[CORE][ADD] Boundary Class

- Hit test (AABB method)
- API to update current boundary by new point

FinalProject/boundary.cpp

@@ -0,0 +1,43 @@
+#include <algorithm>
+
+#include "boundary.h"
+
+void Boundary::updateControlPoints(const glm::vec3 point) {
+    _bottomControlPoint.x = std::min(_bottomControlPoint.x, point.x);
+    _bottomControlPoint.y = std::min(_bottomControlPoint.y, point.y);
+    _bottomControlPoint.z = std::min(_bottomControlPoint.z, point.z);
+    _topControlPoint.x = std::max(_topControlPoint.x, point.x);
+    _topControlPoint.y = std::max(_topControlPoint.y, point.y);
+    _topControlPoint.z = std::max(_topControlPoint.z, point.z);
+}
+
+bool Boundary::hit(const Ray& ray) const {
+    // Test whether the ray intersects with the boundary box
+    // The boundary box is defined by the bottom back left control point and the top front right control point
+    // The ray is already transformed
+    
+    // Test x-axis
+    float tmin = (_bottomControlPoint.x - ray.origin().x) / ray.direction().x;
+    float tmax = (_topControlPoint.x - ray.origin().x) / ray.direction().x;
+    if (tmin > tmax) std::swap(tmin, tmax);
+    
+    // Test y-axis
+    float tymin = (_bottomControlPoint.y - ray.origin().y) / ray.direction().y;
+    float tymax = (_topControlPoint.y - ray.origin().y) / ray.direction().y;
+    if (tymin > tymax) std::swap(tymin, tymax);
+    
+    // Test z-axis
+    float tzmin = (_bottomControlPoint.z - ray.origin().z) / ray.direction().z;
+    float tzmax = (_topControlPoint.z - ray.origin().z) / ray.direction().z;
+    if (tzmin > tzmax) std::swap(tzmin, tzmax);
+
+    // Test t range of x-y and get the intersection of x-y
+    if ((tmin > tymax) || (tymin > tmax)) return false;
+    if (tymin > tmin) tmin = tymin;
+    if (tymax < tmax) tmax = tymax;
+    
+    // Test t range of x-y-z
+    if ((tmin > tzmax) || (tzmin > tmax)) return false;
+    
+    return true;
+}

FinalProject/boundary.h

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+#pragma once
+
+#include <GLM/glm.hpp>
+
+#include "ray.h"
+
+class Boundary {
+private:
+    glm::vec3 _bottomControlPoint;  // left back bottom
+    glm::vec3 _topControlPoint;     // right front top
+
+public:
+    Boundary() : _bottomControlPoint(glm::vec3(std::numeric_limits<float>::max())), _topControlPoint(glm::vec3(std::numeric_limits<float>::lowest())) {}
+    Boundary(glm::vec3 bottomControlPoint, glm::vec3 topControlPoint) : _bottomControlPoint(bottomControlPoint), _topControlPoint(topControlPoint) {}
+
+public:
+    void updateControlPoints(const glm::vec3 point);    // update the control points of the boundary box
+    
+    inline glm::vec3 bottomControlPoint() const { return _bottomControlPoint; }
+    inline glm::vec3 topControlPoint() const { return _topControlPoint; }
+    inline glm::vec3 bottomCenterPoint() const;
+
+    bool hit(const Ray& ray) const;
+};
+
+inline glm::vec3 Boundary::bottomCenterPoint() const {
+    return glm::vec3((_bottomControlPoint.x + _topControlPoint.x) / 2.0f, _bottomControlPoint.y, (_bottomControlPoint.z + _topControlPoint.z) / 2.0f);
+}