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Adding extra sanity checks on all time dependant values to avoid bad behavior maybe

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This commit is contained in:
Sam Gateau 2018-09-13 23:48:50 -07:00
parent 568b5b9142
commit 1438643a5f
1 changed files with 26 additions and 11 deletions
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37
interface/src/LODManager.cpp
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@ -45,10 +45,11 @@ const float LOD_ADJUST_RUNNING_AVG_TIMESCALE = 0.08f; // sec
const float LOD_BATCH_TO_PRESENT_CUSHION_TIME = 3.0f; // msec
void LODManager::setRenderTimes(float presentTime, float engineRunTime, float batchTime, float gpuTime) {
_presentTime = presentTime;
_engineRunTime = engineRunTime;
_batchTime = batchTime;
_gpuTime = gpuTime;
// Make sure the sampled time are positive values
_presentTime = std::max(0.f, presentTime);
_engineRunTime = std::max(0.f, engineRunTime);
_batchTime = std::max(0.f, batchTime);
_gpuTime = std::max(0.f, gpuTime);
}
void LODManager::autoAdjustLOD(float realTimeDelta) {
@ -64,16 +65,29 @@ void LODManager::autoAdjustLOD(float realTimeDelta) {
auto presentTime = (_presentTime > _batchTime + LOD_BATCH_TO_PRESENT_CUSHION_TIME ? _batchTime + LOD_BATCH_TO_PRESENT_CUSHION_TIME : _presentTime);
float maxRenderTime = glm::max(glm::max(presentTime, _engineRunTime), _gpuTime);
// compute time-weighted running average maxRenderTime
// Note: we MUST clamp the blend to 1.0 for stability
float nowBlend = (realTimeDelta < LOD_ADJUST_RUNNING_AVG_TIMESCALE) ? realTimeDelta / LOD_ADJUST_RUNNING_AVG_TIMESCALE : 1.0f;
_nowRenderTime = (1.0f - nowBlend) * _nowRenderTime + nowBlend * maxRenderTime; // msec
// maxRenderTime must be a realistic valid duration in order for the regulation to work correctly.
// We make sure it s a non zero positive value (1.0ms) under 1 sec
maxRenderTime = std::max(1.0f, std::min(maxRenderTime, (float)MSECS_PER_SECOND));
// realTimeDelta must be a realistic valid duration in order for the regulation to work correctly.
// We make sure it a positive value under 1 sec
// note that if real time delta is very small we will early exit to avoid division by zero
realTimeDelta = std::max(0.0f, std::min(realTimeDelta, 1.0f));
// compute time-weighted running average render time (now and smooth)
// We MUST clamp the blend between 0.0 and 1.0 for stability
float nowBlend = (realTimeDelta < LOD_ADJUST_RUNNING_AVG_TIMESCALE) ? realTimeDelta / LOD_ADJUST_RUNNING_AVG_TIMESCALE : 1.0f;
float smoothBlend = (realTimeDelta < LOD_ADJUST_RUNNING_AVG_TIMESCALE * _smoothScale) ? realTimeDelta / (LOD_ADJUST_RUNNING_AVG_TIMESCALE * _smoothScale) : 1.0f;
_nowRenderTime = (1.0f - nowBlend) * _nowRenderTime + nowBlend * maxRenderTime; // msec
_smoothRenderTime = (1.0f - smoothBlend) * _smoothRenderTime + smoothBlend * maxRenderTime; // msec
if (!_automaticLODAdjust || _nowRenderTime == 0.0f || _smoothRenderTime == 0.0f) {
// early exit
// We must sanity check for the output average evaluated to be in a valid range to avoid issues
_nowRenderTime = std::max(0.0f, std::min(_nowRenderTime, (float)MSECS_PER_SECOND));
_smoothRenderTime = std::max(0.0f, std::min(_smoothRenderTime, (float)MSECS_PER_SECOND));
// Early exit if not regulating or if the render time doesn't matter
if (!_automaticLODAdjust || realTimeDelta == 0.f || _nowRenderTime == 0.0f || _smoothRenderTime == 0.0f) {
return;
}
@ -130,7 +144,8 @@ void LODManager::autoAdjustLOD(float realTimeDelta) {
glm::clamp(integral, -1.0f, 1.0f);
// Compute derivative
auto derivative = (error - previous_error) / dt;
// if dt is never zero becasuerrealTImeDelta would have early exit above, but if it was let's zero the derivative term
auto derivative = (dt <= 0.f ? 0.0f : (error - previous_error) / dt);
// remember history
_pidHistory.x = error;