physics-related fixes

src/objects/Player.cpp

@@ -35,9 +35,10 @@ Player::~Player() {
 }
 
 void Player::updateInput(
-        Level* level,
-        PlayerInput& input, 
-        float delta) {
+    Level* level,
+    PlayerInput& input, 
+    float delta
+) {
     bool crouch = input.shift && hitbox->grounded && !input.sprint;
     float speed = this->speed;
     if (flight){
@@ -76,9 +77,9 @@ void Player::updateInput(
         hitbox->velocity.z += dir.z * speed * delta * 9;
     }
 
-    float vel = std::max(glm::length(hitbox->velocity * 0.25f), 1.0f);
-    int substeps = int(delta * vel * 1000);
-    substeps = std::min(100, std::max(1, substeps));
+    float vel = glm::length(hitbox->velocity);
+    int substeps = int(delta * vel * 20);
+    substeps = std::min(100, std::max(2, substeps));
     level->physics->step(
         level->chunks.get(), 
         hitbox.get(), 

src/physics/PhysicsSolver.cpp

@@ -21,16 +21,17 @@ void PhysicsSolver::step(
     float gravityScale,
     bool collisions
 ) {
-    float dt = delta / float(substeps);
+    float dt = delta / static_cast<float>(substeps);
     float linear_damping = hitbox->linear_damping;
     float s = 2.0f/BLOCK_AABB_GRID;
+
+    const glm::vec3& half = hitbox->halfsize;
+    glm::vec3& pos = hitbox->position;
+    glm::vec3& vel = hitbox->velocity;
     
     bool prevGrounded = hitbox->grounded;
     hitbox->grounded = false;
     for (uint i = 0; i < substeps; i++) {
-        glm::vec3& pos = hitbox->position;
-        glm::vec3& half = hitbox->halfsize;
-        glm::vec3& vel = hitbox->velocity;
         float px = pos.x;
         float pz = pos.z;
         
@@ -41,7 +42,8 @@ void PhysicsSolver::step(
         }
         vel.x *= glm::max(0.0f, 1.0f - dt * linear_damping);
         vel.z *= glm::max(0.0f, 1.0f - dt * linear_damping);
-        pos += vel * dt;
+
+        pos += vel * dt + gravity * gravityScale * dt * dt * 0.5f;
 
         if (shifting && hitbox->grounded){
             float y = (pos.y-half.y-E);