From 8d2db7eeeec3b684939d563db22bef2036f3c53d Mon Sep 17 00:00:00 2001
From: Nicolas Nattis <nicolas.nattis@gmail.com>
Date: Fri, 2 Oct 2020 14:34:32 -0300
Subject: [PATCH] Improves code

---
 code/__HELPERS/matrices.dm                    | 52 +++++++++++--------
 .../camera/camera_image_capturing.dm          | 25 ++++-----
 2 files changed, 44 insertions(+), 33 deletions(-)

diff --git a/code/__HELPERS/matrices.dm b/code/__HELPERS/matrices.dm
index 0cb19e9c0f4..3623c09d43b 100644
--- a/code/__HELPERS/matrices.dm
+++ b/code/__HELPERS/matrices.dm
@@ -1,3 +1,34 @@
+/// Datum which stores information about a matrix decomposed with decompose().
+/datum/decompose_matrix
+	///?
+	var/scale_x = 1
+	///?
+	var/scale_y = 1
+	///?
+	var/rotation = 0
+	///?
+	var/shift_x = 0
+	///?
+	var/shift_y = 0
+
+/// Decomposes a matrix into scale, shift and rotation.
+///
+/// If other operations were applied on the matrix, such as shearing, the result
+/// will not be precise.
+/matrix/proc/decompose()
+	var/datum/decompose_matrix/decompose_matrix = new
+	. = decompose_matrix
+	decompose_matrix.scale_x = sqrt(a * a + d * d)
+	decompose_matrix.scale_y = sqrt(b * b + e * e)
+	decompose_matrix.shift_x = c
+	decompose_matrix.shift_y = f
+	if(!decompose_matrix.scale_x || !decompose_matrix.scale_y)
+		return
+	// If only translated, scaled and rotated, a/xs == e/ys and -d/xs == b/xy
+	var/cossine = (a/decompose_matrix.scale_x + e/decompose_matrix.scale_y) / 2
+	var/sine = (b/decompose_matrix.scale_y - d/decompose_matrix.scale_x) / 2
+	decompose_matrix.rotation = arctan(cossine, sine)
+
 /matrix/proc/TurnTo(old_angle, new_angle)
 	. = new_angle - old_angle
 	Turn(.) //BYOND handles cases such as -270, 360, 540 etc. DOES NOT HANDLE 180 TURNS WELL, THEY TWEEN AND LOOK LIKE SHIT
@@ -55,27 +86,6 @@
 	. += f
 	. += 1
 
-///The X scale of the matrix
-/matrix/proc/get_x_scale()
-	return sqrt(a * a + d * d)
-
-///The Y scale of the matrix
-/matrix/proc/get_y_scale()
-	return sqrt(b * b + e * e)
-
-/// Gets the rotation of the matrix, in degrees.
-/// Will produce correct results if the matrix is only being translated, scaled
-/// and rotated. Otherwise this is a best attempt.
-/matrix/proc/get_rotation()
-	var/xs = get_x_scale()
-	var/ys = get_y_scale()
-	if(!xs || !ys)
-		return 0
-	// If only translated, scaled and rotated, a/xs == e/ys and -d/xs == b/xy
-	var/cossine = (a/xs + e/ys) / 2
-	var/sine = (b/ys - d/xs) / 2
-	return arctan(cossine, sine)
-
 ///The X pixel offset of this matrix
 /matrix/proc/get_x_shift()
 	. = c
diff --git a/code/modules/photography/camera/camera_image_capturing.dm b/code/modules/photography/camera/camera_image_capturing.dm
index 7f7caa0bfee..95966711a4f 100644
--- a/code/modules/photography/camera/camera_image_capturing.dm
+++ b/code/modules/photography/camera/camera_image_capturing.dm
@@ -85,20 +85,21 @@
 				// Center of the image in Y
 				var/yo = (clone.y - center.y) * world.icon_size + clone.pixel_y + ycomp + clone.step_y
 
-				if(clone.transform) // getFlatIcon doesn't give a snot about transforms.'
-					var/sx = clone.transform.get_x_scale()
-					var/sy = clone.transform.get_y_scale()
-					if(sx != 1 || sy != 1)
+				if(clone.transform) // getFlatIcon doesn't give a snot about transforms.
+					var/datum/decompose_matrix/decompose = clone.transform.decompose()
+					// Scale in X, Y
+					if(decompose.scale_x != 1 || decompose.scale_y != 1)
 						var/base_w = img.Width()
 						var/base_h = img.Height()
-						img.Scale(base_w * sx, base_h * sy)
-						xo -= base_w * (sx - 1) / 2
-						yo -= base_h * (sy - 1) / 2
-					var/rx = clone.transform.get_rotation()
-					if(rx != 0)
-						img.Turn(rx)
-					xo += clone.transform.get_x_shift()
-					yo += clone.transform.get_x_shift()
+						img.Scale(base_w * decompose.scale_x, base_h * decompose.scale_y)
+						xo -= base_w * (decompose.scale_x - 1) / 2
+						yo -= base_h * (decompose.scale_y - 1) / 2
+					// Rotation
+					if(decompose.rotation != 0)
+						img.Turn(decompose.rotation)
+					// Shift
+					xo += decompose.shift_x
+					yo += decompose.shift_y
 
 				res.Blend(img, blendMode2iconMode(clone.blend_mode), xo, yo)
 			CHECK_TICK