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added missing rotation of normals #14

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Merged
Jannik-Hm merged 2 commits into from
Nov 26, 2025
Merged

added missing rotation of normals #14

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3264d0a
added missing rotation of normals
Jannik-Hm Nov 26, 2025
ebefce2
fixed rotate and translate unit test
Jannik-Hm Nov 26, 2025
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7 changes: 7 additions & 0 deletions pkg/MeshTypes/matrix.go
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Original file line number Diff line number Diff line change
Expand Up @@ -43,3 +43,10 @@ func (a Matrix) MulPosition(b Vector) Vector {
z := a.X20*b.X + a.X21*b.Y + a.X22*b.Z + a.X23
return Vector{x, y, z}
}

func (a Matrix) MulDirection(b Vector) Vector {
x := a.X00*b.X + a.X01*b.Y + a.X02*b.Z
y := a.X10*b.X + a.X11*b.Y + a.X12*b.Z
z := a.X20*b.X + a.X21*b.Y + a.X22*b.Z
return Vector{x, y, z}.Normalize()
}
12 changes: 12 additions & 0 deletions pkg/MeshTypes/mesh.go
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Expand Up @@ -31,6 +31,18 @@ func (obj *Mesh) RotateAndTranslate(translationMatrix Matrix) {
triangle.V0.Position = translationMatrix.MulPosition(triangle.V0.Position)
triangle.V1.Position = translationMatrix.MulPosition(triangle.V1.Position)
triangle.V2.Position = translationMatrix.MulPosition(triangle.V2.Position)
if triangle.V0.Normal != nil {
n0 := translationMatrix.MulDirection(*triangle.V0.Normal)
triangle.V0.Normal = &n0
}
if triangle.V1.Normal != nil {
n1 := translationMatrix.MulDirection(*triangle.V1.Normal)
triangle.V1.Normal = &n1
}
if triangle.V2.Normal != nil {
n2 := translationMatrix.MulDirection(*triangle.V2.Normal)
triangle.V2.Normal = &n2
}
}
}

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12 changes: 12 additions & 0 deletions tests/MeshTypes/mesh_test.go
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Expand Up @@ -85,6 +85,18 @@ func TestRotateAndTranslate(t *testing.T) {
triangle.V0.Position = translationMatrix.MulPosition(triangle.V0.Position) // safe to use as func is tested in another place
triangle.V1.Position = translationMatrix.MulPosition(triangle.V1.Position)
triangle.V2.Position = translationMatrix.MulPosition(triangle.V2.Position)
if triangle.V0.Normal != nil {
n0 := translationMatrix.MulDirection(*triangle.V0.Normal)
triangle.V0.Normal = &n0
}
if triangle.V1.Normal != nil {
n1 := translationMatrix.MulDirection(*triangle.V1.Normal)
triangle.V1.Normal = &n1
}
if triangle.V2.Normal != nil {
n2 := translationMatrix.MulDirection(*triangle.V2.Normal)
triangle.V2.Normal = &n2
}
}
if !reflect.DeepEqual(result, want) {
t.Errorf("Mesh RotateAndTranslate() Output does not match expected")
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