From 1e19db5b25bbff71728a9fc283acf3775a23c4be Mon Sep 17 00:00:00 2001
From: Jacek Olszak <jacekolszak@gmail.com>
Date: Tue, 12 Feb 2019 18:40:15 +0100
Subject: [PATCH] #159 Add test case when matrix determinant is not 1
---
geometry.go | 4 ++--
geometry_test.go | 6 ++++++
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/geometry.go b/geometry.go
index 621a0b4..e847b52 100644
--- a/geometry.go
+++ b/geometry.go
@@ -405,7 +405,7 @@ func (m Matrix) Project(u Vec) Vec {
func (m Matrix) Unproject(u Vec) Vec {
det := m[0]*m[3] - m[2]*m[1]
return Vec{
- m[3]/det*u.X - m[2]/det*u.Y + m[2]*m[5] - m[3]*m[4],
- -m[1]/det*u.X + m[0]/det*u.Y + m[1]*m[4] - m[0]*m[5],
+ m[3]/det*u.X - m[2]/det*u.Y + (m[2]*m[5]-m[3]*m[4])/det,
+ -m[1]/det*u.X + m[0]/det*u.Y + (m[1]*m[4]-m[0]*m[5])/det,
}
}
diff --git a/geometry_test.go b/geometry_test.go
index b1ce00f..17b184f 100644
--- a/geometry_test.go
+++ b/geometry_test.go
@@ -100,6 +100,12 @@ func TestMatrix_Unproject(t *testing.T) {
assert.InDelta(t, unprojected.X, 2, delta)
assert.InDelta(t, unprojected.Y, 2, delta)
})
+ t.Run("for scaled, rotated and moved matrix", func(t *testing.T) {
+ matrix := pixel.IM.Scaled(pixel.ZV, 2).Rotated(pixel.ZV, math.Pi/2).Moved(pixel.V(2, 2))
+ unprojected := matrix.Unproject(pixel.V(-2, 6))
+ assert.InDelta(t, unprojected.X, 2, delta)
+ assert.InDelta(t, unprojected.Y, 2, delta)
+ })
t.Run("for rotated and moved matrix", func(t *testing.T) {
matrix := pixel.IM.Rotated(pixel.ZV, math.Pi/2).Moved(pixel.V(1, 1))
unprojected := matrix.Unproject(pixel.V(1, 2))
--
GitLab