From: Dirk Schulze <dschulze@adobe.com>

Date: Mon, 12 Nov 2012 10:56:21 -0800

To: Boris Zbarsky <bzbarsky@MIT.EDU>

CC: "www-style@w3.org" <www-style@w3.org>

Message-ID: <A14D79E3-7DDF-4D49-B790-7153C1674EB5@adobe.com>

Date: Mon, 12 Nov 2012 10:56:21 -0800

To: Boris Zbarsky <bzbarsky@MIT.EDU>

CC: "www-style@w3.org" <www-style@w3.org>

Message-ID: <A14D79E3-7DDF-4D49-B790-7153C1674EB5@adobe.com>

On Nov 12, 2012, at 9:36 AM, Boris Zbarsky <bzbarsky@MIT.EDU> wrote: > I would suggest changing step 3 of the above steps to something like this: > > 3. Multiply on the right by the product of the matrices corresponding > to the transform functions in the 'transform' property, in the order > they are given. > > or something along those lines. I _think_ this is correct; I haven't > triple checked the left vs right in there. Might be worth doing that. This confuses me a bit. But am not sure about which part I am confused. Lets say you have the following transform function list for the transform property: transform: translate() rotate() scale() Each transform function will be transformed to a matrix which would look like transform: A B C where A is equivalent to translate() B is equivalent to rotate() C is equivalent to scale() The transform origin is 'center'. Therefore, we need to translate before applying the transform function lists. Lets go step by step according to the spec: 1. Start with the identity matrix. We create the identical transformation matrix I: T = I. 2. Translate by the computed X, Y and Z values of ‘transform-origin’ Create a translation matrix and multiply with I: T = I * Trans 3. Multiply by each of the transform functions in ‘transform’ property from left to right T = I * Trans * A * B * C 4. Translate by the negated computed X, Y and Z values of ‘transform-origin’ T = I * Trans * A * B * C * TransBack T is the local transformation matrix (or just transformation matrix). To get the CTM, you need to accumulate all transformation matrices. Is the part that confuses you the part with A * B * C? Or how to multiply these transformation matrices to the identical transform with the translation (I * Trans * A * B * C)? Do you disagree with the order in general? Greetings, DirkReceived on Monday, 12 November 2012 18:56:48 UTC

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