change-mat4-coordinate-system

change-mat4-coordinate-system

Convert a 4x4 column major matrix from left handed to right handed coordinate system

Background / Initial Motivation

Blender exports bone matrices in using a handed coordinate system, but WebGL uses a left handed coordinate system.

I used to know change coordinate systems by changing my final gl_Position's coordinates, but I now need to manipulate coordinates before I get to my vertex shader (to find the location and rotation of a bone so that I can render something on top of it). This module helps me with converting everything to left handed during compile time, so that I don't need to do any coordinate system conversion during runtime.

To Install

$ npm install --save change-mat4-coordinate-system

Usage

var changeMat4Coords = require('change-mat4-coordinate-system')

// Don't worry, both rotations and translations will be converted.
// It's just easier to demonstrate translations here.
var rightHandedMatrix = [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 5, 1, 1]

var leftHandedMatrix = changeMat4Coords.rightToLeft(rightHandedMatrix)

console.log(leftHandedMatrix)
// [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, -5, 1]

License

MIT