doja

doja

The Ray Tracer Challenge: Cylinder test #7 (p185) - failed corner cases

Hi,

I’m stuck on the test for #7 “Intersecting the caps of a closed cylinder”.
Tests 3 & 5 are failing as the intersections count is equal to one (one the cap intersection is detected).

After staring at the code for some time, any help is appreciated!

override internal func shapeSpecificIntersection(transformedRay:Ray<T>) -> Array<Intersection<T>> {
    var result = Array<Intersection<T>>()
    
    let a = transformedRay.direction.x * transformedRay.direction.x + transformedRay.direction.z * transformedRay.direction.z
    let b = 2 * transformedRay.origin.x * transformedRay.direction.x +
            2 * transformedRay.origin.z * transformedRay.direction.z
    if (a.magnitude < Self.defaultEpsilon || b.magnitude < Self.defaultEpsilon) {
        return intersectCaps(ray: transformedRay)
    }

    let c = transformedRay.origin.x * transformedRay.origin.x + transformedRay.origin.z * transformedRay.origin.z - 1

    
    let disc = b * b - 4 * a * c
    
    if (disc < 0) {
        return intersectCaps(ray: transformedRay)
    }
    
    var t0 = (-b - sqrt(disc)) / (2 * a)
    var t1 = (-b + sqrt(disc)) / (2 * a)

    if t0 > t1 {
        let tmp = t1
        t1 = t0
        t0 = tmp
    }

    let y0 = transformedRay.origin.y + t0 * transformedRay.direction.y
    if minimum < y0 && y0 < maximum {
        result.append(Intersection<T>(shape: self, t: t0))
    }
    
    let y1 = transformedRay.origin.y + t1 * transformedRay.direction.y
    if minimum < y1 && y1 < maximum {
        result.append(Intersection<T>(shape: self, t: t1))
    }
    
    result.append(contentsOf: intersectCaps(ray: transformedRay))
    
    return result
}

func checkCap(ray: Ray<T>, t: T) -> Bool {
    let x = ray.origin.x + t * ray.direction.x
    let z = ray.origin.z + t * ray.direction.z
    
    return (x * x) + (z * z) <= 1
}

func intersectCaps(ray: Ray<T>) -> Array<Intersection<T>> {
    var result = Array<Intersection<T>>()
    
    if !closed {
        return result
    }
        
    var t = (minimum - ray.origin.y) / ray.direction.y
    if (checkCap(ray: ray, t: t)) {
        result.append(Intersection<T>(shape: self, t: t))
    }
        
    t = (maximum - ray.origin.y) / ray.direction.y
    if (checkCap(ray:ray, t: t)) {
        result.append(Intersection<T>(shape: self, t: t))
    }
    
    return result
}

Best regards & happy coding! doja

Where Next?

Popular Pragmatic Bookshelf topics Top

abtin
page 20: … protoc command… I had to additionally run the following go get commands in order to be able to compile protobuf code using go...
New
Alexandr
Hi everyone! There is an error on the page 71 in the book “Programming machine learning from coding to depp learning” P. Perrotta. You c...
New
raul
Page 28: It implements io.ReaderAt on the store type. Sorry if it’s a dumb question but was the io.ReaderAt supposed to be io.ReadAt? ...
New
HarryDeveloper
Hi @venkats, It has been mentioned in the description of ‘Supervisory Job’ title that 2 things as mentioned below result in the same eff...
New
AleksandrKudashkin
On the page xv there is an instruction to run bin/setup from the main folder. I downloaded the source code today (12/03/21) and can’t see...
New
patoncrispy
I’m new to Rust and am using this book to learn more as well as to feed my interest in game dev. I’ve just finished the flappy dragon exa...
New
fynn
This is as much a suggestion as a question, as a note for others. Locally the SGP30 wasn’t available, so I ordered a SGP40. On page 53, ...
New
dsmith42
Hey there, I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “&gt;...
New
AufHe
I’m a newbie to Rails 7 and have hit an issue with the bin/Dev script mentioned on pages 112-113. Iteration A1 - Seeing the list of prod...
New
dachristenson
@mfazio23 Android Studio will not accept anything I do when trying to use the Transformations class, as described on pp. 140-141. Googl...
New

Other popular topics Top

AstonJ
If it’s a mechanical keyboard, which switches do you have? Would you recommend it? Why? What will your next keyboard be? Pics always w...
New
AstonJ
What chair do you have while working… and why? Is there a ‘best’ type of chair or working position for developers?
New
AstonJ
We have a thread about the keyboards we have, but what about nice keyboards we come across that we want? If you have seen any that look n...
New
AstonJ
Do the test and post your score :nerd_face: :keyboard: If possible, please add info such as the keyboard you’re using, the layout (Qw...
New
PragmaticBookshelf
Tailwind CSS is an exciting new CSS framework that allows you to design your site by composing simple utility classes to create complex e...
New
AstonJ
If you are experiencing Rails console using 100% CPU on your dev machine, then updating your development and test gems might fix the issu...
New
PragmaticBookshelf
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
First poster: joeb
The File System Access API with Origin Private File System. WebKit supports new API that makes it possible for web apps to create, open,...
New
hilfordjames
There appears to have been an update that has changed the terminology for what has previously been known as the Taskbar Overflow - this h...
New
PragmaticBookshelf
Author Spotlight: Peter Ullrich @PJUllrich Data is at the core of every business, but it is useless if nobody can access and analyze ...
New

Sub Categories: