Difference between revisions of "LlGetSunDirection"
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This script may have some inaccuracy to it. For more information see the Deep Notes below.
Tomos Halsey (talk | contribs) |
m (<lsl> and <cpp> tags to <source>) |
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|examples=This can be used to quickly determine whether it is day or night (in shortened SL days) as the script runs: if the returned vector's Z element is positive, then the sun is above the horizon. | |examples=This can be used to quickly determine whether it is day or night (in shortened SL days) as the script runs: if the returned vector's Z element is positive, then the sun is above the horizon. | ||
< | <source lang="lsl2">integer lightsOn = -1;//not TRUE or FALSE | ||
CheckSun() | CheckSun() | ||
| Line 21: | Line 21: | ||
llSetPrimitiveParams([ PRIM_FULLBRIGHT, ALL_SIDES, lightsOn ]); | llSetPrimitiveParams([ PRIM_FULLBRIGHT, ALL_SIDES, lightsOn ]); | ||
} | } | ||
}</ | }</source> | ||
This is a simple script to detect if its day or not. | This is a simple script to detect if its day or not. | ||
< | <source lang="lsl2"> | ||
//Added by To-mos Codewarrior(tomos.halsey) | //Added by To-mos Codewarrior(tomos.halsey) | ||
default | default | ||
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llSetPrimitiveParams([ PRIM_FULLBRIGHT, ALL_SIDES, !day]); | llSetPrimitiveParams([ PRIM_FULLBRIGHT, ALL_SIDES, !day]); | ||
} | } | ||
}</ | }</source> | ||
This script may have some inaccuracy to it. For more information see the Deep Notes below. | This script may have some inaccuracy to it. For more information see the Deep Notes below. | ||
|helpers | |helpers | ||
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</pre> | </pre> | ||
This is how mSunOffset is calculated: | This is how mSunOffset is calculated: | ||
<cpp>F64 daily_phase = DAILY_OMEGA * U64_to_F64(local_time / USEC_PER_SEC); | <source lang="cpp">F64 daily_phase = DAILY_OMEGA * U64_to_F64(local_time / USEC_PER_SEC); | ||
F32 sun_phase = (F32)fmod(daily_phase, 2.0*F_PI); | F32 sun_phase = (F32)fmod(daily_phase, 2.0*F_PI); | ||
sun_hour -= 6.0f; | sun_hour -= 6.0f; | ||
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// W *= 1 / |R| | // W *= 1 / |R| | ||
ang_velocityp *= 1.0f / R; | ang_velocityp *= 1.0f / R; | ||
}</ | }</source> | ||
Source: [https://lists.secondlife.com/pipermail/secondlifescripters/2007-July/001288.html Zyzzy Zarf] | Source: [https://lists.secondlife.com/pipermail/secondlifescripters/2007-July/001288.html Zyzzy Zarf] | ||
|permission | |permission | ||
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|cat5 | |cat5 | ||
|cat6 | |cat6 | ||
}}<div style="display:none;">< | }}<div style="display:none;"><source lang="lsl2"></source></div> | ||
Revision as of 02:59, 22 January 2015
| LSL Portal | Functions | Events | Types | Operators | Constants | Flow Control | Script Library | Categorized Library | Tutorials |
Summary
Function: vector llGetSunDirection( );| 177 | Function ID |
| 0.0 | Forced Delay |
| 10.0 | Energy |
Returns a vector that is a normalized vector of the direction of the sun in the region.
The sun position can be dynamic or static depending upon the wishes of the sim owner.
Caveats
Important Issues
~ All Issues ~ Search JIRA for related Bugs
|
|
VWR-3717 | A | llGetSunDirection not accurate |
Examples
This can be used to quickly determine whether it is day or night (in shortened SL days) as the script runs: if the returned vector's Z element is positive, then the sun is above the horizon.
integer lightsOn = -1;//not TRUE or FALSE
CheckSun()
{
vector sun = llGetSunDirection();
integer turnLightsOn = (sun.z < 0);
if(turnLightsOn != lightsOn)
{
lightsOn = turnLightsOn;
llSetPrimitiveParams([ PRIM_FULLBRIGHT, ALL_SIDES, lightsOn ]);
}
}
This is a simple script to detect if its day or not.
//Added by To-mos Codewarrior(tomos.halsey)
default
{
state_entry()
{llSetTimerEvent(1.0);}
timer()
{
vector sun=llGetSunDirection();
integer day=llRound(sun.z);
llSetText("Sun Pos: "+(string)sun+"Day: "+(string)day,<1.0,1.0,1.0>,1.0);
llSetPrimitiveParams([ PRIM_FULLBRIGHT, ALL_SIDES, !day]);
}
}
Notes
AVERAGE_SUN_TILT = -.25 * pi SEASONAL_SUN_TILT = .03 * pi SUN_NORMALIZED_OFFSET = .45
This is how mSunOffset is calculated:
F64 daily_phase = DAILY_OMEGA * U64_to_F64(local_time / USEC_PER_SEC);
F32 sun_phase = (F32)fmod(daily_phase, 2.0*F_PI);
sun_hour -= 6.0f;
mSunOffset = HOURS_TO_RADIANS * sun_hour - (0.25f * F_PI) * cosf(HOURS_TO_RADIANS * sun_hour) - sun_phase;
//And here's how sun direction is calculated:
void LLRegion::calculateSunInfo(
U64 current_time,
LLVector3& directionp,
LLVector3& ang_velocityp,
F32& sun_phase)
{
U64 local_time = current_time;
if(getSunFixed())
{
local_time = 0;
}
// Sun moves (once a day) about a circle that lies on a tilted plane.
// The angle of the plane cycles (once a year) a few radians about
// some average.
// These are F64's, otherwise we get rounding errors over time
F64 daily_phase = DAILY_OMEGA * U64_to_F64(local_time / USEC_PER_SEC) + mSunOffset;
F64 yearly_phase = YEARLY_OMEGA * U64_to_F64(local_time / USEC_PER_SEC);
F32 tilt = AVERAGE_SUN_TILT + SEASONAL_SUN_TILT_AMPLITUDE * (F32)sin(yearly_phase);
sun_phase = (F32)fmod(daily_phase, 2.0*F_PI);
// move sun around a circle
directionp.setVec((F32)cos(-daily_phase), (F32)sin(-daily_phase), 0.0f);
//tilt the circle about X-axis (due east)
directionp.rotVec(tilt, 1.0f, 0.0f, 0.0f);
// calculate angular velocity (radians per second)
ang_velocityp.setVec(0.0f, 0.0f, (F32)DAILY_OMEGA);
ang_velocityp.rotVec((F32)tilt, 1.0f, 0.0f, 0.0f);
// James wanted the night to be shorter than the day.
// We can do this by offsetting the center of the sun's orbit in the positive
// z-direction and normalizing the new vector.
directionp.mV[VZ] += SUN_NORMALIZED_OFFSET;
F32 R = directionp.normVec();
// We also need to correct the angular velocity
//
// V = W % R
// V has constant magnitude
// As R goes up, W must go down
// W and R are always perpendicular
// ===>
// W *= 1 / |R|
ang_velocityp *= 1.0f / R;
}
Source: Zyzzy Zarf
See Also
Functions
| • | llGetTimeOfDay |
Deep Notes
All Issues
~ Search JIRA for related Issues|
|
|
VWR-3717 | A | llGetSunDirection not accurate |
Tests
| • | Visual illustration | – | How good is this function? |
Signature |
|---|
function vector llGetSunDirection(); |