()
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// scene.setBackgroundColor(Color(1, 0.79f, 0.62f) * 0.8f);
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// Add lights
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auto mainLight = std::make_shared<SunLight>(Vector3d(-1.0f, -0.5f, -1.0f), 2.0f, Color(1,1,1));//Color(1, 0.79f, 0.62f));
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// Alternate direction Vector3d(1.0f, -0.5f, 1.0f)
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auto mainLight = std::make_shared<SunLight>(Vector3d(0, -1.0f, 0), 1.0f, Color(1,1,1));//Color(1, 0.79f, 0.62f));
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scene.add(mainLight);
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// scene.add(std::make_shared<AmbientLight>(0.3f));
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// auto light = std::make_shared<PointLight>(Vector3d(25.0f, 10.0f, 25.0f), 100.0f);
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@ -56,9 +57,8 @@ int main()
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// Add box for volume shader
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auto cloudSettings = CloudSettings();
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cloudSettings.scale = 15.0f;
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auto cloudShader = std::make_shared<CloudShader>(cloudSettings);
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scene.add(std::make_shared<Box>(Vector3d(20.0f, 10.0f, 20.0f), Vector3d(50.0f, 10.0f, 50.0f), cloudShader));
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scene.add(std::make_shared<Box>(Vector3d(20.0f, 15.0f, 20.0f), Vector3d(70.0f, 10.0f, 70.0f), cloudShader));
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// build the tree
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scene.buildTree();
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@ -73,7 +73,7 @@ int main()
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// Render the scene
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SuperRenderer sr;
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sr.setSuperSamplingFactor(1);
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sr.renderImage(scene, camera, 1024, 1024).save("result.png");
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sr.renderImage(scene, camera, 256, 256).save("result.png");
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return 0;
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}
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@ -1,3 +1,5 @@
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#include <cmath>
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#include <iostream>
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#include "cloudshader.h"
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#include "common/noise/cloudnoise.h"
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@ -32,34 +34,32 @@ Color CloudShader::shade(const Scene &scene, const Ray &ray) const
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if (cloudLength == 0.0f) return background; // No cloud or at edge
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// Calculate step length
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int noiseSamples = settings.densitySamples;
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float stepLength = cloudLength / (float) noiseSamples;
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float stepLength = settings.densitySteps;
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int noiseSamples = std::floor(cloudLength / stepLength);
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// Step through cloud
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float accumulatedDensity = 0.0f;
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float transmittance = 1.0f;
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Color cloudColor = Color(0, 0, 0);
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for (int i = 0; i < noiseSamples; ++i)
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{
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// Get sample point
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Vector3d lengthDirection = i * stepLength * ray.direction;
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Vector3d lengthDirection = (float) i * stepLength * ray.direction;
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Vector3d samplePoint = hitPoint + lengthDirection;
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// Get data at point
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float sampleDensity = getCloudDensity(samplePoint) * stepLength;
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float sampleDensity = getCloudDensity(samplePoint, ray.primitive) * stepLength;
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if (sampleDensity > 0)
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if (sampleDensity <= 0)
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{
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cloudColor += lightMarch(scene, samplePoint, lengthDirection, ray.primitive) * sampleDensity;
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continue;
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}
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accumulatedDensity += sampleDensity;
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cloudColor += lightMarch(scene, samplePoint, lengthDirection, ray.primitive) * sampleDensity * transmittance;
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transmittance *= calcBeer(sampleDensity * settings.lightAbsorptionThroughCloud);
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if (transmittance < TRANSMITTANCE_BREAK) break;
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}
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if (accumulatedDensity > 1)
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cloudColor /= accumulatedDensity;
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float transmittance = exp(-accumulatedDensity * settings.lightAbsorptionThroughCloud);
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return background * transmittance + cloudColor;
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}
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@ -74,17 +74,53 @@ CloudShader::CloudShader(const CloudSettings &settings) : settings(settings),
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cloudNoise.invert = true;
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}
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float CloudShader::getCloudDensity(Vector3d point) const
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float CloudShader::getCloudDensity(Vector3d point, Primitive const *primitive) const
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{
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point /= settings.scale;
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//! Requires the unscaled point
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float edgeDensity = getEdgeDensity(point, primitive);
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point /= settings.scale;
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float density = cloudNoise.getNoise(point);
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// Threshold
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// TODO: Smooth out!
