From 1317cd12d74dba4ff765d6e18b0b30cdf42002a3 Mon Sep 17 00:00:00 2001
From: Lars Müller <34514239+appgurueu@users.noreply.github.com>
Date: Tue, 20 Sep 2022 10:55:51 +0200
Subject: Fix formula used for acceleration (#12353)

---
 src/client/localplayer.cpp | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

(limited to 'src/client/localplayer.cpp')

diff --git a/src/client/localplayer.cpp b/src/client/localplayer.cpp
index 14be3321b..f9caf9e8b 100644
--- a/src/client/localplayer.cpp
+++ b/src/client/localplayer.cpp
@@ -292,7 +292,7 @@ void LocalPlayer::move(f32 dtime, Environment *env, f32 pos_max_d,
 	float player_stepheight = (m_cao == nullptr) ? 0.0f :
 		(touching_ground ? m_cao->getStepHeight() : (0.2f * BS));
 
-	v3f accel_f;
+	v3f accel_f(0, -gravity, 0);
 	const v3f initial_position = position;
 	const v3f initial_speed = m_speed;
 
@@ -778,6 +778,9 @@ void LocalPlayer::old_move(f32 dtime, Environment *env, f32 pos_max_d,
 	m_speed += m_added_velocity;
 	m_added_velocity = v3f(0.0f);
 
+	// Apply gravity (note: this is broken, but kept since this is *old* move code)
+	m_speed.Y -= gravity * dtime;
+
 	/*
 		Collision detection
 	*/
@@ -1117,8 +1120,10 @@ void LocalPlayer::handleAutojump(f32 dtime, Environment *env,
 		}
 	}
 
-	float jump_height = 1.1f; // TODO: better than a magic number
-	v3f jump_pos = initial_position + v3f(0.0f, jump_height * BS, 0.0f);
+	float jumpspeed = movement_speed_jump * physics_override.jump;
+	float peak_dtime = jumpspeed / gravity; // at the peak of the jump v = gt <=> t = v / g
+	float jump_height = (jumpspeed - 0.5f * gravity * peak_dtime) * peak_dtime; // s = vt - 1/2 gt^2
+	v3f jump_pos = initial_position + v3f(0.0f, jump_height, 0.0f);
 	v3f jump_speed = initial_speed;
 
 	// try at peak of jump, zero step height
-- 
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