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

问题描述

我需要使用4点绘制图像。我有这4个点存储在数组中，这些位置改变。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。

应该是这样，4个位置：

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

你通常把你的形状分成2个三角形（面）

这里是一个（复杂的）问题解决方案： https://github.com/mrdoob/three.js/blob/master/src/renderers/CanvasRenderer.js# L838 Three.js 3D引擎使用2D < canvas> 作为渲染引擎。

事情不是那么直接我建议你使用Three.js或类似的包装器提供高级抽象纹理面部操作。查看其他Three.js 2D < canvas> 示例，你会得到它的工作原理：

a href =http://mrdoob.github.com/three.js/ =nofollow> http://mrdoob.github.com/three.js/

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.

It should be like this, 4 positions:

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

解决方案

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

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

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.

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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