From b39e6566b9bc453b2c53ce136c12b44b370d387b Mon Sep 17 00:00:00 2001
From: terencehill <piuntn@gmail.com>
Date: Sat, 16 Mar 2024 02:52:31 +0100
Subject: [PATCH] Revert "Don't allow negative values for the y component of
 the shot origin offset because the gun can't be aligned to the left by
 default. Thanks to this change it's possible to restore precision of the y
 and z components back to 0.25"

because player weapon alignment (cl_gunalign) is applied before compression, thus the y component can be negative.

This reverts commit 490abae3d36ba1d00c0884adc56e5f4905bab439. It fixes #2896
---
 qcsrc/common/util.qc | 50 ++++++++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/qcsrc/common/util.qc b/qcsrc/common/util.qc
index d9a098691..b9e951149 100644
--- a/qcsrc/common/util.qc
+++ b/qcsrc/common/util.qc
@@ -1184,44 +1184,43 @@ vector get_shotvelocity(vector myvel, vector mydir, float spd, float newton_styl
 	return myvel + spd * mydir;
 }
 
-/*
- * Compresses the shot origin offset vector to an int with the following format:
- * xxxxxxxx|Syyyyyyy|Syzzzzzz
- * 32109876|54321098|76543210
- * 1st byte: x component
- * 2nd byte: y component in the last 7 bits and the sign of the x component in the 1st bit
- * 3rd byte: z component in the last 7 bits and the sign of the z component in the 1st bit
- * All values are multiplied on compression and divided on decompression
- * so the precision of the values is 0.5 if multiplied by 2 and 0.25 if multiplied by 4
- * Values are bound to the following ranges:
- * x: -127.5  +127.5
- * y:      0  +31.75 negative values not allowed because the gun can't be aligned to the left by default
- * z: -31.75  +31.75
- */
+// compresses the shot origin offset vector to an int with the following format:
+// xxxxxxxx SSyyyyyy SUzzzzzz
+// 32109876 54321098 76543210
+// 1st byte: x component (it uses all 8 bits)
+// 2nd byte: y component in the last 6 bits and the signs of the x and y components
+// 3rd byte: z component in the last 6 bits and the sign of the z component (the 2nd bit is unused)
+// all values are doubled on compression and halved on decompression
+// so the precision for all components is 0.5
+// values are bound to the following ranges:
+// x: -127.5 +127.5
+// y:  -31.5  +31.5
+// z:  -31.5  +31.5
 float compressShotOrigin(vector v)
 {
 	int rx_neg = (v.x < 0) ? 1 : 0;
+	int ry_neg = (v.y < 0) ? 1 : 0;
 	int rz_neg = (v.z < 0) ? 1 : 0;
 	int rx = rint(fabs(v.x) * 2);
-	int ry = rint(v.y * 4);
-	int rz = rint(fabs(v.z) * 4);
-	if(rx > 255) // 128 * 2 - 1
+	int ry = rint(fabs(v.y) * 2);
+	int rz = rint(fabs(v.z) * 2);
+	if(rx > 255)
 	{
 		LOG_DEBUG("shot origin ", vtos(v), " x out of bounds\n");
 		rx = bound(0, rx, 255);
 	}
-	if(ry > 127 || ry < 0) // 32 * 4 - 1
+	if(ry > 63)
 	{
 		LOG_DEBUG("shot origin ", vtos(v), " y out of bounds\n");
-		ry = bound(0, ry, 127);
+		ry = bound(0, ry, 63);
 	}
-	if(rz > 127) // 32 * 4 - 1
+	if(rz > 63)
 	{
 		LOG_DEBUG("shot origin ", vtos(v), " z out of bounds\n");
-		rz = bound(0, rz, 127);
+		rz = bound(0, rz, 63);
 	}
-	ry |= rx_neg * BIT(7);
-	rz |= rz_neg * BIT(7);
+	ry |= ry_neg * BIT(6) + rx_neg * BIT(7);
+	rz |= rz_neg * BIT(6); // BIT(7) unused
 	return rx * 0x10000 + ry * 0x100 + rz;
 }
 vector decompressShotOrigin(int f)
@@ -1232,8 +1231,9 @@ vector decompressShotOrigin(int f)
 	v.z = f & 0xFF;
 	// remove sign bits and apply sign
 	if (v.y & BIT(7)) { v.y &= ~BIT(7); v.x *= -1; }
-	if (v.z & BIT(7)) { v.z &= ~BIT(7); v.z *= -1; }
-	return vec3(v.x / 2, v.y / 4, v.z / 4);
+	if (v.y & BIT(6)) { v.y &= ~BIT(6); v.y *= -1; }
+	if (v.z & BIT(6)) { v.z &= ~BIT(6); v.z *= -1; }
+	return v / 2;
 }
 
 #ifdef GAMEQC
-- 
2.39.2