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250 lines
8.3 KiB
250 lines
8.3 KiB
<!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 3x3 [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 Matrix3();
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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 [page:set]() method takes arguments in [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] 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, 13,
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21, 22, 23,
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31, 32, 33 );
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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, 31,
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12, 22, 32,
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13, 23, 33 ];
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</code>
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and internally all calculations are performed using column-major ordering. However, as the actual ordering
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makes no difference mathematically and most people are used to thinking about matrices in row-major order,
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the three.js documentation shows matrices in row-major order. Just bear in mind that if you are reading the source
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code, you'll have to take the [link:https://en.wikipedia.org/wiki/Transpose transpose] of any matrices 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]()</h3>
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<p>
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Creates and initializes the [name] to the 3x3
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[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]
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list of matrix values.
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</p>
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<h2>Methods</h2>
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<h3>[method:Matrix3 clone]()</h3>
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<p>Creates a new Matrix3 and with identical elements to this one.</p>
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<h3>[method:this copy]( [param:Matrix3 m] )</h3>
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<p>Copies the elements of matrix [page:Matrix3 m] into this matrix.</p>
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<h3>[method:Float determinant]()</h3>
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<p>
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Computes and returns the
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[link:https://en.wikipedia.org/wiki/Determinant determinant] of this matrix.
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</p>
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<h3>[method:Boolean equals]( [param:Matrix3 m] )</h3>
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<p>Return true if this matrix and [page:Matrix3 m] are equal.</p>
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<h3>[method:this extractBasis]( [param:Vector3 xAxis], [param:Vector3 yAxis], [param:Vector3 zAxis] )</h3>
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<p>
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Extracts the [link:https://en.wikipedia.org/wiki/Basis_(linear_algebra) basis] of this
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matrix into the three axis vectors provided. If this matrix is:
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<code>
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a, b, c,
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d, e, f,
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g, h, i
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</code>
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then the [page:Vector3 xAxis], [page:Vector3 yAxis], [page:Vector3 zAxis] will be set to:
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<code>
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xAxis = (a, d, g)
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yAxis = (b, e, h)
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zAxis = (c, f, i)
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</code>
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</p>
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<h3>[method:this fromArray]( [param:Array array], [param:Integer offset] )</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. 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 invert]()</h3>
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<p>
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Inverts this matrix, using the [link:https://en.wikipedia.org/wiki/Invertible_matrix#Analytic_solution analytic method].
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You can not invert with a determinant of zero. If you attempt this, the method produces a zero matrix instead.
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</p>
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<h3>[method:this getNormalMatrix]( [param:Matrix4 m] )</h3>
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<p>
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[page:Matrix4 m] - [page:Matrix4]<br /><br />
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Sets this matrix as the upper left 3x3 of the [link:https://en.wikipedia.org/wiki/Normal_matrix normal matrix]
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of the passed [page:Matrix4 matrix4]. The normal matrix is the [link:https://en.wikipedia.org/wiki/Invertible_matrix inverse] [link:https://en.wikipedia.org/wiki/Transpose transpose]
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of the matrix [page:Matrix4 m].
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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 3x3 identity matrix:
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<code>
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1, 0, 0
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0, 1, 0
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0, 0, 1
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</code>
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</p>
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<h3>[method:this makeRotation]( [param:Float theta] )</h3>
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<p>
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[page:Float theta] — Rotation angle in radians. Positive values rotate counterclockwise.<br /><br />
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Sets this matrix as a 2D rotational transformation by [page:Float theta] radians.
