rename ZM -> IM

batch.go

@@ -30,7 +30,7 @@ var _ BasicTarget = (*Batch)(nil)
 func NewBatch(container Triangles, pic Picture) *Batch {
 	return &Batch{
 		cont: Drawer{Triangles: container, Picture: pic},
-		mat:  ZM,
+		mat:  IM,
 		col:  NRGBA{1, 1, 1, 1},
 	}
 }

geometry.go

@@ -230,8 +230,8 @@ func (r Rect) Contains(u Vec) bool {
 // vertically and then rotates everything by 90 degrees around the origin.
 type Matrix [9]float64
 
-// ZM stands for Zero-Matrix which is the identity matrix. Does nothing, no transformation.
-var ZM = Matrix(mgl64.Ident3())
+// IM stands for Zero-Matrix which is the identity matrix. Does nothing, no transformation.
+var IM = Matrix(mgl64.Ident3())
 
 // Move moves everything by the delta vector.
 func (m Matrix) Move(delta Vec) Matrix {

graphics.go

@@ -109,7 +109,7 @@ func NewIMDraw(pic Picture) *IMDraw {
 		d:   Drawer{Triangles: tri, Picture: pic},
 	}
 	im.Precision(64)
-	im.SetMatrix(ZM)
+	im.SetMatrix(IM)
 	im.SetColorMask(NRGBA{1, 1, 1, 1})
 	return im
 }