surf-pathfinder

this is an experimental, work-in-progress project that will eventually calculate perfect routes along surf ramps, adjusting dynamically to game conditions and player actions, for usage in TAS creation and as a guiding line for surfers.

features

• brachistochrone curve optimization for determining the fastest path along surf ramps
• real-time path adjustment based on changing game conditions and player actions
• efficient collision detection using the Gilbert-Johnson-Keerthi (GJK) algorithm and bounding volume hierarchy (BVH)
• accurate numerical methods for solving ordinary differential equations (ODEs) and integration
• advanced optimization strategies, including conjugate gradient and BFGS methods, with line search techniques
• pathfinding algorithms like A* for efficient deviation checking and path recalibration
• utilization of SIMD instructions and GPU acceleration for high-performance mathematical computations
• caching mechanisms for frequently used data and calculations
• thread-safe synchronization using mutexes for accessing shared data structures

surf_ramp entities

SurfRampOptimizer::OnEntityCreated function is called whenever a new entity is created. it checks if the entity's classname is "surf_ramp" and performs the necessary initialization and optimization steps.

when an entity with the classname "surf_ramp" is created:

1. a touch hook is set on the entity using pEntity->SetTouch(OnStartTouch), which allows detecting when a player touches the ramp
2. the GetRampFromEntity function is called to extract the ramp information from the entity, such as start point, end point, normal, length, width, and extents
3. a new instance of CBrachistochroneOptimizer is created with the extracted ramp information and added to the g_SurfRamps vector
4. the ramp is inserted into the collision detection system using CollisionDetection::InsertRamp(&ramp)

example surf_ramp entity:

classname "surf_ramp"  
startpoint "0 0 0"  
endpoint "100 0 0"  
normal "0 0 1"  
length "100"  
width "50"  

• startpoint: starting position of the ramp

• endpoint: the ending position of the ramp

• normal: the surface normal of the ramp

• length: the length of the ramp

• width: the width of the ramp

• minExtents: this vector represents the minimum x, y, and z coordinates that the ramp occupies in the 3D space. it defines the lower boundary or corner of the ramp's bounding volume

• maxExtents: same thing, but the opposite

extents are calculated from ramp properties and used for collision detection

TODO: implement functionality to search, view, edit ramp properties in g_SurfRamps as natives

TODO: implement functionality to easily create and destroy surf_ramp entities as natives

optimization process

the optimization process for a surf ramp and player follows these steps:

1. when a player touches a surf ramp entity, the CBrachistochroneOptimizer class is instantiated with the ramp and player information
2. the Optimize function is called to determine the fastest path along the ramp (brachistochrone curve optimization)
3. the optimized path is stored in the m_OptimizedPath member variable of the CBrachistochroneOptimizer instance
4. the Update function is called periodically to adjust the path in real-time based on changing game conditions and player actions
5. if the player deviates significantly from the optimized path, the RecalibratePath function of the PlayerMovementTracking class is called to find a new path using the A* algorithm.

TODO: implement visualization with tempents or something in sourcepawn

TODO: implement functionality to search, view and edit the optimized path data for a specific player and ramp as natives

handling ramp collisions:

1. uses the GJK algorithm and bounding volume hierarchy (BVH) for collision detection
2. automatically handles collisions between players and surf_ramp entities

TODO: perform additional collision checks and handle custom collision scenarios utilizing the collision detection functions provided in the CollisionDetection namespace

optimization parameters

• MAX_PLAYER_DIST_TO_PATH: max distance a player can deviate from the optimized path before triggering a recalibration
• OPTIMIZATION_METHOD: optimization method to use
• GRADIENT_TOLERANCE: tolerance threshold for the gradient descent optimization
• MAX_OPTIMIZATION_ITERATIONS: maximum number of iterations for the optimization process
• COLLISION_DETECTION_RESOLUTION: resolution of the collision detection grid

TODO: dynamically adjusting optimization parameters based on server performance and different game states

general todo

• integration with more advanced physics engines or libraries for even more accurate simulations and predictions
• utilization of machine learning techniques to adapt and improve the optimization process based on historical data and patterns
• create natives and forwards for sourcemod api
• create sourcepawn visualisation frontend
• expansion of the extension to support additional game modes, mechanics, or environments beyond surf ramps
• implementation of dynamic variables and config files (current implementation has many hardcoded magic numbers for debugging)
• memory cleanup and error handling
• better documentation and commenting
• further profiling and optimization for potentially expensive computations (currently utilizes SIMD instructions and GPU acceleration for performance and scalability)
• parallel processing to perform CPU intensive complex calculations, such as path optimization or physics simulations with multiple cores
• implement extensive logging

surf_ramp_optimizer.h

classes

• SurfRampOptimizer: main extension class that handles initialization, entity creation/destruction, and overall management of the optimization process.
• CBrachistochroneOptimizer: handles the brachistochrone curve optimization for a specific surf ramp and player.
• PlayerMovementTracking: tracks player movements and states, and recalibrates the path when deviations occur.
• BVHNode: represents a node in the bounding volume hierarchy used for efficient collision detection.
• Matrix: utility class for matrix operations.
• Vector: utility class for vector operations.
• Ramp: represents a surf ramp entity with properties like start point, end point, normal, length, width, and extents.

