joint_solver.h

#pragma once
 
#include <cstdint>
#include <vector>
 
#include <glm/glm.hpp>
 
#include "system/physics/solver/solver.h"
#include "system/physics/solver/solver_math.h"
 
namespace Vkm::Engine {

struct JointConstraint {
    uint32_t bodyA = 0;
    uint32_t bodyB = 0;
 
    glm::vec3 anchorA = {0.0f, 0.0f, 0.0f};  
    glm::vec3 anchorB = {0.0f, 0.0f, 0.0f};  

    float distance = -1.0f;
 
    float stiffness = 1.0f;

    bool      solvable = false;               
    glm::mat3 mass     = glm::mat3(0.0f);     
    glm::vec3 bias     = {0.0f, 0.0f, 0.0f};  

    glm::vec3 impulse = {0.0f, 0.0f, 0.0f};
 
    float     holdTorque   = 0.0f;                    
    glm::quat heldRotation = {1.0f, 0.0f, 0.0f, 0.0f};  
    float     holdLimit    = 0.0f;                    
 
    bool      holdSolvable = false;               
    glm::mat3 holdMass     = glm::mat3(0.0f);     
    glm::vec3 holdBias     = {0.0f, 0.0f, 0.0f};  
    glm::vec3 holdImpulse  = {0.0f, 0.0f, 0.0f};  
};

struct JointSprings {
    SolverMath::SoftConstraint anchor;
    SolverMath::SoftConstraint hold;
};

JointSprings prepareJoints(
    const std::vector<PhysicsBody>& bodies,
    std::vector<JointConstraint>& joints,
    float dt
);

void warmStartJoints(std::vector<PhysicsBody>& bodies, const std::vector<JointConstraint>& joints);

void solveJointPass(
    std::vector<PhysicsBody>& bodies,
    std::vector<JointConstraint>& joints,
    const JointSprings& springs,
    bool useBias
);
 
} // namespace Vkm::Engine