Editing Games Featuring Advanced Physics (section)

=A Comprehensive Overview=
Physics engines are the backbone of classic titles, responsible for simulating the real-world behavior of objects. They provide the foundation for realistic interactions between characters, environments, and objects within a virtual world. Advanced calculations such as choosing kinetic energy based approach and momentum based approach depending on case and need, inelastic collisions and bounciness etc. further contributes to realism.

;Core Physics Concepts
*     Rigid body dynamics: This involves simulating objects as rigid bodies with mass, shape, and velocity. Gravity, rotation, and collision detection are fundamental aspects of rigid body physics.
*     Soft body dynamics: For more deformable objects like cloth or flesh, soft body physics is employed. It accounts for elasticity, plasticity, and tearing. This one is crucial for [https://www.youtube.com/@RandomMadnessChannel/videos gore elements].
*     Fluid dynamics: This branch of physics simulates the behavior of liquids and gases, crucial for games with water, smoke, or fire effects.
*     Aero physics: For flight simulations or games with aerial combat, aero physics models the interaction between objects and air, including lift, drag, and thrust.
*     Particle physics: This involves simulating the behavior of individual particles, often used for creating effects like sparks, explosions, or rain.

;Advanced Physics Features
*     Ragdolls: These are physics-driven character models that simulate realistic physical behavior when injured or killed.
*     Inverse kinematics: This technique allows for natural-looking motion by calculating joint positions based on desired end-effector positions (e.g., hands or feet).
*     Collision detection: Accurate collision detection ensures that objects interact realistically, preventing penetration and clipping.
*     Weight simulation: This feature allows for realistic weight distribution and balance in characters and objects.
*     Destruction physics: This enables objects to break apart realistically under stress or impact.
*     Responsive volumetric smoke: [[#List|Counter-Strike 2]]’s smoke technology, uses a voxel grid to simulate dynamic, interactive smoke that fills spaces naturally, reacts to lighting, and allows bullets or explosions to carve paths through it, enhancing tactical gameplay. This way, results could even more impressive than Mafia II smoke physics when Nvidia PhysX turned on, or [https://youtu.be/zsjmLNZtvxk Batman Arkham Knight's interactive smoke & fog powered by Nvidia GameWorks].

;Integration with Other Game Systems  
*     Dynamic lighting and Self-shadowing: Physics-based interactions can influence lighting, such as shadows cast by moving objects or reflections on surfaces.
*     Dynamic sound effects: The sound of objects colliding, breaking, or moving can be generated dynamically based on physics interactions.
*     Dynamic weather systems: Physics can be used to simulate wind, rain, snow, and other weather effects, influencing gameplay and visuals.

By mastering these concepts and techniques, game developers can create immersive and believable virtual worlds that captivate players. To enhance visual fidelity and realism, games often incorporate a variety of animations, sound effects, 3D models and objects, including damage models. Interactive foliage such as touch bending vegetation or when a character is hit, the game dynamically switch to a damaged model, animation set and appropriate sound effects with visual effects like blood, bruises, or clothing damage. This level of detail examples can significantly enhance the player's immersion and sense of realism. While physics engines strive for realism, game developers often employ optimization techniques to ensure acceptable performance. One such example is the use of 'limited amount of active 3d models and objects on the screen simultaneously', which allow for only small number of objects to be present in the game world without overwhelming the physics engine. However, this can sometimes lead to trade-offs in realism, such as models that may lose their physics or disappear after a certain period of time to conserve resources. In some cases, game developers employ alternative solutions to reduce the workload, such as using "LOD technique". However there are techniques without sacrificing the huge chunk of performance such as Parallax occlusion mapping, but this kind of implementations needs dedication and resources. Especially in the early days of FPS games there are instances where developers implement workarounds due to technical limitations, such as player in first person viewpoint only see the arms and gun, with no visible body, players may even notice differences in character models between first-person and third-person perspectives or variations in models seen by different players in multiplayer games. 

==Physics Engine Integration in Game Loops==
;A typical game loop incorporates a physics engine in the following steps<ref>[https://old.reddit.com/r/gamedev/comments/1frppvv/comment/lpeo3rg/ Reddit Thread: How does a physics engine work with a rendering engine?]</ref>:
#     Begin Frame: This marks the start of a new frame.
#     Do Pre-Physics Gameplay Logic: Any game logic that needs to occur before physics simulation is executed here. This might include player input, AI updates, or other game-specific calculations.
#     Send Object Locations to Physics Engine: The current positions and orientations of all objects in the game world are sent to the physics engine.
#     Simulate Physics via the Physics Engine: The physics engine calculates new positions, velocities, and rotations for objects based on their current state, forces, and collisions.
#     Update to New Object Locations from Physics Engine: The game updates the positions and orientations of objects to match the results of the physics simulation.
#     Do Post-Physics Gameplay Logic: Any game logic that depends on the updated object positions is executed here. This might include character animations, object interactions, or particle effects.
#     Packaged/Send All Final Object Locations to the Renderer: The final positions and orientations of objects are prepared and sent to the rendering system.
#     Renderer Processes Objects: The renderer determines how each object should be drawn, considering factors like camera position, lighting, and materials.
#     Renderer Sends the Results to GPU: The renderer sends the rendering data to the GPU, which is responsible for actually drawing the graphics.
#     GPU Does What the Renderer Says and Produces the Final Image: The GPU processes the rendering data and generates the final image that is displayed on the screen.
#     Frame Ends: The current frame is complete, and the process repeats for the next frame.

==Physics Processing on Hardware==
See [[wikipedia:Physics processing unit]] page.

*NVIDIA removed support for 32-bit PhysX on 50-series GPU.[https://youtu.be/RsJKNAvaC1Y]
*There are also physics related software libraries released such as AMD GPUOpen (incl. [[wikipedia:TressFX|AMD TressFX]]), Nvidia GameWorks (incl. [https://www.nvidia.com/en-us/geforce/technologies/hairworks/ NVIDIA Hairworks]), but some of the components of these are kinda abandoned in favor of current offerings such as RTX.