Blame c++/vector/matrix.cpp
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#include "matrix.h"
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Matrix
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Matrix::get_inverted() const {
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Real d = det();
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if (equal(d, 0)) {
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// try to make back transform for X-axis
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if (equal(m02, 0) && equal(m10, 0) && equal(m11, 0) && equal(m12, 0) && equal(m22, 1)) {
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d = axis_x().lensqr();
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if (d > precision) {
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d = 1.0/d;
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return Matrix(
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d*m00, 0, 0,
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d*m01, 0, 0,
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-d*(m20*m00 + m21*m01), 0, 1 );
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}
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}
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// try to make back transform for Y-axis
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if (equal(m00, 0) && equal(m01, 0) && equal(m02, 0) && equal(m12, 0) && equal(m22, 1)) {
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d = axis_y().lensqr();
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if (d > precision) {
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d = 1/d;
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return Matrix(
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0, d*m10, 0,
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0, d*m11, 0,
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0, -d*(m20*m10 + m21*m11), 1 );
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}
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}
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// give up
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return Matrix( 0, 0, 0,
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0, 0, 0,
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0, 0, 0 );
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}
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// proper inversion
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Real p = 1/d, m = -p;
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return Matrix(
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p*(m11*m22 - m12*m21), // row0
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m*(m01*m22 - m02*m21),
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p*(m01*m12 - m02*m11),
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m*(m10*m22 - m12*m20), // row1
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p*(m00*m22 - m02*m20),
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m*(m00*m12 - m02*m10),
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p*(m10*m21 - m11*m20), // row2
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m*(m00*m21 - m01*m20),
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p*(m00*m11 - m01*m10) );
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}
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