Background is now skysphere, sinus correction of distribution in cornstructor implemented

RayTracer/shape/Background.cpp → RayTracer/shape/SkySphere.cpp

-#include "Background.h"
+#include "SkySphere.h"
 #define _USE_MATH_DEFINES
 #include <limits>
 
@@ -6,9 +6,23 @@
 #include "math.h"
 
 namespace shapes {
-Background::Background(const std::shared_ptr<util::Sampler>& sampler)
+SkySphere::SkySphere(const std::shared_ptr<util::Sampler>& sampler)
     : Sphere(100, std::make_shared<material::BackgroundMaterial>(sampler)) {
 }
+SkySphere::SkySphere(const std::shared_ptr<util::Sampler>& sampler,
+                     util::Image& distribution)
+    : Sphere(100, std::make_shared<material::BackgroundMaterial>(sampler)) {
+	for (int x = 0; x < distribution.width; x++) {
+		for (int y = 0; y < distribution.height; y++) {
+			auto color = distribution[{x, y}];
+			auto sinn = sin(M_PI * ((float)y / distribution.height));
+			color = color * sinn;
+			distribution.setPixel(x, y, color);
+		}
+	}
+	material =
+	    std::make_shared<material::BackgroundMaterial>(sampler, distribution);
+}
 // Thit intersect method rightly flips the normal.But the normal is never used
 // for non scatter materials, so we do not flip the normal
 /*
@@ -21,7 +35,17 @@ std::optional<cam::Hit> Background::intersect(const cam::Ray& r) const {
     return hit;
 }*/
 
-util::AxisAlignedBoundingBox Background::bounds() const {
+float SkySphere::lightPdf(const util::SurfacePoint& p,
+                          const util::Vec3& dl_out) const {
+	auto uv = p.texel();
+	auto phi = uv.second * M_PI;
+	float pdf = material->emission_pdf(uv.first, uv.second).value_or(1);
+	pdf = pdf / (2 * M_PI * M_PI * sin(phi));
+
+	return pdf;
+}
+
+util::AxisAlignedBoundingBox SkySphere::bounds() const {
 	return util::AxisAlignedBoundingBox();
 }
 }  // namespace shapes
\ No newline at end of file

RayTracer/shape/Background.h → RayTracer/shape/SkySphere.h

 #pragma once
 
+#include "../sampling/Image.h"
 #include "../sampling/Sampler.h"
 #include "Shape.h"
 #include "Sphere.h"
 
 namespace shapes {
-class Background : public Sphere {
+class SkySphere : public Sphere {
    public:
-	Background(const std::shared_ptr<util::Sampler>& sampler);
+	SkySphere(const std::shared_ptr<util::Sampler>& sampler);
+	SkySphere(const std::shared_ptr<util::Sampler>& sampler,
+	           util::Image& distribution);
+	float lightPdf(const util::SurfacePoint& p,
+	               const util::Vec3& dl_out) const override;
 	// We should have to flip the normal, but it does not matter
 	// std::optional<cam::Hit> intersect(const cam::Ray& r) const override;
 	util::AxisAlignedBoundingBox bounds() const override;