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#159 Add test case when matrix determinant is not 1

This commit is contained in:
Jacek Olszak 2019-02-12 18:40:15 +01:00
parent a0713598da
commit 1e19db5b25
2 changed files with 8 additions and 2 deletions
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4
geometry.go
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@ -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,
}
}

6
geometry_test.go
View File

@ -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))