static void
playerUpdateVelocity(cpBody *body, cpVect gravity, cpFloat damping, cpFloat dt)
{
int jumpState = (ChipmunkDemoKeyboard.y > 0.0f);
// Grab the grounding normal from last frame
cpVect groundNormal = cpvzero;
cpBodyEachArbiter(playerBody, (cpBodyArbiterIteratorFunc)SelectPlayerGroundNormal, &groundNormal);
grounded = (groundNormal.y > 0.0);
if(groundNormal.y < 0.0f) remainingBoost = 0.0f;
// Do a normal-ish update
cpBool boost = (jumpState && remainingBoost > 0.0f);
cpVect g = (boost ? cpvzero : gravity);
cpBodyUpdateVelocity(body, g, damping, dt);
// Target horizontal speed for air/ground control
cpFloat target_vx = PLAYER_VELOCITY*ChipmunkDemoKeyboard.x;
// Update the surface velocity and friction
// Note that the "feet" move in the opposite direction of the player.
cpVect surface_v = cpv(-target_vx, 0.0);
playerShape->surfaceV = surface_v;
playerShape->u = (grounded ? PLAYER_GROUND_ACCEL/GRAVITY : 0.0);
// Apply air control if not grounded
if(!grounded){
// Smoothly accelerate the velocity
playerBody->v.x = cpflerpconst(playerBody->v.x, target_vx, PLAYER_AIR_ACCEL*dt);
}
body->v.y = cpfclamp(body->v.y, -FALL_VELOCITY, INFINITY);
}
static VALUE
rb_cpflerpconst(VALUE self, VALUE f1, VALUE f2, VALUE d) {
cpFloat result = cpflerpconst(NUM2DBL(f1), NUM2DBL(f2), NUM2DBL(d));
return rb_float_new(result);
}
