如何在 Sceneform Android SDK 中将相机类型更改为正交? [英] How to change camera type to Orthographic in Sceneform Android SDK?

问题描述

在 SceneView(无 AR)中展示模型时，我想使用正交相机.在 API 中找不到这样做的方法.我是否遗漏了什么或缺少该功能?

解决方案

据我所知，没有 ORTHO 方法(cube frustum>) 用于当前 ARCore/Sceneform 中的相机投影.但是您可以通过 4x4 Matrix 自己制作.所以，你需要做的就是计算left、right、top、bottom、near 和 far 属性使用

您的投影矩阵 4x4 必须如下所示:

工作代码，其中 scaleFactor 是一个大约 1.3 的值，height/width 是 SceneView.

private fun buildOrthographicMatrix(right: Float,顶部:浮动，远:漂浮，附近:浮动):FloatArray {val 矩阵 = FloatArray(16)矩阵[0] = 1/右矩阵[1] = 0f矩阵[2] = 0f矩阵[3] = 0f矩阵[4] = 0f矩阵[5] = 1/顶部矩阵[6] = 0f矩阵[7] = 0f矩阵[8] = 0f矩阵[9] = 0f矩阵[10] = -2/(远-近)矩阵[11] = 0f矩阵[12] = 0f矩阵[13] = 0f矩阵[14] = -(远+近)/(远-近)矩阵[15] = 1f返回矩阵}val newMatrix = buildOrthographicMatrix(1f/scaleFactor,1f/scaleFactor * 高度/宽度，30楼，0.01f)camera.projectionMatrix = Matrix(newMatrix)

I'd like to use an Orthographic camera when presenting a model in SceneView (without AR). Couldn't find a way to do so in API. Am I missing something or the feature is missing?

解决方案

As far as I know, there's no ORTHO method (cube frustum) for camera projection in ARCore / Sceneform at the moment. But you can make it yourself via 4x4 Matrix. So, all you need to do is to calculate left, right, top, bottom, near and far properties using the following principles.

Here is how your projection matrix 4x4 must look like:

Edit: working code where scaleFactor is a value around 1.3 and height/width are properties of the SceneView.

private fun buildOrthographicMatrix(right: Float, 
                                      top: Float, 
                                      far: Float, 
                                     near: Float): FloatArray {
   val matrix = FloatArray(16)

   matrix[0] = 1 / right
   matrix[1] = 0f
   matrix[2] = 0f
   matrix[3] = 0f

   matrix[4] = 0f
   matrix[5] = 1 / top
   matrix[6] = 0f
   matrix[7] = 0f

   matrix[8] = 0f
   matrix[9] = 0f
   matrix[10] = -2 / (far - near)
   matrix[11] = 0f

   matrix[12] = 0f
   matrix[13] = 0f
   matrix[14] = -(far + near) / (far - near)
   matrix[15] = 1f

   return matrix
}

val newMatrix = buildOrthographicMatrix(1f / scaleFactor, 
                                        1f / scaleFactor * height / width, 
                                        30f, 
                                        0.01f)

camera.projectionMatrix = Matrix(newMatrix)

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