From c1a66dd653d229f35df095cbe80631d623dbee82 Mon Sep 17 00:00:00 2001
From: Luxdragon <kopse@e.email>
Date: Tue, 27 Feb 2024 19:01:28 +0100
Subject: [PATCH] Added the intervals struct

---
 main.go | 45 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 38 insertions(+), 7 deletions(-)

diff --git a/main.go b/main.go
index ac867c2..1d476a0 100644
--- a/main.go
+++ b/main.go
@@ -159,6 +159,37 @@ func (r *Ray) At(t float32) Vec3 {
 	}
 }
 
+// =============== INTERVAL =================
+
+type Interval struct {
+	min, max float32
+}
+
+func NewInterval(borders ...float32) *Interval {
+	if (len(borders) == 2) {
+		return &Interval{
+			min: borders[0],
+			max: borders[1],
+		}
+	} else {
+		return &Interval{
+			min: float32(math.Inf(1)),
+			max: float32(math.Inf(-1)),
+		}
+	}
+}
+
+func (i *Interval) Contains(x float32) bool {
+	return i.min <= x && x <= i.max
+}
+
+func (i *Interval) Surrounds(x float32) bool {
+	return i.min < x && x < i.max
+}
+
+var Empty *Interval = NewInterval()
+var Universe *Interval = NewInterval(float32(math.Inf(-1)), float32(math.Inf(1)))
+
 
 // =============== HIT ======================
 
@@ -187,7 +218,7 @@ type Sphere struct {
 	radius float32
 }
 
-func (s Sphere) Hit_sphere(r *Ray, ray_tmin float32, ray_tmax float32, rec *Hit_record) bool {
+func (s Sphere) Hit_sphere(r *Ray, ray_t *Interval, rec *Hit_record) bool {
 	oc := r.Origin().Sub(s.center)
 	a := r.Direction().Length_squared()
 	half_b := Dot(oc, r.Direction())
@@ -201,9 +232,9 @@ func (s Sphere) Hit_sphere(r *Ray, ray_tmin float32, ray_tmax float32, rec *Hit_
 
 	// find the nearest root that lies in the acceptable range
 	root := (-half_b - sqrtd) / a
-	if (root <= ray_tmin || ray_tmax<= root) {
+	if (!ray_t.Surrounds(root)) {
 		root = (sqrtd-half_b) / a
-		if (root <= ray_tmin || ray_tmax <= root) {
+		if (!ray_t.Surrounds(root)) {
 			return false
 		}
 	}
@@ -231,13 +262,13 @@ func (hl *Hittable) Clear() {
 	hl.spheres = []Sphere{}
 }
 
-func (hl Hittable) Hit(r *Ray, ray_tmin float32, ray_tmax float32, rec *Hit_record) bool {
+func (hl Hittable) Hit(r *Ray, ray_t Interval, rec *Hit_record) bool {
 	var temp_rec Hit_record
 	var hit_anything bool = false
-	var closest_so_far float32 = ray_tmax
+	var closest_so_far float32 = ray_t.max
 
 	for _, sphere := range hl.spheres {
-		if (sphere.Hit_sphere(r, ray_tmin, closest_so_far, &temp_rec)) {
+		if (sphere.Hit_sphere(r, NewInterval(ray_t.min, closest_so_far), &temp_rec)) {
 			hit_anything = true
 			closest_so_far = temp_rec.t
 			*rec = temp_rec
@@ -248,7 +279,7 @@ func (hl Hittable) Hit(r *Ray, ray_tmin float32, ray_tmax float32, rec *Hit_reco
 
 func Ray_color(r Ray, world *Hittable) Vec3 {
 	var rec Hit_record
-	if (world.Hit(&r, 0, float32(math.Inf(1)), &rec)) {
+	if (world.Hit(&r, *NewInterval(0, float32(math.Inf(1))), &rec)) {
 		return rec.normal.Add(NewColor(1,1,1)).Mult(0.5)
 	}
 	unit_direction := Unit_vector(r.Direction())