From 893176a0b18a2281abe09def716ccc3db5583c3f Mon Sep 17 00:00:00 2001
From: Julian T <julian@jtle.dk>
Date: Sun, 26 Jul 2020 12:56:27 +0200
Subject: Implemented object intersection and startet work on render gui

---
 src/object.cpp | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 src/object.cpp

(limited to 'src/object.cpp')

diff --git a/src/object.cpp b/src/object.cpp
new file mode 100644
index 0000000..e88ae13
--- /dev/null
+++ b/src/object.cpp
@@ -0,0 +1,89 @@
+#include "object.hpp"
+
+#include <math.h>
+#include "common.hpp"
+
+Sphere::Sphere(Vec3d center, double radius) {
+    m_center = center;
+    m_radius = radius;
+}
+
+Plane::Plane(Vec3d start, Vec3d norm) {
+    m_start = start;
+    m_norm = norm;
+
+    m_norm.normalize();
+}
+
+void Object::setMaterial(std::shared_ptr<Material> m) {
+    m_mat = m;
+}
+
+Vec3d Sphere::norm_at(const Vec3d &point, const Vec3d&) const {
+    auto res = point - m_center;
+    res.normalize();
+    return res;
+}
+
+// https://www.scratchapixel.com/lessons/3d-basic-rendering/minimal-ray-tracer-rendering-simple-shapes/ray-sphere-intersection
+double Sphere::intersect(const Ray &ray, bool skip_dist) const {
+    // Calculate O - C used multiple places
+    auto oc = ray.m_start - m_center;
+    // Calculate components of quadratic formula
+    // a = 1 when ray.direction is a unit vector
+    auto a = 1;
+    auto b = 2 * ray.m_direction.dot(oc);
+    auto c = oc.dot(oc) - m_radius * m_radius;
+
+    // Solve quadratic function
+    auto discr = b * b - 4 * a * c;
+    if (discr < 0) {
+        // No solution
+        return -1;
+    }
+    if (skip_dist) {
+        // Do not calculate distance
+        return 1;
+    }
+
+    auto q = (b > 0) ?
+        -0.5 * (b + sqrt(discr)):
+        -0.5 * (b - sqrt(discr));
+    auto t1 = q; // Assuming a = 1
+    auto t0 = c / q;
+
+    // Find correct result
+    if (t0 <= ZERO_APPROX) {
+        t0 = t1;
+    }
+
+    if (t0 <= ZERO_APPROX) {
+        return -1;
+    }
+
+    return t0;
+}
+
+Vec3d Plane::norm_at(const Vec3d&, const Vec3d &indir) const {
+    auto scale = m_norm.dot(indir);
+    return scale > 0 ? -m_norm : m_norm;
+}
+
+// https://www.scratchapixel.com/lessons/3d-basic-rendering/minimal-ray-tracer-rendering-simple-shapes/ray-plane-and-ray-disk-intersection
+// Requires that vectors are normalized
+// Skip dist is ignored as distance must be calculated
+double Plane::intersect(const Ray &ray, bool) const {
+    // If ray is parallel
+    auto nr = m_norm.dot(ray.m_direction);
+    if (abs(nr) < ZERO_APPROX) {
+        return -1;
+    }
+
+    // Calculate distance
+    auto dist = m_norm.dot(m_start - ray.m_start) / nr;
+    if (dist < 0) {
+        return -1;
+    }
+
+    return dist;
+}
-- 
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