func TestBoundingBoxSplit(t *testing.T) {
box := &BoundingBox{
MinVolume: [3]float64{-3.18, -3.96, -1.77},
MaxVolume: [3]float64{4.58, 1.74, 4.56},
}
ray := &ray.Ray{
Start: *maths.NewVec3(4.49, -7.3, 5.53),
Direction: *maths.NewVec3(-0.60, 0.5, -0.62),
}
ray.Init()
if !box.Intersect(ray) {
t.Error("ray should intersect big box")
}
left, right := box.Split(2, 1.39)
assertEqualVectors(t, maths.NewVec3(-3.18, -3.96, -1.77), maths.NewVec3Array(left.MinVolume))
assertEqualVectors(t, maths.NewVec3(-3.18, -3.96, 1.39), maths.NewVec3Array(right.MinVolume))
assertEqualVectors(t, maths.NewVec3(4.58, 1.74, 1.39), maths.NewVec3Array(left.MaxVolume))
assertEqualVectors(t, maths.NewVec3(4.58, 1.74, 4.56), maths.NewVec3Array(right.MaxVolume))
if box.IntersectWall(2, 1.39, ray) {
t.Error("ray shouldn't intersect the wall")
}
if right.Intersect(ray) {
t.Error("ray shouldn't intersect right")
}
if !left.Intersect(ray) {
t.Error("ray should intersect left")
}
}
// IntersectTriangle checks if the bounding box intersects with a triangle
// 1) To have a vertex in the box
// 2) The edge of the triangle intersects with the box
// 3) The middle of the triangle to be inside the box, while the vertices aren't
func (b *BoundingBox) IntersectTriangle(A, B, C *maths.Vec3) bool {
if b.Inside(A) || b.Inside(B) || b.Inside(C) {
return true
}
// we construct the ray from A->B, A->C, etc and check whether it intersects with the box
triangle := [3]*maths.Vec3{A, B, C}
ray := &ray.Ray{}
for rayStart := 0; rayStart < 3; rayStart++ {
for rayEnd := rayStart + 1; rayEnd < 3; rayEnd++ {
ray.Start = *(triangle[rayStart])
ray.Direction = *maths.MinusVectors(triangle[rayEnd], triangle[rayStart])
ray.Init()
// Check if there's intersection between AB and the box (example)
if b.Intersect(ray) {
// we check whether there's intersection between BA and the Box too
// to be sure the edge isn't outside the box
// _____
// | | <----AB there is intersection, but BA----->
// |____|
ray.Start = *triangle[rayEnd]
ray.Direction = *maths.MinusVectors(triangle[rayStart], triangle[rayEnd])
ray.Init()
if b.Intersect(ray) {
return true
}
}
}
}
// we have to check if the inside of the triangle intersects with the box
AB := maths.MinusVectors(B, A)
AC := maths.MinusVectors(C, A)
ABxAC := maths.CrossProduct(AB, AC)
distance := maths.DotProduct(A, ABxAC)
rayEnd := &maths.Vec3{}
for edgeMask := 0; edgeMask < 7; edgeMask++ {
for axis := uint(0); axis < 3; axis++ {
if edgeMask&(1<<axis) != 0 {
continue
}
if edgeMask&1 != 0 {
ray.Start.X = b.MaxVolume[0]
} else {
ray.Start.X = b.MinVolume[0]
}
if edgeMask&2 != 0 {
ray.Start.Y = b.MaxVolume[1]
} else {
ray.Start.Y = b.MinVolume[1]
}
if edgeMask&4 != 0 {
ray.Start.Z = b.MaxVolume[2]
} else {
ray.Start.Z = b.MinVolume[2]
}
*rayEnd = ray.Start
rayEnd.SetDimension(int(axis), b.MaxVolume[axis])
if (maths.DotProduct(&ray.Start, ABxAC)-distance)*(maths.DotProduct(rayEnd, ABxAC)-distance) <= 0 {
ray.Direction = *maths.MinusVectors(rayEnd, &ray.Start)
ray.Init()
intersected, distance := IntersectTriangle(ray, A, B, C)
if intersected && distance < 1.0000001 {
return true
}
}
}
}
return false
}
