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Planet: Fix gravity and centrifugal force for planet_keep_scale 

Gravity / centrifugal force calculation didn't take into account that
the heights on a planet that preserves the aspect ratio of nodes is
actually different from just the y-coordinate, since the shader applies
the exponential function. The centrifugal force now also takes the width
of blocks into account (real speed = blocks per second * block width),
so that the force near the planet center and further up is now more
realistic.
master
Jeija 2016-09-09 15:30:20 +02:00
parent 655f6f69a7
commit 493c6bc371
1 changed files with 10 additions and 2 deletions
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12
src/environment.cpp
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@ -2479,20 +2479,28 @@ void ClientEnvironment::step(float dtime)
float gravity_coeff = 1;
float planet_radius = g_settings->getU16("planet_radius") * MAP_BLOCKSIZE * BS;
float height = planet_radius + lplayer->getPosition().Y;
// When stretching out the planet so that blocks keep their aspect ratio,
// the height will actually be the magnitude of the complex exponential function
if (g_settings->getBool("planet_keep_scale"))
height = planet_radius * exp(lplayer->getPosition().Y / planet_radius);
float blockwidth = height / planet_radius;
if (g_settings->getBool("planet_enable") && g_settings->getBool("planet_realistic_gravity")) {
if (lplayer->getPosition().Y < 0)
gravity_coeff = height / planet_radius;
else
gravity_coeff = (planet_radius * planet_radius) / (height * height);
}
if(lplayer->in_liquid == false)
speed.Y -= gravity_coeff * lplayer->movement_gravity * lplayer->physics_override_gravity * dtime_part * 2;
// Planet: Apply centrifugal force
// a_z = v^2 / height with v = (horizontal speed) * (block width at that height)
if (g_settings->getBool("planet_enable") && g_settings->getBool("planet_centrifugal_enable") && lplayer->in_liquid == false)
speed.Y += (speed.X * speed.X + speed.Z * speed.Z) /
(g_settings->getU16("planet_radius") * MAP_BLOCKSIZE * BS + lplayer->getPosition().Y) * dtime_part * 2;
speed.Y += (speed.X * speed.X + speed.Z * speed.Z) * blockwidth * blockwidth / height * dtime_part * 2;
// Liquid floating / sinking
if(lplayer->in_liquid && !lplayer->swimming_vertical)