List of hittables added

main.go

@@ -63,6 +63,10 @@ func (v Vec3) Length() float32 {
 	return float32(math.Sqrt(float64(v.E[0]*v.E[0] + v.E[1]*v.E[1] + v.E[2]*v.E[2])))
 }
 
+func (v Vec3) Length_squared() float32 {
+	return v.E[0]*v.E[0] + v.E[1]*v.E[1] + v.E[2]*v.E[2]
+}
+
 // Vector utility functions
 
 func (v Vec3) String() string {
@@ -107,6 +111,12 @@ func Unit_vector(v Vec3) Vec3 {
     return new_v
 }
 
+const pi float32 = 3.1415926535897932385
+
+func Degrees_to_radians(degrees float32) float32 {
+	return (degrees * pi) / 180.0
+}
+
 // ============== COLOUR CLASS ==============
 
 func Write_color(v Vec3) {
@@ -149,32 +159,103 @@ func (r *Ray) At(t float32) Vec3 {
 	}
 }
 
-func Ray_color(r *Ray) Vec3 {
-	var t float32 = hit_sphere(NewPoint3(0,0,-1), 0.5, r)
-	if (t > 0.0) {
-		N := Unit_vector(r.At(t).Sub(NewVec3(0,0,-1)))
-		return NewColor(N.X()+1, N.Y()+1, N.Z()+1).Mult(0.5)
-	}
-	
-	unit_direction := Unit_vector(r.Direction())
-	a := (unit_direction.Y() + 1.0)*0.5
 
-	return NewColor(1.0,1.0,1.0).Mult(float32(1.0-a)).Add(NewColor(0.5,0.7,1.0).Mult(a))
+// =============== HIT ======================
+
+type Hit_record struct {
+	p Vec3
+	normal Vec3
+	t float32
+	front_face bool
+}
+
+func (rec *Hit_record) Set_face_normal(r *Ray, outward_normal Vec3) {
+	if (Dot(r.Direction(), outward_normal) < 0) {
+		rec.front_face = true
+	}
+	if (rec.front_face) {
+		rec.normal = outward_normal
+	} else {
+		rec.normal = outward_normal.Neg()
+	}
 }
 
 // =============== SPHERE ===================
 
-func hit_sphere(center Vec3, radius float32, r *Ray) float32 {
-	oc := r.Origin().Sub(center)
-	a := Dot(r.Direction(), r.Direction())
-	b := Dot(oc, r.Direction()) * 2.0
-	c := Dot(oc, oc) - radius*radius
-	discriminant := b*b - 4*a*c
+type Sphere struct {
+	center Vec3
+	radius float32
+}
+
+func (s Sphere) Hit_sphere(r *Ray, ray_tmin float32, ray_tmax float32, rec *Hit_record) bool {
+	oc := r.Origin().Sub(s.center)
+	a := r.Direction().Length_squared()
+	half_b := Dot(oc, r.Direction())
+	c := oc.Length_squared() - s.radius*s.radius
+
+	discriminant := half_b*half_b - a*c
 	if (discriminant < 0) {
-		return -1.0
-	} else {
-		return (-b-float32(math.Sqrt(float64(discriminant)))) / (2.0*a)
+		return false
 	}
+	sqrtd := float32(math.Sqrt(float64(discriminant)))
+
+	// find the nearest root that lies in the acceptable range
+	root := (-half_b - sqrtd) / a
+	if (root <= ray_tmin || ray_tmax<= root) {
+		root = (sqrtd-half_b) / a
+		if (root <= ray_tmin || ray_tmax <= root) {
+			return false
+		}
+	}
+	rec.t = root
+	rec.p = r.At(rec.t)
+	outward_normal := rec.p.Sub(s.center).Div(s.radius)
+	rec.Set_face_normal(r, outward_normal)
+	return true
+}
+
+// =============== HITTABLE ==================
+type Hittable struct {
+	spheres []Sphere
+}
+
+func NewHittable() *Hittable {
+	return &Hittable{}
+}
+
+func (hl *Hittable) Add(s Sphere) {
+	hl.spheres = append(hl.spheres, s)
+}
+
+func (hl *Hittable) Clear() {
+	hl.spheres = []Sphere{}
+}
+
+func (hl Hittable) Hit(r *Ray, ray_tmin float32, ray_tmax float32, rec *Hit_record) bool {
+	var temp_rec Hit_record
+	var hit_anything bool = false
+	var closest_so_far float32 = ray_tmax
+
+	for _, sphere := range hl.spheres {
+		if (sphere.Hit_sphere(r, ray_tmin, closest_so_far, &temp_rec)) {
+			hit_anything = true
+			closest_so_far = temp_rec.t
+			*rec = temp_rec
+		}
+	}
+	return hit_anything
+}
+
+func Ray_color(r Ray, world *Hittable) Vec3 {
+	var rec Hit_record
+	if (world.Hit(&r, 0, float32(math.Inf(1)), &rec)) {
+		return rec.normal.Add(NewColor(1,1,1)).Mult(0.5)
+	}
+	unit_direction := Unit_vector(r.Direction())
+	a := (unit_direction.Y() + 1.0)*0.5
+
+	return NewColor(1.0,1.0,1.0).Mult(float32(1.0-a)).Add(NewColor(0.5,0.7,1.0).Mult(a))
+
 }
 
 // =============== MAIN =====================
@@ -189,6 +270,19 @@ func main() {
 	 if image_height < 1 {
 		image_height = 1
 	 }
+
+	 // World
+
+	 world := NewHittable()
+	 world.Add(Sphere{
+		 center: NewVec3(0, 0, -1),
+		 radius: 0.5,
+	 })
+	 world.Add(Sphere{
+		 center: NewVec3(0, -100.5, -1),
+		 radius: 100,
+	 })
+	 
 	 // Camera
 	 var focal_length float32 = 1.0
 	 var viewport_height float32 = 2.0
@@ -212,22 +306,11 @@ func main() {
      for j := 0; j < image_height; j++ {
           fmt.Fprintf(os.Stderr, "\rScanlines remaining: %d ", image_height-j)
           for i := 0; i < image_width; i++ {
-               // r := float32(i) / float32(image_width - 1)
-               // g := float32(j) / float32(image_height-1)
-               // b := 0
-
-               // ir := int(r * 256)
-               // ig := int(g * 256)
-               // ib := int(b * 256)
-               // fmt.Println(ir, " ", ig, " ", ib)
-
-               //pixel_colour := NewVec3(float32(i) / float32(image_width - 1), float32(j) / float32(image_height-1), 0)
-               //Write_color(pixel_colour)
 			   pixel_center := pixel00_loc.Add(pixel_delta_u.Mult(float32(i))).Add(pixel_delta_v.Mult(float32(j)))
 			   ray_direction := pixel_center.Sub(camera_center)
 			   r := NewRay(camera_center, ray_direction)
 
-			   pixel_color := Ray_color(r)
+			   pixel_color := Ray_color(*r, world)
 			   Write_color(pixel_color)
           }
      }