added invert/determinant
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Tristan Campbell
parent
3c3208618e
commit
8b66ea95a5
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@ -292,8 +292,24 @@ public class Matrix2f extends Matrix {
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* Invert this matrix
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* @return this
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*/
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public Matrix invert() {
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assert false : "Not implemented yet!";
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public Matrix invert()
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{
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/*
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inv(A) = 1/det(A) * adj(A);
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*/
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float determinant = m00 * m11 - m01*m10;
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float t00 = m11/determinant;
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float t01 = -m01/determinant;
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float t11 = m00/determinant;
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float t10 = -m10/determinant;
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m00 = t00;
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m01 = t01;
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m10 = t10;
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m11 = t11;
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return this;
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}
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@ -357,8 +373,7 @@ public class Matrix2f extends Matrix {
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* @see org.lwjgl.vector.Matrix#determinant()
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*/
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public float determinant() {
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assert false : "Not implemented yet!";
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return 0;
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return m00 * m11 - m01*m10;
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}
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}
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@ -365,8 +365,55 @@ public class Matrix3f extends Matrix {
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* Invert this matrix
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* @return this
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*/
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public Matrix invert() {
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assert false : "Not implemented yet!";
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public Matrix invert()
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{
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float determinant = m00 * (m11 * m22 - m12 * m21)
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+ m01 * (m12 * m20 - m10 * m22)
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+ m02 * (m10 * m21 - m11 * m20);
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if (determinant == 1)
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// matrix is proper orthogonal
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transpose();
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else if (determinant == -1)
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{ // matrix is improper orthogonal
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transpose();
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negate();
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}
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else if (determinant != 0)
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{
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// do it the ordinary way
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/* inv(A) = 1/det(A) * adj(T), where adj(T) = transpose(Conjugate Matrix)
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m00 m01 m02
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m10 m11 m12
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m20 m21 m22
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*/
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// get the conjugate matrix
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float t00 = m11 * m22 - m12* m22;
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float t01 = - m10 * m22 + m12 *m20;
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float t02 = m10 * m21 - m11 * m20;
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float t10 = - m01 * m22 + m02 * m21;
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float t11 = m00 * m22 - m02 * m20;
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float t12 = - m00 * m21 + m01 * m20;
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float t20 = m01 * m12 - m02 * m11;
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float t21 = -m00 * m12 + m02 * m10;
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float t22 = m00 * m11 - m01 * m10;
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m00 = t00/determinant;
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m11 = t11/determinant;
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m22 = t22/determinant;
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m01 = t10/determinant;
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m10 = t01/determinant;
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m20 = t02/determinant;
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m02 = t20/determinant;
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m12 = t21/determinant;
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m21 = t12/determinant;
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}
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return this;
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}
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@ -553,13 +553,84 @@ public class Matrix4f extends Matrix {
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return f;
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}
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/**
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* Calculate the determinant of a 3x3 matrix
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* @return result
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*/
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private float determinant3x3(float t00, float t01, float t02,
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float t10, float t11, float t12,
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float t20, float t21, float t22)
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{
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return t00 * (t11 * t22 - t12 * t21)
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+ t01 * (t12 * t20 - t10 * t22)
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+ t02 * (t10 * t21 - t11 * t20);
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}
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/**
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* Invert this matrix
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* @return this
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*/
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public Matrix invert() {
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assert false : "Not implemented yet!";
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float determinant = determinant();
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if (determinant == 1)
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// proper orthogonal
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transpose();
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else if (determinant == -1)
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{ // improper orthogonal
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transpose();
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negate();
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}
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else if (determinant != 0)
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{
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/*
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m00 m01 m02 m03
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m10 m11 m12 m13
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m20 m21 m22 m23
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m30 m31 m32 m33
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*/
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// first row
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float t00 = determinant3x3( m11, m12, m13, m21, m22, m23, m31, m32, m33 );
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float t01 = -determinant3x3(m10, m12, m13, m20, m22, m23, m30, m32, m33 );
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float t02 = determinant3x3( m10, m11, m13, m20, m21, m23, m30, m31, m33 );
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float t03 = -determinant3x3(m10, m11, m12, m20, m21, m22, m30, m31, m32 );
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// second row
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float t10 = -determinant3x3(m01, m02, m03, m21, m22, m23, m31, m32, m33 );
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float t11 = determinant3x3( m00, m02, m03, m20, m22, m23, m30, m32, m33 );
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float t12 = -determinant3x3(m00, m01, m03, m20, m21, m23, m30, m31, m33 );
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float t13 = determinant3x3( m00, m01, m02, m20, m21, m22, m30, m31, m32 );
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// third row
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float t20 = determinant3x3( m01, m02, m03, m11, m12, m13, m31, m32, m33 );
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float t21 = -determinant3x3(m00, m02, m03, m10, m12, m13, m30, m32, m33 );
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float t22 = determinant3x3( m00, m01, m03, m10, m11, m13, m30, m31, m33 );
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float t23 = -determinant3x3(m00, m01, m02, m10, m11, m12, m30, m31, m32 );
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// fourth row
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float t30 = -determinant3x3(m01, m02, m03, m11, m12, m13, m21, m22, m23 );
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float t31 = determinant3x3( m00, m02, m03, m10, m12, m13, m20, m22, m23 );
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float t32 = -determinant3x3(m00, m01, m03, m10, m11, m13, m20, m21, m23 );
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float t33 = determinant3x3( m00, m01, m02, m10, m11, m12, m20, m21, m22 );
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// transpose and divide by the determinant
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m00 = t00/determinant;
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m11 = t11/determinant;
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m22 = t22/determinant;
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m33 = t33/determinant;
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m01 = t10/determinant;
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m10 = t01/determinant;
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m20 = t02/determinant;
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m02 = t20/determinant;
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m12 = t21/determinant;
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m21 = t12/determinant;
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m03 = t30/determinant;
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m30 = t03/determinant;
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m13 = t31/determinant;
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m31 = t13/determinant;
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m32 = t23/determinant;
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m23 = t32/determinant;
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}
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return this;
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}
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