Using a Canvas element as a Texture in three.js
There are many situations in which I will want to have a texture to work with when it comes to working with materials in threejs. That is that when it comes to the various kinds of maps there are to work with in a material, such as diffuse maps, alpha maps, emissive maps, and so forth, one way or another I need to load or create a texture. One way to add a texture to a material would be to use the built in texture loader in the core of the threejs library, if I have some other preferred way to go about loading external images I can also use the THREE.Texture constructor directly to create a texture object from an Image object. However there is also the question of how to go about generating textures using a little javaScript code, and one way to go about creating a texture this way would be with a canvas element, the 2d drawing context of such a canvas element, and the THREE.CanvasTexture constructor
There is a whole lot of ground to cover when it comes to getting into this sort of thing if you do not have much experience working with canvas elements yet. The process of creating a texture with a canvas element is simple enough when it comes to the fact that I just need to pass the canvas element to a constructor function and the desired texture object is returned. However there are a whole bunch of other topics that branch off from this that have to do with canvas elements in detail, as well as other closely related threejs topics such as the uv attributes of buffer geometry instances that are used in conjunction with one or more materials. In this post I am mainly just going to be writing about using the built in constructors to create a texture with a canvas element. I might not get into detail about the 2d drawing context, but of course I will have to touch base on it to say the least.