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Added Rectangle.PerimeterPoint method for getting the point on the perimeter of a rectangle based on the given angle.

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This commit is contained in:
Richard Davey 2017-03-29 15:05:29 +01:00
parent 032f6e7084
commit b3b495e53c
2 changed files with 67 additions and 0 deletions
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66
v3/src/geom/rectangle/PerimeterPoint.js Normal file
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@ -0,0 +1,66 @@
var MATH_CONST = require('../../math/const');
// deg = degrees
var PerimeterPoint = function (rect, deg, out)
{
if (out === undefined) { out = { x: 0, y: 0 }; }
var theta = deg * MATH_CONST.DEG_TO_RAD;
while (theta < -Math.PI)
{
theta += MATH_CONST.PI2;
}
while (theta > Math.PI)
{
theta -= MATH_CONST.PI2;
}
var rectAtan = Math.atan2(rect.height, rect.width);
var tanTheta = Math.tan(theta);
var thetaBounds = Math.PI - rectAtan;
var region;
var xFactor = 1;
var yFactor = 1;
if (theta > -rectAtan && theta <= rectAtan)
{
region = 1;
yFactor = -1;
}
else if (theta > rectAtan && theta <= thetaBounds)
{
region = 2;
yFactor = -1;
}
else if (theta > thetaBounds || theta <= -thetaBounds)
{
region = 3;
xFactor = -1;
}
else
{
region = 4;
xFactor = -1;
}
out.x = rect.x + (rect.width / 2);
out.y = rect.y + (rect.height / 2);
if (region === 1 || region === 3)
{
out.x += xFactor * (rect.width / 2); // "Z0"
out.y += yFactor * (rect.width / 2) * tanTheta;
}
else
{
out.x += xFactor * (rect.height / (2 * tanTheta)); // "Z1"
out.y += yFactor * (rect.height / 2);
}
return out;
};
module.exports = PerimeterPoint;

1
v3/src/geom/rectangle/index.js
View file

@ -27,6 +27,7 @@ Rectangle.Offset = require('./Offset');
Rectangle.OffsetPoint = require('./OffsetPoint');
Rectangle.Overlaps = require('./Overlaps');
Rectangle.Perimeter = require('./Perimeter');
Rectangle.PerimeterPoint = require('./PerimeterPoint');
Rectangle.Random = require('./Random');
Rectangle.Scale = require('./Scale');
Rectangle.Union = require('./Union');