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Implement Mat4x4 Inverse() (Yikes!!!)

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josh
2024-01-31 20:05:31 -05:00
parent 40e69d5c4f
commit 5080305965
2 changed files with 51 additions and 3 deletions
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2
include/J3ML/Geometry/Capsule.h
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@@ -16,7 +16,7 @@ namespace Geometry
Capsule();
Capsule(const LineSegment& endPoints, float radius);
Capsule(const Vector3& bottomPt, const Vector3& topPt, float radius);
bool IsDegenerate()const;
bool IsDegenerate() const;
float Height() const;
float Diameter() const;
Vector3 Bottom() const;

52
include/J3ML/LinearAlgebra/Matrix4x4.h
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@@ -12,7 +12,7 @@ namespace LinearAlgebra {
* The elements of this matrix are
* m_00, m_01, m_02, m_03
* m_10, m_11, m_12, m_13
* m_20, m_21, m_22, am_23,
* m_20, m_21, m_22, m_23,
* m_30, m_31, m_32, m_33
*
* The element m_yx is the value on the row y and column x.
@@ -107,7 +107,53 @@ namespace LinearAlgebra {
// If the determinant is nonzero, this matrix is invertible.
float Determinant() const;
Matrix4x4 Inverse() const;
Matrix4x4 Inverse() const
{
// Compute the inverse directly using Cramer's rule
// Warning: This method is numerically very unstable!
float d = Determinant();
d = 1.f / d;
// TODO: Subtract 1 from each entry index
float a11 = At(0, 0);
float a12 = At(0, 1);
float a13 = At(0, 2);
float a14 = At(0, 3);
float a21 = At(1, 0);
float a22 = At(1, 1);
float a23 = At(1, 2);
float a24 = At(1, 3);
float a31 = At(2, 0);
float a32 = At(2, 1);
float a33 = At(2, 2);
float a34 = At(2, 3);
float a41 = At(3, 0);
float a42 = At(3, 1);
float a43 = At(3, 2);
float a44 = At(3, 3);
Matrix4x4 i = {
d * (a22*a33*a44 + a23*a34*a42 + a24*a32*a43 - a22*a34*a43 - a23*a32*a44 - a24*a33*a42),
d * (a12*a34*a43 + a13*a32*a44 + a14*a33*a42 - a12*a33*a44 - a13*a34*a42 - a14*a32*a43),
d * (a12*a23*a44 + a13*a24*a42 + a14*a22*a43 - a12*a24*a43 - a13*a22*a44 - a14*a23*a42),
d * (a12*a24*a33 + a13*a22*a34 + a14*a23*a32 - a12*a23*a34 - a13*a24*a32 - a14*a22*a33),
d * (a21*a34*a43 + a23*a31*a44 + a24*a33*a41 - a21*a33*a44 - a23*a34*a41 - a24*a31*a43),
d * (a11*a33*a44 + a13*a34*a41 + a14*a31*a43 - a11*a34*a43 - a13*a31*a44 - a14*a33*a41),
d * (a11*a24*a43 + a13*a21*a44 + a14*a23*a41 - a11*a23*a44 - a13*a24*a41 - a14*a21*a43),
d * (a11*a23*a34 + a13*a24*a31 + a14*a21*a33 - a11*a24*a33 - a13*a21*a34 - a14*a23*a31),
d * (a21*a32*a44 + a22*a34*a41 + a24*a31*a42 - a21*a34*a42 - a22*a31*a44 - a24*a32*a41),
d * (a11*a34*a42 + a12*a31*a44 + a14*a32*a41 - a11*a32*a44 - a12*a34*a41 - a14*a31*a42),
d * (a11*a22*a44 + a12*a24*a41 + a14*a21*a42 - a11*a24*a42 - a12*a21*a44 - a14*a22*a41),
d * (a11*a24*a32 + a12*a21*a34 + a14*a22*a31 - a11*a22*a34 - a12*a24*a31 - a14*a21*a32),
d * (a21*a33*a42 + a22*a31*a43 + a23*a32*a41 - a21*a32*a43 - a22*a33*a41 - a23*a31*a42),
d * (a11*a32*a43 + a12*a33*a41 + a13*a31*a42 - a11*a33*a42 - a12*a31*a43 - a13*a32*a41),
d * (a11*a23*a42 + a12*a21*a43 + a13*a22*a41 - a11*a22*a43 - a12*a23*a41 - a13*a21*a42),
d * (a11*a22*a33 + a12*a23*a31 + a13*a21*a32 - a11*a23*a32 - a12*a21*a33 - a13*a22*a31)
};
return i;
}
Matrix4x4 Transpose() const;
@@ -126,6 +172,8 @@ namespace LinearAlgebra {
static Matrix4x4 FromTranslation(const Vector3& rhs);
static Matrix4x4 D3DOrthoProjLH(float nearPlane, float farPlane, float hViewportSize, float vViewportSize);
static Matrix4x4 D3DOrthoProjRH(float nearPlane, float farPlane, float hViewportSize, float vViewportSize);
static Matrix4x4 D3DPerspProjLH(float nearPlane, float farPlane, float hViewportSize, float vViewportSize);