From bf18756a3d8b56f18198607f0eb191b4bb3faf28 Mon Sep 17 00:00:00 2001
From: Yoel <s73017@beuth-hochschule.de>
Date: Tue, 16 Mar 2021 14:38:52 +0100
Subject: [PATCH] Sphere intersection optimized
---
RayTracer/shape/Sphere.cpp | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/RayTracer/shape/Sphere.cpp b/RayTracer/shape/Sphere.cpp
index 65ab64f..87ca48d 100644
--- a/RayTracer/shape/Sphere.cpp
+++ b/RayTracer/shape/Sphere.cpp
@@ -19,21 +19,17 @@ std::optional<cam::Hit> Sphere::intersect(const cam::Ray& r) const {
float discrim = b * b - 4 * a * c;
if (discrim >= 0) {
- float t1 = (-b - sqrt(b * b - 4 * a * c)) / (2 * a);
+ float t1 = (-b - sqrt(discrim)) / (2 * a);
if (r.in_range(t1)) {
util::Vec3 t1HitPoint = r(t1);
- float theta = acos(t1HitPoint.y() / radius);
- float phi = M_PI + atan2(t1HitPoint.x(), t1HitPoint.z());
return std::optional<cam::Hit>({t1HitPoint, t1HitPoint,
texture_coordinates(t1HitPoint), t1,
material});
} else {
- float t2 = (-b + sqrt(b * b - 4 * a * c)) / (2 * a);
+ float t2 = (-b + sqrt(discrim)) / (2 * a);
if (r.in_range(t2)) {
util::Vec3 t2HitPoint = r(t2);
- float theta = acos(t2HitPoint.y() / radius);
- float phi = M_PI + atan2(t2HitPoint.x(), t2HitPoint.z());
return std::optional<cam::Hit>({t2HitPoint, t2HitPoint,
texture_coordinates(t2HitPoint),
t2, material});
@@ -74,10 +70,12 @@ util::Vec3 Sphere::calculateLightEmission(const util::SurfacePoint& p,
// the light in regard to the angle.
// Uniform pdf of shape is 1/area, converting to pdf over solid angle is
// pdf/(dot/length^2).
+ // This is wrong. We just need the normal pdf, per area, as we do not sample
+ // with regard to a direction.
auto emission = p.emission();
auto dot = std::max<float>(util::dot(p.normal(), d.normalize()), 0);
auto area = 4 * M_PI * std::pow(radius, 2);
- auto pdf = std::pow(d.length(), 2) / (dot * area);
+ auto pdf = 1 / area;
return emission / pdf;
}
} // namespace shapes
--
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