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density = std::max(0.0f, density + settings.densityOffset) * settings.densityIntensity;
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return density;
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return density * edgeDensity;
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}
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float CloudShader::getEdgeDensity(const Vector3d &point, const Primitive *primitive) const
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{
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if (primitive == nullptr)
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{
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return 1;
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}
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Vector3d size = Vector3d(0, 0, 0);
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size.x = primitive->maximumBounds(0) - primitive->minimumBounds(0);
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size.y = primitive->maximumBounds(1) - primitive->minimumBounds(1);
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size.z = primitive->maximumBounds(2) - primitive->minimumBounds(2);
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Vector3d center = Vector3d(0, 0, 0);
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center.x = primitive->maximumBounds(0) + primitive->minimumBounds(0);
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center.y = primitive->maximumBounds(1) + primitive->minimumBounds(1);
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center.z = primitive->maximumBounds(2) + primitive->minimumBounds(2);
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center /= 2;
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Vector3d distance = point - center;
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distance.x = std::abs(distance.x);
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distance.y = std::abs(distance.y);
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distance.z = std::abs(distance.z);
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Vector3d distanceFromEdge = size / 2 - distance;
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distanceFromEdge.x = std::max(0.0f, distanceFromEdge.x);
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distanceFromEdge.y = std::max(0.0f, distanceFromEdge.y);
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distanceFromEdge.z = std::max(0.0f, distanceFromEdge.z);
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float fallOff = std::min(distanceFromEdge.x, std::min(distanceFromEdge.y, distanceFromEdge.z)) /
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settings.edgeFadeOffDistance;
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return std::min(1.0f, fallOff);
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}
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Color CloudShader::lightMarch(const Scene &scene, Vector3d currentInCloudPosition, Vector3d lengthDistance,
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@ -107,43 +143,33 @@ Color CloudShader::lightMarch(const Scene &scene, Vector3d currentInCloudPositio
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continue;
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}
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// Light ray
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// Light ray from object to light
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Ray lightRay;
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lightRay.origin = currentInCloudPosition;
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lightRay.direction = illumination.direction;
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lightRay.direction = -illumination.direction;
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lightRay.primitive = cloudObject;
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lightRay.length = 0; // Starting in cloud itself
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float density = this->rayDensity(lightRay, illumination.distance);
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density *= settings.lightAbsorptionTowardsLight;
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// Proper light calculation
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float transmittance = getDensityTransmittance(density);
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float scatter = scatterFactor(normalized(lengthDistance), illumination.direction);
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float transmittance = calcBeer(density * settings.lightAbsorptionTowardsLight);
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float factor = transmittance;
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if (density > 0)
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{
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factor = settings.darknessThreshold +
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(1.0f - settings.darknessThreshold) * factor * scatter;
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transmittance *= phase(normalized(lengthDistance), lightRay.direction);
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cloudColor += transmittance * illumination.color;
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}
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cloudColor += factor * illumination.color;
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}
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return cloudColor;
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}
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float CloudShader::getDensityTransmittance(float density) const
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{
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return exp(-density) * (1 - exp(-density * 2)) / 0.4f;
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float darknessFactor = settings.darknessThreshold +
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(1.0f - settings.darknessThreshold);
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return cloudColor * darknessFactor;
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}
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Color CloudShader::transparency(const Scene &scene, const Ray &ray, float maxLength) const
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{
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float density = rayDensity(ray, maxLength);
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float transmittance = exp(-density * settings.shadowLightAbsorption);
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float transmittance = calcBeer(density * settings.shadowLightAbsorption);
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transmittance = 1 - (1 - transmittance) * settings.shadowIntensity;
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return Color(1, 1, 1) * transmittance;
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@ -151,36 +177,38 @@ Color CloudShader::transparency(const Scene &scene, const Ray &ray, float maxLen
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float CloudShader::rayDensity(const Ray &ray, float maxLength) const
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{
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Vector3d startPoint = ray.origin + ray.direction * (ray.length + 0.0001f);
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Vector3d startPoint = ray.origin + ray.direction * (ray.length + REFR_EPS);
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// Determine length of cloud
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Ray cloudRay = ray;
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Ray cloudRay;
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cloudRay.origin = startPoint;
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cloudRay.length = INFINITY;
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cloudRay.direction = ray.direction;
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cloudRay.primitive = nullptr;
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// Get out of cloud primitive first
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if (ray.primitive != nullptr && !ray.primitive->intersect(cloudRay) || cloudRay.length == INFINITY ||
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cloudRay.length <= 0)
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{
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// Something went wrong => No density
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return 0;
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// Assume ray started in cloud
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cloudRay.length = ray.length;
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cloudRay.primitive = ray.primitive;
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}
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float cloudLength = std::min(cloudRay.length, maxLength - ray.length);
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// Calculate step length
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int noiseSamples = settings.lightSamples;
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float stepLength = cloudLength / (float) noiseSamples;
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float stepLength = settings.densitySteps;
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int noiseSamples = std::floor(cloudLength / stepLength);
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// Step through cloud
