Optimizing Game Performance Across Devices And Platforms
Understanding Game Performance Limitations
Game performance is often constrained by hardware capabilities such as the central processing unit (CPU), graphics processing unit (GPU), and memory. The CPU processes game logic, physics, artificial intelligence, and more. The GPU renders graphics and visual effects. Speed and capacity of memory impacts asset streaming and workload. Identifying performance bottlenecks across these components is key.
During rendering, many factors influence achieved frames per second. The number of draw calls to render models, environments, effects, and user interfaces can create overhead. Complex fragment and vertex shaders that run for each screen pixel also decrease FPS. Likewise, advanced post-processing, shadows, and lighting effects add to GPU workload. These bottlenecks must be addressed to prevent frame rate drops.
Game physics and collision detection add computational work for the CPU each frame. Complex AI behavior trees for many simultaneous enemies can also constrain performance without optimization. Managing draw calls, simplifying shaders, optimizing physics and AI engines is required.
Optimizing Graphics and Assets
Several established techniques exist to optimize graphics workloads. Object batching batches together draw calls for many low-polygon models into single calls, reducing overhead. Texture atlasing combines many small textures into larger ones, accessing them via sprite coordinates. Both batching and atlasing improve rendering performance.
Efficient 3D model design is also key. Low-polygon models with edge collapse, texture baking, normal/displacement mapping impart detail while being less expensive to render. Level of detail (LOD) models switch between model versions of different complexities based on distance. This also improves FPS during gameplay.
High-resolution textures increase memory usage and sampling work per-pixel. Compression formats like ETC, PVRTC, ASTC reduce memory requirements and bandwidth while decoding fast on GPU. Audio files at high sample/bit rates also must be compressed via OGG, MP3 etc to conserve memory.
Writing Efficient Game Code
Beyond graphics, much game logic code executes each frame driving (p>gameplay, physics, AI etc. This code must utilize efficient algorithms and data structures to prevent wasted computation. Profiling tools help identify problem code sections needing optimization.
Pathfinding for enemy AI can leverage A* or navigation meshes over slower breadth-first search. Spatial partitioning via BSP trees, octrees, grids speeds up collision, culling, lighting passes. Object pools minimize memory allocations during effects and gameplay events. Data oriented design organizes data for cache efficiency.
Expensive routines can sometimes be multi-threaded across CPU cores for concurrent execution. This includes physics, animation, batch processing. Task granularity and synchronization overhead must be managed to see gains.
Adapting to Target Devices
Games release on vastly different platforms from PC, mobile, console with varying capabilities. Adaptively scaling graphical quality and interface/mechanics design is needed for quality experiences.
Device capability detection allows determining GPU, CPU performance, screen resolution at runtime. Scalable graphics settings disable expensive effects like shadows, anti-aliasing, bloom on slower hardware. Lower polygon models, texture resolution better suit bandwidth constrained platforms.
Interface elements must adapt to smaller touchscreens requiring larger buttons without precision inputs. Mobile game design revolves around shorter play sessions with progression retained via cloud save games. Detecting gamepads allows remapping controls from touch input.
Testing and Benchmarking
Verifying performance on target devices using profiling tools catches problems early. Frametime graphs visualize FPS stability over play sessions, indicating spikes needing investigation via platform GPU/CPU profilers available on PC, Playstation, Xbox etc.
Critical gameplay systems like input response, AI updates define minimum performance thresholds. Stress testing battles with maximum entities establishes acceptable degrade. Memory leak detection ensures stability for long playtimes. Testing at multiple specification Points catches hardware specific issues.
Achieving Consistent Frame Rates
Smooth, consistent frame rates enhance immersion during gameplay. Adaptively reducing rendering resolution or visual detail counters transient workload spikes from complex scenes. Capping frame rate just below device refresh rate via vertical sync avoids wasted frames and tearing artifacts.
For 60FPS target, optimizing systems to fit rendering and game logic code within a 16ms frame budget minimizes variability. Compromising visual fidelity maintains this target frame time. Managing level of detail, draw calls, effects based on prior frames achieves stable frame rates.
