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Fix skew handling #1006

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Fix skew handling #1006

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51 changes: 36 additions & 15 deletions src/easeljs/geom/Matrix2D.js
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Original file line number Diff line number Diff line change
Expand Up @@ -260,14 +260,31 @@ this.createjs = this.createjs||{};
sin = 0;
}

var a = cos * scaleX;
var b = sin * scaleX;
var c = -sin * scaleY;
var d = cos * scaleY;

if (skewX || skewY) {
// TODO: can this be combined into a single append operation?
skewX *= Matrix2D.DEG_TO_RAD;
skewY *= Matrix2D.DEG_TO_RAD;
this.append(Math.cos(skewY), Math.sin(skewY), -Math.sin(skewX), Math.cos(skewX), x, y);
this.append(cos*scaleX, sin*scaleX, -sin*scaleY, cos*scaleY, 0, 0);
var b1 = Math.tan(skewY * Matrix2D.DEG_TO_RAD);
var c1 = Math.tan(skewX * Matrix2D.DEG_TO_RAD);
this.append(
a + c1 * b,
b1 * a + b,
c + c1 * d,
b1 * c + d,
x,
y
);
} else {
this.append(cos*scaleX, sin*scaleX, -sin*scaleY, cos*scaleY, x, y);
this.append(
a,
b,
c,
d,
x,
y
);
}

if (regX || regY) {
Expand Down Expand Up @@ -317,14 +334,18 @@ this.createjs = this.createjs||{};
// prepend the registration offset:
this.tx -= regX; this.ty -= regY;
}

var a = cos * scaleX;
var b = sin * scaleX;
var c = -sin * scaleY;
var d = cos * scaleY;

if (skewX || skewY) {
// TODO: can this be combined into a single prepend operation?
skewX *= Matrix2D.DEG_TO_RAD;
skewY *= Matrix2D.DEG_TO_RAD;
this.prepend(cos*scaleX, sin*scaleX, -sin*scaleY, cos*scaleY, 0, 0);
this.prepend(Math.cos(skewY), Math.sin(skewY), -Math.sin(skewX), Math.cos(skewX), x, y);
var b1 = Math.tan(skewY * Matrix2D.DEG_TO_RAD);
var c1 = Math.tan(skewX * Matrix2D.DEG_TO_RAD);
this.prepend(a+c1*b, b1*a+b, c+c1*d, b1*c+d, x, y);
} else {
this.prepend(cos*scaleX, sin*scaleX, -sin*scaleY, cos*scaleY, x, y);
this.prepend(a, b, c, d, x, y);
}
return this;
};
Expand Down Expand Up @@ -360,7 +381,7 @@ this.createjs = this.createjs||{};
p.skew = function(skewX, skewY) {
skewX = skewX*Matrix2D.DEG_TO_RAD;
skewY = skewY*Matrix2D.DEG_TO_RAD;
this.append(Math.cos(skewY), Math.sin(skewY), -Math.sin(skewX), Math.cos(skewX), 0, 0);
this.append(1, Math.tan(skewY), Math.tan(skewX), 1, 0, 0);
return this;
};

Expand Down Expand Up @@ -477,8 +498,8 @@ this.createjs = this.createjs||{};
target.scaleX = Math.sqrt(this.a * this.a + this.b * this.b);
target.scaleY = Math.sqrt(this.c * this.c + this.d * this.d);

var skewX = Math.atan2(-this.c, this.d);
var skewY = Math.atan2(this.b, this.a);
var skewX = Math.atan(this.c);
var skewY = Math.atan(this.b);

var delta = Math.abs(1-skewX/skewY);
if (delta < 0.00001) { // effectively identical, can use rotation:
Expand Down