Difference between revisions of "User:Regina/MYDrafts4"
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| − | The value <tt>rotate(a)</tt> is equivalent to the value <tt>matrix( cos(a) sin(a) −sin(a) cos(a) 0 0)</tt>. | + | The value <tt>rotate(a)</tt> is equivalent to the value <tt>matrix( cos(a) sin(a) −sin(a) cos(a) 0 0)</tt> with a in degrees. |
|- | |- | ||
| <tt>scale( sx [ sy ])</tt>, specifies a scale operation by sx and sy. | | <tt>scale( sx [ sy ])</tt>, specifies a scale operation by sx and sy. | ||
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Suggestion: | Suggestion: | ||
| − | The value <tt>skewX(a)</tt> is equivalent to the value <tt>matrix( 1 0 tan(a) 1 0 0)</tt>. | + | The value <tt>skewX(a)</tt> is equivalent to the value <tt>matrix( 1 0 tan(a) 1 0 0)</tt> with a in degrees. |
| − | In addition a picture is useful, because the term "shear mapping" is more common than "skew". | + | In addition a picture is useful, because the term "shear mapping" is more common than "skew". |
| + | |- | ||
| + | | <tt>skewY(skew-angle)</tt>, specifies a skew transformation by <tt>rotate-angle</tt> degrees along the y-axis. | ||
| + | | Same as skewX. Typo "rotate-angle" and unclear angle. | ||
| + | |||
| + | Suggestion: | ||
| + | |||
| + | The value <tt>skewY(a)</tt> is equivalent to the value <tt>matrix( 1 tan(a) 0 1 0 0)</tt> with a in degrees. | ||
| + | |||
| + | Bild | ||
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Revision as of 23:53, 8 August 2012
Problems With Angle Definitions in ODF1.2
Coordinate System
There are two common ways to orientate a Cartesian coordinate system
| mathematical orientation | Bild |
| screen orientation | Bild |
Only when the orientation is determined, terms like "clockwise" are unambigious. Such orientation rule is missing in ODF 1.2.
Suggestion:
If a rule refers to a two-dimensional coordinate system, a Cartesian coordinate system in screen orientation (see figure ##) is used. The directions "clockwise", "counter clockwise", and the edge descriptions "left", "top", "right" and "button" are accordingly defined as shown in figures [##] to [##].
| clockwise | Bild |
| counter clockwise | Bild |
| left, top, right, bottom | Bild |
Angles in Attribute draw:transform
These suggestions are all about section 19.228. (Because of the Wiki markup I skipped the characters < and >).
| Original | Problems and Suggestions |
|---|---|
| The whole original text is very near to SVG section 7, but a reference is missing. | |
| matrix(a b c d e f), specifies a transformation in the form of a transformation matrix of six values. "The values describe... | No problems, but the quotation mark before 'The values' has to be removed. |
| rotate(rotate-angle), specifies a rotation by rotate-angle degrees about the origin of the shapes coordinate system. | The orientation of the rotation is missing. I suggest not to use "clockwise" but to define it by an equivalent matrix.
Suggestion: The value rotate(a) is equivalent to the value matrix( cos(a) sin(a) −sin(a) cos(a) 0 0) with a in degrees. |
| scale( sx [ sy ]), specifies a scale operation by sx and sy. | "scale operation" is acceptable, but I suggest to give the equivalent matrix here too, to make it uniform.
Suggestion: The value scale( s ) is equivalent to the value matrix( s 0 0 s 0 0). The value scale( sx sy ) is equivalent to the value matrix( sx 0 0 sy 0 0). |
| skewX(skew-angle), specifies a skew transformation by rotate-angle degrees along the x-axis. | Typo: "rotate-angle" should be "skew-angle".
Here is neither clear between which rays the angle is measured, nor what direction is used. Suggestion: The value skewX(a) is equivalent to the value matrix( 1 0 tan(a) 1 0 0) with a in degrees. In addition a picture is useful, because the term "shear mapping" is more common than "skew". |
| skewY(skew-angle), specifies a skew transformation by rotate-angle degrees along the y-axis. | Same as skewX. Typo "rotate-angle" and unclear angle.
Suggestion: The value skewY(a) is equivalent to the value matrix( 1 tan(a) 0 1 0 0) with a in degrees. Bild |
