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src/Viewer/sview.*: Added damping to chase views.

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This commit is contained in:
Julian Smith 2020-12-21 14:54:53 +00:00
parent cbe3ae5618
commit d9e535913e
2 changed files with 93 additions and 43 deletions
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132
src/Viewer/sview.cxx
View file

@ -141,6 +141,51 @@ struct SviewPosDir
};
/* Generic damping support. Improved version of class in view.hxx and view.cxx.
We model dx/dt = (target-current)/damping_time, do damping_time is time for
value to change by a factor or e. */
struct Damping {
/* If m_wrap_max is non-zero, we wrap to ensure values are always between 0
and m_wrap_max. E.g. use m_wrap_max=360 for an angle. */
Damping(double damping_time, double wrap_max=0, double current=0)
:
m_damping_time(damping_time),
m_current(current),
m_wrap_max(wrap_max)
{}
/* Updates and returns new smoothed value. */
double update(double dt, double target)
{
const double e = 2.718281828459045;
double delta = target - m_current;
if (m_wrap_max) {
if (delta < -m_wrap_max/2) delta += m_wrap_max;
if (delta >= m_wrap_max/2) delta -= m_wrap_max;
}
m_current = target - delta * pow(e, -dt/m_damping_time);
if (m_wrap_max) {
if (m_current < 0) m_current += m_wrap_max;
if (m_current >= m_wrap_max) m_current -= m_wrap_max;
}
return m_current;
}
/* Forces current value to be <current>. */
double reset(double current)
{
m_current = current;
return m_current;
}
private:
double m_damping_time;
double m_current;
double m_wrap_max;
};
/* Abstract base class for a single view step. A view step modifies a
SviewPosDir, e.g. translating the position and/or rotating the direction. */
struct SviewStep
@ -318,22 +363,32 @@ E.g. can be used to preserve direction (relative to aircraft) of Helicopter
view at the time it was cloned. */
struct SviewStepRotate : SviewStep
{
SviewStepRotate(double heading, double pitch, double roll, bool fixed=false)
SviewStepRotate(
double heading,
double pitch,
double roll,
bool fixed=false,
double damping_heading=0,
double damping_pitch=0,
double damping_roll=0
)
:
m_heading(heading),
m_pitch(pitch),
m_roll(roll),
m_fixed(fixed)
m_fixed(fixed),
m_damping_heading(damping_heading, 360 /*m_wrap_max*/),
m_damping_pitch(damping_pitch, 360 /*m_wrap_max*/),
m_damping_roll(damping_roll, 360 /*m_wrap_max*/)
{
SG_LOG(SG_VIEW, SG_INFO, "heading=" << heading << " pitch=" << pitch << " roll=" << roll);
}
void evaluate(SviewPosDir& posdir, double dt) override
{
/* Should we use SGQuatd to evaluate things? */
posdir.heading += m_heading;
posdir.pitch += m_pitch;
posdir.roll += m_roll;
posdir.heading = m_damping_heading.update(dt, posdir.heading + m_heading);
posdir.pitch = m_damping_pitch.update(dt, posdir.pitch + m_pitch);
posdir.roll = m_damping_roll.update(dt, posdir.roll + m_roll);
}
void mouse_drag(double delta_x, double delta_y) override
@ -364,6 +419,9 @@ struct SviewStepRotate : SviewStep
double m_pitch;
double m_roll;
bool m_fixed;
Damping m_damping_heading;
Damping m_damping_pitch;
Damping m_damping_roll;
};
/* Multiply heading, pitch and roll by constants. */
@ -592,34 +650,6 @@ struct SviewStepFinal : SviewStep
};
/* Generic damping support. Improved version of class in view.hxx and view.cxx.
We model dx/dt = (target-current)/damping_time, do damping_time is time for
value to change by a factor or e. */
struct Damping {
Damping(double damping_time, double current=0)
:
m_damping_time(damping_time),
m_current(current)
{}
double update(double target, double dt)
{
const double e = 2.718281828459045;
m_current = target - (target - m_current) * pow(e, -dt/m_damping_time);
return m_current;
}
double reset(double current)
{
m_current = current;
return m_current;
}
private:
double m_damping_time;
double m_current;
};
/* Change angle and field of view so that we can see an aircraft and the ground
immediately below it. */
struct SviewStepAGL : SviewStep
@ -690,7 +720,7 @@ struct SviewStepAGL : SviewStep
