Post by sbehnke on Jul 5, 2019 1:26:03 GMT
Scenario: The refracted color with a refracted ray
Given w ← default_world()
And A ← the first object in w
And A has:
| material.ambient | 1.0 |
| material.pattern | test_pattern() |
And B ← the second object in w
And B has:
| material.transparency | 1.0 |
| material.refractive_index | 1.5 |
And r ← ray(point(0, 0, 0.1), vector(0, 1, 0))
And xs ← intersections(-0.9899:A, -0.4899:B, 0.4899:B, 0.9899:A)
When comps ← prepare_computations(xs[2], r, xs)
And c ← refracted_color(w, comps, 5)
Then c = color(0, 0.99888, 0.04725)I'm having trouble getting this test to pass.
let w = World.defaultWorld()
let A = w.objects.first!
A.material.ambient = 1.0
A.material.pattern = TestPattern()
let B = w.objects.last!
B.material.transparency = 1.0
B.material.refractiveIndex = 1.5
let r = Ray(origin: .Point(x: 0, y: 0, z: 0.1), direction: .Vector(x: 0, y: 1, z: 0))
let xs = [Intersection(t: -0.9899, object: A),
Intersection(t: -0.4899, object: B),
Intersection(t: 0.4899, object: B),
Intersection(t: 0.9899, object: A)]
let comps = xs[2].prepareCopmutation(ray: r, xs: xs)
let c = w.refractedColor(computation: comps, remaining: 5)
XCTAssertEqual(c, Color(r: 0, g: 0.99888, b: 0.04725))My end result is:
XCTAssertEqual failed: ("Color(backing: [0.5, 0.5, 0.5])") is not equal to ("Color(backing: [0.0, 0.99888, 0.04725])")That seems really odd. I'm stepping through the recursion but I'm really sure where it is going sideways.
static func refractedColor(world: World, computation: Computation, remaining: Int = MaximumRecursionDepth) -> Color {
// Maximum recursion met, return black
if remaining < 1 || computation.object!.material.transparency == 0 {
return Color.black
}
// Check for total internal reflection with snells' law, return black
let nRatio = Double(computation.n1 / computation.n2)
let cosI = Tuple.dot(lhs: computation.eyeVector, rhs: computation.normalVector)
let sin2T = (nRatio * nRatio) * (1 - (cosI * cosI))
if sin2T > 1 {
return Color.black
}
let cosT = sqrt(1 - sin2T)
let direction = computation.normalVector * (nRatio * cosI - cosT) - computation.eyeVector * nRatio
let refractedRay = Ray(origin: computation.underPoint, direction: direction)
let color = colorAt(world: world, ray: refractedRay, remaining: remaining - 1) * computation.object!.material.transparency
return color
}Any help would be greatly appreciated! Loving the book!