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float density = 0.0f;
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for (int i = 0; i < noiseSamples; ++i)
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{
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// Get sample point
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Vector3d samplePoint = startPoint + i * stepLength * ray.direction;
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Vector3d samplePoint = startPoint + (float) i * stepLength * ray.direction;
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// Get data at point
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density += getCloudDensity(samplePoint) * stepLength;
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density += getCloudDensity(samplePoint, ray.primitive) * stepLength;
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}
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// If there is length left, check if it is in the cloud recursively
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@ -201,26 +229,31 @@ float CloudShader::rayDensity(const Ray &ray, float maxLength) const
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return density;
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}
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float CloudShader::scatterFactor(Vector3d visualRay, Vector3d illuminationRay) const
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float CloudShader::phase(Vector3d visualRay, Vector3d illuminationRay) const
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{
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// The asymmetry parameter
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float g = settings.scatterWeight;
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// The angle between the visual and illumination rays
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float cosTheta = dotProduct(visualRay, illuminationRay);
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// The Dual-Lob Henyey-Greenstein function
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float blend = .5;
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float scatter = HenyeyGreenstein(cosTheta, g) * (1 - blend) + HenyeyGreenstein(cosTheta, -g) * blend;
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float phaseBlend = calcDualHenyeyGreenstein(cosTheta, settings.phaseA) * (1 - blend) +
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calcDualHenyeyGreenstein(cosTheta, -settings.phaseB) * blend;
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// Clamp the result to the range [0, 1]
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scatter = std::max(std::min(scatter, 1.0f), 0.0f);
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phaseBlend = std::max(std::min(phaseBlend, 1.0f), 0.0f);
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return scatter;
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return settings.phaseOffset + phaseBlend * settings.phaseIntensity;
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}
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float CloudShader::HenyeyGreenstein(float cosTheta, float g) const
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float CloudShader::calcBeer(float d)
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{
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float beer = std::exp(-d);
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return beer;
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}
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float CloudShader::calcDualHenyeyGreenstein(float cosTheta, float g)
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{
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float g2 = g * g;
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return (1 - g2) / (4 * 3.1415f * pow(1 + g2 - 2 * g * (cosTheta), 1.5f));
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return (1 - g2) / (4 * 3.1415f * std::pow(1 + g2 - 2 * g * (cosTheta), 1.5f));
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}
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@ -7,22 +7,25 @@
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#include "primitive/primitive.h"
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#include "common/noise/worleynoise.h"
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int const NOISE_SIZE = 128;
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float const TRANSMITTANCE_BREAK = 0.005f; // If transmittance goes below this limit, the cloud is considered opaque
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int const NOISE_SIZE = 64;
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float const TRANSMITTANCE_BREAK = 0.0001f; // If transmittance goes below this limit, the cloud is considered opaque
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struct CloudSettings
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{
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int densitySamples = 100;
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int lightSamples = 100;
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float scale = 10;
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float densityOffset = -0.57f;
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float densityIntensity = 7.0f; // 7.0f
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float darknessThreshold = 0.1f; // 0.07f
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float shadowIntensity = 0.6f;
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float shadowLightAbsorption = 1;
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float lightAbsorptionTowardsLight = 1.0f;
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float lightAbsorptionThroughCloud = 0.5f;
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float scatterWeight = 0.5f;
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float densitySteps = .2f; // .2f
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float scale = 30; // 30
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float densityOffset = -.55f; // -.55f
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float densityIntensity = 5.0f; // 5.0f
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float darknessThreshold = .1f; // .1f
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float shadowIntensity = .6f; // .6f
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float shadowLightAbsorption = 1; // 1
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float lightAbsorptionTowardsLight = 0.3f; // .3f
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float lightAbsorptionThroughCloud = .8f; // .8f // How dark should the background be where the cloud is? Higher values mean darker background
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float phaseA = .5f; // .5f
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float phaseB = .3f; // .3f
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float phaseOffset = .8f; // .8f
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float phaseIntensity = 1.0f; // 1.0f
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float edgeFadeOffDistance = .5f; // .5f
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};
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class CloudShader : public Shader
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@ -32,6 +35,7 @@ public:
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// Shader functions
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Color shade(Scene const &scene, Ray const &ray) const;
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Color transparency(const Scene &scene, const Ray &ray, float maxLength) const override;
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private:
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@ -42,17 +46,20 @@ private:
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Noise cloudNoise;
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float getCloudDensity(Vector3d point) const;
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float getCloudDensity(Vector3d point, const Primitive *primitive = nullptr) const;
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Color lightMarch(const Scene &scene, Vector3d currentInCloudPosition, Vector3d lengthDistance, const Primitive *cloudObject) const;
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Color lightMarch(const Scene &scene, Vector3d currentInCloudPosition, Vector3d lengthDistance,
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const Primitive *cloudObject) const;
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float rayDensity(const Ray &ray, float maxLength) const;
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float scatterFactor(Vector3d visualRay, Vector3d illuminationRay) const;
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float phase(Vector3d visualRay, Vector3d illuminationRay) const;
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float HenyeyGreenstein(float cosTheta, float g) const;
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static float calcDualHenyeyGreenstein(float cosTheta, float g) ;
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float getDensityTransmittance(float density) const;
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static float calcBeer(float d) ;
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float getEdgeDensity(const Vector3d &point, const Primitive *primitive) const;
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};
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