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Andrew Meadows 2017-12-20 11:36:51 -08:00
parent 721e9d426a
commit c1906215ba
2 changed files with 22 additions and 8 deletions
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28
interface/src/LODManager.cpp
View file

@ -19,10 +19,6 @@
#include "LODManager.h"
const uint64_t LOD_AUTO_ADJUST_PERIOD = 500 * USECS_PER_MSEC;
const float LOD_AUTO_ADJUST_DECREMENT_FACTOR = 0.8f;
const float LOD_AUTO_ADJUST_INCREMENT_FACTOR = 1.2f;
Setting::Handle<float> desktopLODDecreaseFPS("desktopLODDecreaseFPS", DEFAULT_DESKTOP_LOD_DOWN_FPS);
Setting::Handle<float> hmdLODDecreaseFPS("hmdLODDecreaseFPS", DEFAULT_HMD_LOD_DOWN_FPS);
@ -44,10 +40,28 @@ float LODManager::getLODIncreaseFPS() {
return getDesktopLODIncreaseFPS();
}
void LODManager::autoAdjustLOD(float renderTime, float deltaTimeSec) {
// We use a "time-weighted running average" of the renderTime and compare it against min/max thresholds
// to determine if we should adjust the level of detail (LOD).
//
// A time-weighted running average has a timescale which determines how fast the average tracks the measured
// value in real-time. Given a step-function in the mesured value, and assuming measurements happen
// faster than the runningAverage is computed, the error between the value and its runningAverage will be
// reduced by 1/e every timescale of real-time that passes.
const float LOD_ADJUST_RUNNING_AVG_TIMESCALE = 0.1f; // sec
//
// Assuming the measured value is affected by logic invoked by the runningAverage bumping up against its
// thresholds, we expect the adjustment to introduce a step-function. We want the runningAverage settle
// to the new value BEFORE we test it aginst its thresholds again. Hence we test on a period that is a few
// multiples of the running average timescale:
const uint64_t LOD_AUTO_ADJUST_PERIOD = 5 * (uint64_t)(LOD_ADJUST_RUNNING_AVG_TIMESCALE * (float)USECS_PER_MSEC); // usec
const float LOD_AUTO_ADJUST_DECREMENT_FACTOR = 0.8f;
const float LOD_AUTO_ADJUST_INCREMENT_FACTOR = 1.2f;
void LODManager::autoAdjustLOD(float renderTime, float realTimeDelta) {
// compute time-weighted running average renderTime
const float LOD_ADJUST_TIMESCALE = 0.1f; // sec
float blend = (deltaTimeSec < LOD_ADJUST_TIMESCALE) ? deltaTimeSec / LOD_ADJUST_TIMESCALE : 1.0f;
// Note: we MUST clamp the blend to 1.0 for stability
float blend = (realTimeDelta < LOD_ADJUST_RUNNING_AVG_TIMESCALE) ? realTimeDelta / LOD_ADJUST_RUNNING_AVG_TIMESCALE : 1.0f;
_avgRenderTime = (1.0f - blend) * _avgRenderTime + blend * renderTime; // msec
if (!_automaticLODAdjust) {
// early exit

2
interface/src/LODManager.h
View file

@ -62,7 +62,7 @@ public:
Q_INVOKABLE float getLODIncreaseFPS();
static bool shouldRender(const RenderArgs* args, const AABox& bounds);
void autoAdjustLOD(float renderTime, float deltaTimeSec);
void autoAdjustLOD(float renderTime, float realTimeDelta);
void loadSettings();
void saveSettings();