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(不带AR)中展示模型时，我想使用正交摄影机.找不到在API中执行此操作的方法.我是否缺少某些东西或功能缺失?

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?

推荐答案

据我所知，相机投影没有 ORTHO 方法(立方体截头圆锥体)现在在ARCore/Sceneform中.但是您可以通过4x4矩阵自己制作.因此，您要做的就是使用

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.

这是您的4x4投影矩阵的外观:

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

希望这会有所帮助.

工作代码，其中scaleFactor是大约1的值，而height/width是SceneView的属性.

working code where scaleFactor is a value around 1 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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