tranny

A little library for converting compound CSS transforms into their matrix equivalents.

usage

 
# using the default matrix 
new Tranny
 
# or using a custom 4x4 matrix (meaning some transformations are already applied) 
matrix = [
    [1, 2, 3, 4]
    [5, 6, 7, 8]
    [9, 0, 1, 2]
    [3, 4, 5, 6]
]
new Tranny matrix
 

example

tranny = new Tranny
 
tranny
 
# set some transforms 
.rotate '90deg'
.translate3d 50, 100, 200
 
# get a matrix back 
tranny.getMatrix()
 
 
#=> [ 
#		[9.870993963020204, 0.7, 0, 0], 
#		[-0.5, 0, 0, 0], 
#		[0, 0, 1, 0], 
#		[443.54969815101026, 35, 200, 1] 
#	] 
 
# .. or as a CSS property 
tranny.getMatrixCSS()
 
#=> "matrix3d(9.870993963020204, 0.7, 0, 0, -0.5, 0, 0, 0, 0, 0, 1, 0, 443.54969815101026, 35, 200, 1)" 
 
# set a new base matrix (on the basis of which transforms are applied) 
tranny.matrix [
    [3, 1, 4, 1]
    [5, 9, 2, 6]
    [5, 3, 5, 8]
    [9, 7, 9, 3]
]
 

supported transforms

• perspective
• rotate
• rotateX
• rotateY
• rotateZ
• rotate3d
• scale
• scaleX
• scaleY
• scaleZ
• scale3d
• skew
• skewX
• skewY
• translate
• translateX
• translateY
• translateZ
• translate3d

why not use actual matricies?

If you're performing caculations dozens of times per second (in the case of animations. 60 times per second), performance is essential. Not only do we need to be able to perform calculations for complex compound 3D transforms at 60FPS, but we need to leave head room for any precursor computations, as well as compositing and painting (ideally, the last two should take place on the GPU). Performing the calculations ourselves (instead of leaving it to the CSS engine) gives us finer control over where (CPU vs. GPU, this thread vs. a WebWorker, sync vs. async) and when (precomputed, partially applied, realtime) computation occurs.

see also

• http://www.w3.org/TR/css3-transforms/#transform-functions
• http://www.w3.org/TR/SVG/coords.html#TransformMatrixDefined
• http://dev.opera.com/articles/view/understanding-the-css-transforms-matrix/
• http://dev.opera.com/articles/view/understanding-3d-transforms/
• http://inside.mines.edu/~gmurray/ArbitraryAxisRotation/
• http://stackoverflow.com/a/15208858/435124
• http://desandro.github.io/3dtransforms/docs/perspective.html

todo

• accept alternative units for scalars (%, em, pt, etc.)