[css-transforms-2] First draft of the translate/rotate/scale properties.

Author: tabatkins

css-transforms-2/Overview.bs

@@ -15,15 +15,99 @@ Abstract:
 Abstract: This is a delta spec over CSS Transforms Level 1, while that spec is finishing standardization.
 </pre>
 
+<pre class="link-defaults">
+spec:css-2d-transforms-1;
+	type:property; text:transform
+	type:dfn; text: transformation matrix
+</pre>
+
+<!-- WTF, why does Bikeshed only shows these as existing the TR-level obsolete css-2d-transforms-1 draft? -->
+
 Introduction {#intro}
 =====================
 
 Introduction here.
 
 
+Individual Transform Properties: the 'translate', 'scale', and 'rotate' properties {#individual-transforms}
+===========================================================================================================
 
-Issue: Per <a href="https://lists.w3.org/Archives/Public/www-style/2015Mar/0371.html">https://lists.w3.org/Archives/Public/www-style/2015Mar/0371.html</a>,
-the WG resolved to add 'translate', 'scale', and 'rotate' properties.
+Fluff here.
+
+<pre class="propdef">
+Name: translate
+Value: [ <<length>> | <<percentage>> ] [[ <<length>> | <<percentage>> ] <<length>>? ]?
+Initial: 0
+Inherited: no
+Percentages: relative to the width of the containing block (for the first value) or the height (for the second value)
+Media: visual
+Computed Value: as specified, with lengths made absolute
+Animatable: as <<length>> or <<percentage>> list
+</pre>
+
+<pre class="propdef">
+Name: rotate
+Value: <<angle>> <<number>>{3}?
+Initial: 0deg
+Inherited: no
+Media: visual
+Animatable: as SLERP
+</pre>
+
+<pre class="propdef">
+Name: scale
+Value: <<number>>{1,3}
+Initial: 1
+Inherited: no
+Media: visual
+Animatable: as <<number>> list
+</pre>
+
+The 'translate', 'rotate', and 'scale' properties
+allow authors to specify simple transforms independently,
+in a way that maps to typical user interface usage,
+rather than having to remember the order in 'transform'
+that keeps the actions of ''transform()'', ''rotate()'' and ''scale()''
+independent and acting in screen coordinates.
+
+The 'translate' property accepts 1-3 values,
+each specifying a translation against one axis,
+in the order X, Y, then Z.
+Unspecified translations default to ''0px''.
+
+The 'rotate' property accepts an angle to rotate an element,
+and optionally an axis to rotate it around,
+specified as the X, Y, and Z lengths of an origin-anchored vector.
+If the axis is unspecified,
+it defaults to ''0 0 1'',
+causing a "2d rotation" in the plane of the screen.
+
+The 'scale' property accepts 1-3 values,
+each specifying a scale along one axis,
+in order X, Y, then Z.
+Unspecified scales default to ''1''.
+
+
+Current Transformation Matrix {#ctm}
+====================================
+
+The <a>transformation matrix</a> computation is amended to the following:
+
+The transformation matrix is computed from the 'transform', 'transform-origin', 'translate', 'rotate', 'scale', and 'motion' properties as follows:
+
+1. Start with the identity matrix.
+2. Translate by the computed X, Y, and Z values of 'transform-origin'.
+3. Translate by the computed X, Y, and Z values of 'translate'.
+4. Scale by the computed X, Y, and Z values of 'scale'.
+5. Rotate by the computed <<angle>> about the specified axis of 'rotate'.
+6. Translate and rotate by the transform specified by 'motion'.
+7. Multiply by each of the transform functions in 'transform' from left to right.
+8. Translate by the negated computed X, Y and Z values of 'transform-origin'.
+
+
+
+More Issues {#more-issues}
+==========================
 
 Issue: Per <a href="https://lists.w3.org/Archives/Public/www-style/2015Mar/0371.html">https://lists.w3.org/Archives/Public/www-style/2015Mar/0371.html</a>,
 the WG resolved to add a formula for decomposing a transform into a unified "scale"