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The resulting matrix will be:
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<code>
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cos(θ) -sin(θ) 0
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sin(θ) cos(θ) 0
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0 0 1
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</code>
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</p>
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<h3>[method:this makeScale]( [param:Float x], [param:Float y] )</h3>
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<p>
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[page:Float x] - the amount to scale in the X axis.<br />
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[page:Float y] - the amount to scale in the Y axis.<br />
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Sets this matrix as a 2D scale transform:
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<code>
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x, 0, 0,
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0, y, 0,
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0, 0, 1
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</code>
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</p>
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<h3>[method:this makeTranslation]( [param:Float x], [param:Float y] )</h3>
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<p>
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[page:Float x] - the amount to translate in the X axis.<br />
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[page:Float y] - the amount to translate in the Y axis.<br />
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Sets this matrix as a 2D translation transform:
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<code>
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1, 0, x,
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0, 1, y,
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0, 0, 1
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</code>
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</p>
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<h3>[method:this multiply]( [param:Matrix3 m] )</h3>
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<p>Post-multiplies this matrix by [page:Matrix3 m].</p>
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<h3>[method:this multiplyMatrices]( [param:Matrix3 a], [param:Matrix3 b] )</h3>
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<p>Sets this matrix to [page:Matrix3 a] x [page:Matrix3 b].</p>
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<h3>[method:this multiplyScalar]( [param:Float s] )</h3>
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<p>Multiplies every component of the matrix by the scalar value *s*.</p>
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<h3>[method:this rotate]( [param:Float theta] )</h3>
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<p>Rotates this matrix by the given angle (in radians).</p>
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<h3>[method:this scale]( [param:Float sx], [param:Float sy] )</h3>
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<p>Scales this matrix with the given scalar values.</p>
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<h3>[method:this set]( [param:Float n11], [param:Float n12], [param:Float n13], [param:Float n21], [param:Float n22], [param:Float n23], [param:Float n31], [param:Float n32], [param:Float n33] )</h3>
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<p>
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[page:Float n11] - value to put in row 1, col 1.<br />
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[page:Float n12] - value to put in row 1, col 2.<br />
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...<br />
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...<br />
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[page:Float n32] - value to put in row 3, col 2.<br />
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[page:Float n33] - value to put in row 3, col 3.<br /><br />
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Sets the 3x3 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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<h3>[method:this premultiply]( [param:Matrix3 m] )</h3>
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<p>Pre-multiplies this matrix by [page:Matrix3 m].</p>
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<h3>[method:this setFromMatrix4]( [param:Matrix4 m] )</h3>
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<p>Set this matrix to the upper 3x3 matrix of the Matrix4 [page:Matrix4 m].</p>
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<h3>[method:this setUvTransform]( [param:Float tx], [param:Float ty], [param:Float sx], [param:Float sy], [param:Float rotation], [param:Float cx], [param:Float cy] )</h3>
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<p>
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[page:Float tx] - offset x<br />
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[page:Float ty] - offset y<br />
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[page:Float sx] - repeat x<br />
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[page:Float sy] - repeat y<br />
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[page:Float rotation] - rotation, in radians. Positive values rotate counterclockwise<br />
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[page:Float cx] - center x of rotation<br />
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[page:Float cy] - center y of rotation<br /><br />
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Sets the UV transform matrix from offset, repeat, rotation, and center.
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</p>
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<h3>[method:Array toArray]( [param:Array array], [param:Integer offset] )</h3>
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<p>
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[page:Array array] - (optional) array to store the resulting vector in. If not given a new array will be created.<br />
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[page:Integer offset] - (optional) offset in the array at which to put the result.<br /><br />
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Writes the elements of this matrix to 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 translate]( [param:Float tx], [param:Float ty] )</h3>
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<p>Translates this matrix by the given scalar values.</p>
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<h3>[method:this transpose]()</h3>
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<p>[link:https://en.wikipedia.org/wiki/Transpose Transposes] this matrix in place.</p>
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<h3>[method:this transposeIntoArray]( [param:Array array] )</h3>
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<p>
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[page:Array array] - array to store the resulting vector in.<br /><br />
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[link:https://en.wikipedia.org/wiki/Transpose Transposes] this matrix into the supplied array,
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and returns itself unchanged.
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</p>
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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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