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WPF应用程序，以3D形式显示地形。

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

当我执行点击测试时，会返回错误的3D点（不是我单击的点） ）。

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（通过创建新网格，并从 RayMeshGeometry3DHitTestResult 对象）。我看到错误的三角形被击中（三角形突出显示，但不在光标下方）。

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).

我正在使用视角为60，而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.

任何人知道为什么会发生这种情况以及我可以采取什么措施？

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

让我知道是否需要更多数据。

Let me know if you need any more data.

编辑：这是我用来执行点击测试的代码：

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，无法通过点击测试正常工作。

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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