updated

programs/roulette.lua

@@ -66,17 +66,21 @@ local COL_BALL     = 0xF0F0F0
 local COL_BALL_SHD = 0x444444
 
 -- Ball physics
-local BALL_RADIUS      = 8      -- px
-local BALL_SPEED_MIN   = 420    -- px/s  initial tangential speed
-local BALL_SPEED_MAX   = 620
-local TRACK_RESTITUTION = 0.72  -- speed fraction kept on track-wall bounce
-local POCKET_RESTITUTION = 0.45 -- speed fraction kept bouncing inside pocket ring
-local FRICTION_TRACK   = 0.992  -- multiplier per frame while in track (energy loss)
-local FRICTION_POCKET  = 0.970  -- higher damping once in pocket ring
--- Ball enters pocket ring when its speed drops below this
-local DROP_SPEED       = 90     -- px/s
+local BALL_RADIUS       = 8       -- px
+local BALL_SPEED_MIN    = 900     -- px/s  initial tangential speed
+local BALL_SPEED_MAX    = 1300
+local TRACK_RESTITUTION  = 0.82   -- speed fraction kept on track-wall bounce
+local POCKET_RESTITUTION = 0.52   -- speed fraction kept bouncing inside pocket ring
+local FRICTION_TRACK    = 0.9985  -- multiplier per frame while in track
+local FRICTION_POCKET   = 0.972   -- higher damping once in pocket ring
+-- Centripetal slide: inward acceleration applied as ball slows, simulating
+-- the ball losing grip and sliding down the slope toward the centre.
+local SLIDE_ACCEL       = 380     -- px/s² inward pull (scales with 1/speed)
+local SLIDE_THRESHOLD   = 500     -- px/s  below this speed the slide kicks in
+-- Ball enters pocket ring when speed drops below this
+local DROP_SPEED        = 80      -- px/s
 -- Small random kick angle on each wall bounce
-local BOUNCE_KICK_MAX  = 0.12   -- rad
+local BOUNCE_KICK_MAX   = 0.10    -- rad
 
 ----------------------------------------------------------------------
 -- GPU / pixel primitives
@@ -315,6 +319,23 @@ local function spin()
         vx = vx * fric
         vy = vy * fric
 
+        -- Centripetal slide: as the ball slows it loses centripetal support
+        -- and slides inward, like a real ball on a tilted cone/bowl.
+        if not inPocket and speed < SLIDE_THRESHOLD and speed > DROP_SPEED then
+            local dx0  = bx - CX
+            local dy0  = by - CY
+            local d0   = math.sqrt(dx0*dx0 + dy0*dy0)
+            if d0 > 0 then
+                -- Inward unit vector
+                local inx = -dx0 / d0
+                local iny = -dy0 / d0
+                -- Acceleration scales up as speed decreases
+                local accel = SLIDE_ACCEL * (1 - speed / SLIDE_THRESHOLD)
+                vx = vx + inx * accel * dt
+                vy = vy + iny * accel * dt
+            end
+        end
+
         -- Integrate
         bx = bx + vx * dt
         by = by + vy * dt