HTML5画布drawImage使用点? [英] HTML5 canvas drawImage using points?

问题描述

我需要使用 4 个点来绘制图像.我将这 4 个点存储在一个数组中，这些位置会发生变化.现在我需要绘制一个反映这些位置的图像.context.drawImage 只接受 1 个位置.

I need to draw an image using 4 points. I have these 4 points stored in an array, these positions changes. Now I need to draw an image that reflects these positions. The context.drawImage only accepts 1 positon.

应该是这样，4个位置:

It should be like this, 4 positions:

x,y----------x,y
 |            |
 |            |
 |            |
 |            |
 |            |
x,y----------x,y

推荐答案

你要找的就是用 3D 渲染语言画一个四边形.

What you are looking for is called drawing a quad in 3D rendering language.

您通常将形状拆分为 2 个三角形(面)并使用纹理填充分别绘制它们.

You usually split up your shape to 2 triangles (faces) and draw them individually using a texture filling.

这里有一个(复杂的)解决方案:https://github.com/mrdoob/three.js/blob/master/src/renderers/CanvasRenderer.js#L838 Three.js 3D引擎使用2D <canvas>code> 作为渲染引擎.

Here is a (complex) solution for the problem: https://github.com/mrdoob/three.js/blob/master/src/renderers/CanvasRenderer.js#L838 Three.js 3D engine using 2D <canvas> as the rendering engine.

由于事情不是那么简单，我建议您使用 Three.js 或类似的包装器，它提供了对纹理面部操作的高级抽象.查看其他 Three.js 2D <canvas> 示例，您就会了解它的工作原理:

As the matter is not that straightforward I suggest you use Three.js or similar wrapper which provides high level abstraction over textured face operations. Check out other Three.js 2D <canvas> examples and you get the idea how it works:

http://mrdoob.github.com/three.js/

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