Forums' Golden Nuggets

March 10, 2021 · View on GitHub

  • Efficient AABB/triangle intersection in C#
    Original Question

    Can anyone recommend an efficient port to CSharp of any of the public AABB/triangle intersection algorithms.

    I've been looking at Moller's approach, described abstractly here, and if I were to port it, I would probably start from this C++ version. This C++ library by Mike Vandelay seems like it could also be a great starting point.

    ...or... any other "wheel" that can take a triangle of Vector3's and tell me if it intersects with an AABB), relatively efficiently.

    There seem to be a variety of algorithms, but most seem to be written in c++, or just described abstractly in white papers and I need a c# specific implementation for our application. Efficiency is not key, but c# is. (though efficiency is obviously nice too of course ;p )

    Any C# options, before I wade through a "math" port ;) would be greatly appreciated! Thanks.

  • Get a specific bit from byte
    Original Question

    I have a byte, specifically one byte from a byte array which came in via UDP sent from another device. This byte stores the on/off state of 8 relays in the device.

    How do I get the value of a specific bit in said byte? Ideally an extension method would look the most elegant and returning a bool would make the most sense to me.

  • How to compare two shapes?
    Original Question

    Is there a way to compare two geometric shapes (or any two more generic data structures), without using the brute force when a tolerance is involved?

    The brute force (that is comparing each value of each object against each value of the other object) works but it's slow, and I can't use it.

    I tried sorting the data and comparing two sorted collections. It's fast, but it only works with zero tolerance. As soon as I add the tolerance I get lost. The problem is that two values can be identical when I compare and different when I sort.

  • Is generating a .PTX file a must?
    Original Question

    Is there a way to prevent the app from generating external .ptx file and integrate it into .exe itself, somehow?

    For example:

    I have my .exe and 3 dlls (glad, glfw3, sutil_7_sdk) from optix sdk samples and I’d like the .exe without the need to have the .ptx file with it. Is it possible?

  • Mod of negative number is melting my brain
    Original Question

    I'm trying to mod an integer to get an array position so that it will loop round. Doing i % arrayLength works fine for positive numbers but for negative numbers it all goes wrong.
    [...]
    so i need an implementation of

    int GetArrayIndex(int i, int arrayLength)

    such that:

    GetArrayIndex( 4, 3) == 1
    GetArrayIndex( 3, 3) == 0
    GetArrayIndex( 2, 3) == 2
    GetArrayIndex( 1, 3) == 1
    GetArrayIndex( 0, 3) == 0
    GetArrayIndex(-1, 3) == 2
    GetArrayIndex(-2, 3) == 1
    GetArrayIndex(-3, 3) == 0
    GetArrayIndex(-4, 3) == 2