double relative_height_target_plus = relative_height_target + aircraft_size_vertical;
double relative_height_ground_ = relative_height_ground;
relative_height_ground = relative_height_ground_damping.update(relative_height_ground, dt);
relative_height_ground = relative_height_ground_damping.update(dt, relative_height_ground);
if (relative_height_ground > relative_height_target) {
/* Damping of relative_height_ground can result in it being
temporarily above the aircraft, so we ensure the aircraft is
@ -1075,6 +1105,14 @@ struct SviewView
static int s_id;
};
/* Converts legacy damping values (e.g. at-model-heading-damping) to a damping
time suitable for use by our Damping class. */
static double legacy_damping_time(double damping)
{
if (damping <= 0) return 0;
return 1 / damping;
}
int SviewView::s_id = 0;
/* A view defined by a series of steps that defines an eye and a target. Used
@ -1125,7 +1163,7 @@ struct SviewViewEyeTarget : SviewView
if (config->getBoolValue("view/config/lookat-agl")) {
double damping = config->getDoubleValue("view/config/lookat-agl-damping");
double damping_time = log(10) / damping;
double damping_time = log(10) * legacy_damping_time(damping);
SG_LOG(SG_VIEW, SG_ALERT, "lookat-agl");
m_steps.add_step(new SviewStepAGL(callsign, damping_time));
}
@ -1156,7 +1194,7 @@ struct SviewViewEyeTarget : SviewView
}
else {
SG_LOG(SG_VIEW, SG_INFO, "not eye-fixed");
/* E.g. Pilot view or Helicopter view. */
/* E.g. Pilot view and Helicopter/Chase views. */
SGPropertyNode* global_sim_view = globals->get_props()
->getNode("sim/view", config->getIntValue("view-number-raw"));
@ -1182,9 +1220,7 @@ struct SviewViewEyeTarget : SviewView
aircraft's heading, pitch and roll; this enables us to mimic
Helicopter and Chase views. In theory we should evaluate the
specified paths, but in practise we only need to multiply
current values by 0 or 1.
todo: add damping. */
current values by 0 or 1. */
assert(global_sim_view);
m_steps.add_step(new SviewStepDirectionMultiply(
global_sim_view->getStringValue("config/eye-heading-deg-path")[0] ? 1 : 0,
@ -1197,10 +1233,18 @@ struct SviewViewEyeTarget : SviewView
viewing system's Helicopter view etc, increments to
heading-offset-deg and pitch-offset-deg actually correspond
to a decreasing actual heading and pitch values. */
double damping_heading = legacy_damping_time(config->getDoubleValue("view/config/at-model-heading-damping"));
double damping_pitch = legacy_damping_time(config->getDoubleValue("view/config/at-model-pitch-damping"));
double damping_roll = legacy_damping_time(config->getDoubleValue("view/config/at-model-roll-damping"));
m_steps.add_step(new SviewStepRotate(
-globals->get_props()->getDoubleValue("sim/current-view/heading-offset-deg"),
-globals->get_props()->getDoubleValue("sim/current-view/pitch-offset-deg"),
globals->get_props()->getDoubleValue("sim/current-view/roll-offset-deg")
globals->get_props()->getDoubleValue("sim/current-view/roll-offset-deg"),
false /*fixed*/,
damping_heading,
damping_pitch,
damping_roll
));
/* Add step that moves eye away from aircraft.
@ -1208,14 +1252,16 @@ struct SviewViewEyeTarget : SviewView
fgdata:defaults.xml) which is -ve, e.g. -25m. */
m_steps.add_step(new SviewStepMove(
config->getDoubleValue("view/config/z-offset-m"),
config->getDoubleValue("view/config/y-offset-m"),
-config->getDoubleValue("view/config/y-offset-m"),
config->getDoubleValue("view/config/x-offset-m")
));
m_steps.add_step(new SviewStepFinalToTarget);
/* Finally add a step that converts
lat,lon,height,heading,pitch,roll into SGVec3d position and
SGQuatd orientation. */
m_steps.add_step(new SviewStepFinal);
//m_steps.add_step(new SviewStepFinal);
}
else {
/* E.g. pilot view.

4
src/Viewer/sview.hxx
View file

@ -105,6 +105,10 @@ config:
pitch
roll
zoom-delta: modification to default zoom.
Chase view seems to be slightly different from the real legacy
view, possibly because the viewpoint correction config/y-offset-m
is applied after rotation instead of before.
"sview" or not specified:
List of sview-step's.