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133 lines
3.5 KiB
HTML
133 lines
3.5 KiB
HTML
2 months ago
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="utf-8" />
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<base href="../../../" />
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<script src="page.js"></script>
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<link type="text/css" rel="stylesheet" href="page.css" />
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</head>
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<body>
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<h1>[name]</h1>
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<p class="desc">
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A class representing a 2x2
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[link:https://en.wikipedia.org/wiki/Matrix_(mathematics) matrix].
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</p>
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<h2>Code Example</h2>
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<code>
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const m = new Matrix2();
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</code>
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<h2>A Note on Row-Major and Column-Major Ordering</h2>
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<p>
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The constructor and [page:set]() method take arguments in
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[link:https://en.wikipedia.org/wiki/Row-_and_column-major_order#Column-major_order row-major]
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order, while internally they are stored in the [page:.elements elements]
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array in column-major order.<br /><br />
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This means that calling
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<code>
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m.set( 11, 12,
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21, 22 );
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</code>
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will result in the [page:.elements elements] array containing:
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<code>
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m.elements = [ 11, 21,
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12, 22 ];
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</code>
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and internally all calculations are performed using column-major ordering.
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However, as the actual ordering makes no difference mathematically and
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most people are used to thinking about matrices in row-major order, the
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three.js documentation shows matrices in row-major order. Just bear in
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mind that if you are reading the source code, you'll have to take the
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[link:https://en.wikipedia.org/wiki/Transpose transpose] of any matrices
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outlined here to make sense of the calculations.
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</p>
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<h2>Constructor</h2>
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<h3>[name]( [param:Number n11], [param:Number n12],
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[param:Number n21], [param:Number n22] )</h3>
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<p>
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Creates a 2x2 matrix with the given arguments in row-major order. If no arguments are provided, the constructor initializes
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the [name] to the 3x3 [link:https://en.wikipedia.org/wiki/Identity_matrix identity matrix].
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</p>
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<h2>Properties</h2>
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<h3>[property:Array elements]</h3>
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<p>
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A [link:https://en.wikipedia.org/wiki/Row-_and_column-major_order column-major] list of matrix values.
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</p>
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<h2>Methods</h2>
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<h3>
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[method:this fromArray]( [param:Array array], [param:Integer offset] )
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</h3>
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<p>
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[page:Array array] - the array to read the elements from.<br />
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[page:Integer offset] - (optional) index of first element in the array.
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Default is `0`.<br /><br />
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Sets the elements of this matrix based on an array in
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[link:https://en.wikipedia.org/wiki/Row-_and_column-major_order#Column-major_order column-major] format.
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</p>
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<h3>[method:this identity]()</h3>
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<p>
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Resets this matrix to the 2x2 identity matrix:
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</p>
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<math display="block">
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<mrow>
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<mo>[</mo>
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<mtable>
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<mtr>
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<mtd><mn>1</mn></mtd>
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<mtd><mn>0</mn></mtd>
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</mtr>
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<mtr>
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<mtd><mn>0</mn></mtd>
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<mtd><mn>1</mn></mtd>
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</mtr>
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</mtable>
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<mo>]</mo>
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</mrow>
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</math>
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<h3>
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[method:this set]( [param:Float n11], [param:Float n12], [param:Float n21], [param:Float n22] )
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</h3>
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<p>
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Sets the 2x2 matrix values to the given
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[link:https://en.wikipedia.org/wiki/Row-_and_column-major_order row-major]
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sequence of values:
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</p>
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<math display="block">
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<mrow>
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<mo>[</mo>
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<mtable>
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<mtr>
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<mtd><mi>n11</mi></mtd>
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<mtd><mi>n12</mi></mtd>
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</mtr>
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<mtr>
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<mtd><mi>n21</mi></mtd>
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<mtd><mi>n22</mi></mtd>
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</mtr>
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</mtable>
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<mo>]</mo>
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</mrow>
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</math>
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<h2>Source</h2>
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<p>
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[link:https://github.com/mrdoob/three.js/blob/master/src/[path].js src/[path].js]
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</p>
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</body>
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</html>
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