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fine tuning the noise coef ramp and documenting the algorithm

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Sam Gateau 2018-08-30 12:11:43 -07:00
parent 6c502e79e3
commit 78c7948ebc
1 changed files with 19 additions and 4 deletions
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23
interface/src/LODManager.cpp
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@ -100,8 +100,12 @@ void LODManager::autoAdjustLOD(float realTimeDelta) {
float currentFPS = (float)MSECS_PER_SECOND / _avgRenderTime;
float currentSmoothFPS = (float)MSECS_PER_SECOND / _smoothRenderTime;
// Compute the Variance of the FPS signal (FPS - smouthFPS)^2
// Also scale it by a percentage for fine tuning (default is 100%)
float currentVarianceFPS = (currentSmoothFPS - currentFPS);
currentVarianceFPS *= currentVarianceFPS;
currentVarianceFPS *= _pidCoefs.w;
auto dt = realTimeDelta;
@ -114,11 +118,22 @@ void LODManager::autoAdjustLOD(float realTimeDelta) {
auto errorSquare = smoothError * smoothError;
auto noiseCoef = (errorSquare < _pidCoefs.w * currentVarianceFPS ? 0.0f : 1.0f);
// Define a noiseCoef that is trying to adjust the error to the FPS target value based on its strength
// relative to the current Variance of the FPS signal.
// If the error is within the variance, just set to 0.
// if its within 2x the variance scale the control
// and full control if error is bigger than 2x variance
auto noiseCoef = 1.0f;
if (errorSquare < currentVarianceFPS) {
noiseCoef = 0.0f;
} else if (errorSquare < 2.0f * currentVarianceFPS) {
noiseCoef = (errorSquare - currentVarianceFPS) / currentVarianceFPS;
}
auto normalizedError = noiseCoef * smoothError / targetFPS;
auto error = glm::clamp(normalizedError, -1.0f, 1.0f);
// The final normalized error is the the error to the FPS target, weighted by the noiseCoef, then normailzed by the target FPS.
// it s also clamped in the [-1, 1] range
auto error = noiseCoef * smoothError / targetFPS;
error = glm::clamp(error, -1.0f, 1.0f);
auto integral = previous_integral + error * dt;
glm::clamp(integral, -1.0f, 1.0f);