namespaces:

• CollisionDetection: contains functions for collision detection, including the GJK algorithm and intersection tests.
• NumericalMethods: provides numerical methods for solving ODEs, integration, and gradient calculations.
• MathUtils: contains utility functions for mathematical operations, including SIMD-optimized vector operations.
• Optimization: implements optimization algorithms and strategies, such as conjugate gradient, BFGS, and line search techniques.
• Pathfinding: contains the A* pathfinding algorithm for efficient path recalibration.

surf_ramp_optimizer.cpp

SurfRampOptimizer

• SurfRampOptimizer::SDK_OnLoad: initializes game interfaces and configurations.
• SurfRampOptimizer::SDK_OnUnload: cleans up resources and removes entity listeners.
• SurfRampOptimizer::SDK_OnAllLoaded: initializes collision detection and logs the server tickrate.
• SurfRampOptimizer::OnEntityCreated: handles the creation of new surf ramp entities and initializes optimization.
• SurfRampOptimizer::OnEntityDestroyed: handles the destruction of surf ramp entities and cleans up resources.
• SurfRampOptimizer::OnStartTouch: handles the event when a player touches a surf ramp and triggers optimization.

CBrachistochroneOptimizer

• CBrachistochroneOptimizer::Optimize: determines the fastest path along the ramp using brachistochrone curve optimization.
• CBrachistochroneOptimizer::Update: adjusts the path in real-time based on changing game conditions and player actions.
• CBrachistochroneOptimizer::PerformFlyCollisionResolution: resolves collisions during the optimization process.
• CBrachistochroneOptimizer::IsPathValid: checks if a given point is valid on the path.

PlayerMovementTracking

• PlayerMovementTracking::UpdatePlayerState: updates the player's state with position, velocity, and acceleration.
• PlayerMovementTracking::EstimatePlayerPosition: estimates the player's position based on the current state.
• PlayerMovementTracking::HasDeviatedFromPath: checks if the player has deviated significantly from the optimized path.
• PlayerMovementTracking::RecalibratePath: recalibrates the path using the A* algorithm if the player deviates.

BVHNode

• BVHNode::Insert: inserts a ramp into the bounding volume hierarchy.
• BVHNode::Query: queries the bounding volume hierarchy for ramps intersecting a given point.

CollisionDetection

• CollisionDetection::Initialize: initializes the collision detection system.
• CollisionDetection::Shutdown: shuts down the collision detection system.
• CollisionDetection::InsertRamp: inserts a ramp into the collision detection system.
• CollisionDetection::Intersects: checks if a point intersects with a ramp using the GJK algorithm.
• CollisionDetection::GJKIntersection: performs the GJK intersection test between two ramps.
• CollisionDetection::SupportPoint: finds the support point in a given direction for the GJK algorithm.
• CollisionDetection::FarthestPointInDirection: finds the farthest point in a given direction on a ramp.
• CollisionDetection::UpdateSimplex: updates the simplex for the GJK algorithm.

NumericalMethods

• NumericalMethods::SolveBrachistochrone: solves the brachistochrone problem using adaptive methods.
• NumericalMethods::CalculateBrachistochronePathTime: calculates the time required for the brachistochrone path.
• NumericalMethods::CalculateGradient: calculates the gradient for optimization.
• NumericalMethods::GaussianQuadrature: performs Gaussian quadrature for numerical integration.
• NumericalMethods::DormandPrince54: solves ODEs using the Dormand-Prince method.

MathUtils

• MathUtils::SIMDCrossProduct: calculates the cross product using SIMD instructions.
• MathUtils::SIMDDotProduct: calculates the dot product using SIMD instructions.
• MathUtils::SIMDLength: calculates the length of a vector using SIMD instructions.
• MathUtils::SIMDNormalized: normalizes a vector using SIMD instructions.
• MathUtils::ClipVelocity: clips the velocity vector based on a collision normal.

Optimization

• Optimization::OptimizePath: optimizes the path using the BFGS method.
• Optimization::OptimizePathConjugateGradient: optimizea the path using the conjugate gradient method.
• Optimization::OptimizePathBFGS: optimizes the path using the BFGS method.
• Optimization::SatisfiesWolfeConditions: checks if the Wolfe conditions are satisfied for line search.
• Optimization::LineSearch: performs line search for optimization.
• Optimization::CalculatePathCost: calculates the cost of a path.
• Optimization::GetClosestPointOnRamp: finds the closest point on a ramp.
• Optimization::UpdateInverseHessian: updates the inverse Hessian matrix for BFGS optimization.

Pathfinding

• Pathfinding::Pathfinding: implements the A* pathfinding algorithm for efficient path recalibration.

Misc

• GetRampFromEntity: extracts ramp information from a given entity.