Exploring Game Loop Implementations for Optimal Performance

Introduction to Game Loops

In game development, the game loop is a critical component that dictates how the game processes updates and renders frames. Recently, I have developed two distinct versions of a game loop that are designed to function equivalently. The choice between these loops hinges on specific performance needs and rendering requirements.

Understanding the Code Structure

The following code snippet illustrates how I have structured my game loop:

cpp
#if (GAMELOOP == 1)
    mRoot->startRendering();
#else
    // Question: Does renderOneFrame() execute unconditionally or only if time permits?
    while (frameStarted(FrameEvent()) && mRoot->renderOneFrame() && frameEnded(FrameEvent()));
#endif

Here, GAMELOOP serves as a flag to determine which version of the loop will be executed. The frameEnded function is defined as follows:

cpp
time2 = GetTickCount();
Sleep(std::max((long)0, (long)(SIMSTEPTIME - time2 + time1)));

This may appear unconventional at first glance; however, it essentially calculates the remaining time needed for each frame based on SIMSTEPTIME, which is derived from dividing 1000 by FRAMESPERSECOND. Currently set at 100 frames per second, this value can be adjusted based on performance testing.

Consistency in Frame Rate

Theoretically speaking, maintaining a constant SIMSTEPTIME should yield similar visual results regardless of which looping method is employed—provided that the application can consistently meet its target frame rate. If not managed properly, variations in speed may occur during gameplay.

Both implementations seem to perform reliably thus far; however, I plan to conduct an objective automated test soon to gather more data on their efficiency.

Evaluating Rendering Methods

While I lean towards using my custom loop over startRendering(), documentation within the OGRE library suggests otherwise. It states that users are not obligated to utilize this automatic rendering mechanism since it primarily benefits high-frame-rate applications like games. For scenarios where continuous refreshes aren’t necessary—such as editor tools—it’s advisable to manually update render targets when required by invoking RenderTarget::update. Alternatively, developers can manage their own rendering cycles through calls to Root::renderOneFrame.

This insight contradicts my earlier beliefs about optimal practices in rendering loops.

Seeking Expert Opinions

Given these considerations and findings regarding high-performance gaming loops aimed at consistent speed management, I would greatly appreciate additional perspectives on which style might be most effective for achieving superior performance in gaming applications. Your insights would be invaluable as I refine my approach moving forward.