WPF 中的 3D 命中测试 [英] 3D Hit Testing in WPF

问题描述

我正在编写一个以 3D 形式显示地形的 WPF 应用程序.

I'm writing a WPF application that displays terrain in 3D.

当我执行命中测试时，返回了错误的 3D 点(不是我点击的点).

When I perform hit testing, the wrong 3D point is returned (not the point I clicked on).

我尝试突出显示被击中的三角形(通过创建一个新网格，从 RayMeshGeometry3DHitTestResult 对象获取坐标).我看到错误的三角形被击中(一个三角形被突出显示，但它不在光标下).

I tried highlighting the triangle that was hit (by creating a new mesh, taking the coordinates from the RayMeshGeometry3DHitTestResult object). I see that the wrong triangle gets hit (a triangle is highlighted, but it is not under the cursor).

我使用的是视角为 60 的透视相机，近平面和远平面分别为 3 和 35000.

I'm using a perspective camera with field of view of 60, and the near and far planes are of 3 and 35000 respectively.

知道为什么会发生这种情况以及我可以做些什么来解决它吗?

Any idea why it might happen and what I can do to solve it?

如果您需要更多数据，请告诉我.

Let me know if you need any more data.

这是我用来执行命中测试的代码:

This is the code I use to perform the hit testing:

private void m_viewport3d_MouseDown(object sender, MouseButtonEventArgs e)
{
    Point mousePos = e.GetPosition(m_viewport3d);
    PointHitTestParameters hitParams = new PointHitTestParameters(mousePos);
    HitTestResult result = VisualTreeHelper.HitTest(m_viewport3d, mousePos);
    RayMeshGeometry3DHitTestResult rayMeshResult = result as RayMeshGeometry3DHitTestResult;
    if (rayMeshResult != null)
    {
        MeshGeometry3D mesh = new MeshGeometry3D();
        mesh.Positions.Add(rayMeshResult.MeshHit.Positions[rayMeshResult.VertexIndex1]);
        mesh.Positions.Add(rayMeshResult.MeshHit.Positions[rayMeshResult.VertexIndex2]);
        mesh.Positions.Add(rayMeshResult.MeshHit.Positions[rayMeshResult.VertexIndex3]);
        mesh.TriangleIndices.Add(0);
        mesh.TriangleIndices.Add(1);
        mesh.TriangleIndices.Add(2);
        GeometryModel3D marker = new GeometryModel3D(mesh, new DiffuseMaterial(Brushes.Blue));
        //...add marker to the scene...
    }
}

推荐答案

发现这是一个 Normalize 问题.我不应该标准化相机的外观和向上矢量.在我使用的秤中，失真太大，命中测试无法正常工作.

Figures out it was a Normalize issue. I shouldn't have normalized the camera's look and up vectors. In the scales I'm using, the distortion is too big for the hit test to work correctly.

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