THREEJS:从 Z-Up 坐标系到 Y-Up 坐标系的矩阵

问题描述

我正在尝试导出一系列转换矩阵以在 ThreeJS 中为对象设置动画.这些转换是从Rhino中提取出来的，一个Z-Up Modeler，需要放到ThreeJS中，也就是Y-Up.我发现了一个类似的问题 在这个网站上，但答案似乎不正确，因为我的转换没有延续.

I am trying to export a series of Transformation Matrices to animate objects in ThreeJS. These transformation are extracted from Rhino, a Z-Up Modeler and need to be placed into ThreeJS, which is Y-Up. I've found a similar question on this site, but the answer does not appear to be correct because my transformations don't carry over.

谁能将下面的通用 4x4 矩阵从 Z-Up 坐标系转换为 Y-Up 坐标系?

Can anyone translate the generic 4x4 matrix below from a Z-Up coordinate system to a Y-Up Coordinate System?

{ a, b, c, d }
{ e, f, g, h }
{ i, j, k, l }
{ m, n, o, p }

推荐答案

好吧，我想我有一个可行的解决方案:

Alright, I think I have a working solution:

如果几何从 Z Up Environment 导出(您没有在设置中翻转 YZ)，您可以将其导入 THREEjs 并使用此矩阵更正 YZ 差异(链接):

If the geometry is exported as is from the Z Up Environment (you are not flipping the YZ in your settings), you can import it into THREEjs and correct the YZ Discrepancy with this matrix (link) :

        objectid.matrixWorldNeedsUpdate=true;
        objectid.matrix.set
        (
            1,  0,  0,  0,
            0,  0,  1,  0,
            0,  -1, 0,  0,
            0,  0,  0,  1
        );
        objectid.updateMatrixWorld();

经过这个转换，写这个 后，您正在将转换应用于导入的转换.这将翻转第二行和第三行并翻转第二列和第三列:

After this tranformation, wrt this post, you're applying the transition to the imported transformation. This flips the second and third rows AND flips the second and third columns:

{ a, b, c, d }
{ e, f, g, h }
{ i, j, k, l }
{ m, n, o, p }

到

{ a, c, b, d }
{ i, k, j, l }
{ e, g, f, h }
{ m, o, n, p }

当我从 Rhino 导出 OBJ 时，我最初是在翻转 YZ，所以转换是在不同的几何体上执行的.当 YZ 翻转应用于 javascript 端时，它现在可以工作了.

I was originally flipping the YZ when I exported the OBJ from Rhino, so the transformation was performing on different geometry. It's working now when the YZ flip is applied on the javascript side.

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