在3D空间中拉伸三角形集合

问题描述

你好，

谢谢您事先的帮助. :)

我一直在研究3D程序已经有一段时间了，它不使用DirectX或任何其他替代方法(作​​为一项技术挑战)，在.NET框架中使用GDI +.到目前为止，它完全可以与基本照明一起使用，请浏览导航等内容.

到目前为止，在该程序中，当您手动选择任何3D世界中的三角形时，它将以黄色点亮.现在，我想在单击按钮时将该面/三角形集合挤出给定的整数值. (类似于Blender或3DS Max之类的程序)

我曾尝试使用Google搜索，但结果却被冰淇淋挤出机遮盖了:D:p

我想我要问的是正确方向的指针，或有关其背后数学的一些帮助.我可能缺少一些非常简单的内容.


在程序中
三角形结构只是3个位置向量的集合. (使用法线和幅值等方法的全部方法)

Hello,

Thank you for any help in advance. :)

I have been working on a 3D program for a while now that doesn''t use DirectX or any other alternative (As a technical challenge), Uses GDI+ in .NET framework. So far its fully working with basic lighting, walk around navigation e.t.c.

In the program so far when you make a manual selection of triangles in any 3D world it will illuminate them yellow. I would now like to extrude that face/triangle collection a given integer amount on a button click. (Similar to programs like blender or 3DS Max)

I have tried googling but my results are just clouded with ice-cream extruding machines :D :p

I suppose what i''m asking is pointers in the right direction or some help with the math behind it. I''m probably missing something quite simple.


In the program
Triangle structure is a just a collection of 3 location vectors. (With a whole load of methods for normal and magnitude and such like)

推荐答案

//define a vector (will be used also for points)
struct Vector3
{
    public double X { get; set; }
    public double Y { get; set; }
    public double Z { get; set; }

    //default constructor
    public Vector3() {}
    //constructs a vector from 2 points
    public Vector3(Vector3 A, Vector3 B)
    {
        X = B.X - A.X;
        Y = B.Y - A.Y;
        Z = B.Z - A.Z;
    }

    //normalizes this vector
    public void Normalize()
    {
        float d = Math.Sqrt(X * X + Y * Y + Z * Z);
        if (d == 0)
            return;
        X /= d;
        Y /= d;
        Z /= d;
    }

    // returns the cross product between vectors u and v
    static public Vector3 CrossProduct(Vector3 u, Vector3 v)
    {
        Vector3 w = new Vector3();
        w.X = u.Y * v.Z - u.Z * v.Y;
        w.Y = u.Z * v.X - u.X * v.Z;
        w.Z = u.X * v.Y - u.Y * v.X;
        return w;
    }
}

//defines a face
struct Face
{
    public Vector3 A { get; set; }
    public Vector3 B { get; set; }
    public Vector3 C { get; set; }

    // returns a normalized normal vector
    // use this vector for your extrusion
    public Vector3 GetNormal()
    {
        Vector3 AB = new Vector3(A, B);
        Vector3 AC = new Vector3(A, C);
        Vector3 n = Vector3.CrossProduct(AB, AC);
        n.Normalize();
        return n;
    }
}

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