threejs canvas todataurl为空 [英] threejs canvas todataurl is blank

问题描述

好的，我知道canvas.toDataUrl()会生成png格式的图像.但是，当我尝试从 http://threejs.org/examples/#webgl_lines_sphere 获取图片时.我所看到的只是镀铬的黑色图像.复制步骤-

Okay, I know that canvas.toDataUrl() will produce an image in png format. However, when I try to get the image from http://threejs.org/examples/#webgl_lines_sphere. All I see is a black image on chrome. To replicate the steps -

1)打开开发者控制台，然后选择canvas元素. 2)canvas = $0 3)context = canvas.getContext('webgl', {preserveDrawingBuffer: true}) 4)img = canvas.toDataUrl() 5)document.write('<img src="'+img+'"/>')

1) Open dev console and select the canvas element. 2) canvas = $0 3) context = canvas.getContext('webgl', {preserveDrawingBuffer: true}) 4) img = canvas.toDataUrl() 5) document.write('<img src="'+img+'"/>')

图像为空白. 但是，我尝试在链接 http://threejs.org/examples/#canvas_geometry_cube 上使用其他画布. .请执行以下步骤进行复制.

The image is blank. However, I tried with a different canvas at link http://threejs.org/examples/#canvas_geometry_cube. Please do the following steps to replicate.

1)打开开发者控制台，然后选择canvas元素. 2)canvas = $0 3)context = canvas.getContext('2d', {preserveDrawingBuffer: true}) 4)img = canvas.toDataUrl() 5)document.write('<img src="'+img+'"/>')

1) Open dev console and select the canvas element. 2) canvas = $0 3) context = canvas.getContext('2d', {preserveDrawingBuffer: true}) 4) img = canvas.toDataUrl() 5) document.write('<img src="'+img+'"/>')

这给出了预期的结果.为什么会有区别?又如何避免获取第一张图片?

This gave the expected result. Why is there a difference and how can this be avoided to retrieve first image too?

推荐答案

我也得到了纯黑色图像.

I was also getting a solid black image.

我以前的代码是:

this.renderer = new THREE.WebGLRenderer({premultipliedAlpha: false});

我已将THREE.WebGLRenderer中的参数更改为:

I have changed the parameter in the THREE.WebGLRenderer to:

this.renderer = new THREE.WebGLRenderer({preserveDrawingBuffer: true});

我正在拍摄快照.

希望有帮助.

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