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include/Spectre/Math/Transform.h: Adding inverse()

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This commit is contained in:
Henrik Hautakoski 2023-08-04 17:32:07 +02:00
parent d8db86e40c
commit 0f7a4bbabc
2 changed files with 22 additions and 0 deletions
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4
include/Spectre/Math/Transform.h
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@ -53,6 +53,10 @@ public :
Transform& scale(Vector2f offset);
Transform& scale(float s);
// Inverse
Transform inverse();
Transform& combine(const Transform& other);
Vector2f transformPoint(float x, float y) const;

18
source/Math/Transform.cpp
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@ -1,5 +1,6 @@
#include <Spectre/Math/Math.h>
#include <Spectre/Math/Matrix3.h>
#include <Spectre/Math/Transform.h>
namespace sp {
@ -83,6 +84,23 @@ Transform& Transform::scale(float s)
return scale(s, s);
}
Transform Transform::inverse()
{
// Because a 2D Transform matrix is really just a 3x3 matrix.
// We can cheat here :)
Matrix3f m(m_matrix.e[0], m_matrix.e[1], m_matrix.e[3],
m_matrix.e[4], m_matrix.e[5], m_matrix.e[7],
m_matrix.e[12], m_matrix.e[13], m_matrix.e[15]);
m = m.inverse();
return Transform(
m.v[0], m.v[3], m.v[6],
m.v[1], m.v[4], m.v[7],
m.v[2], m.v[5], m.v[8]
);
}
Transform& Transform::combine(const Transform& other)
{
m_matrix *= other.m_matrix;