fix teleporting

animationMario.go

@@ -84,6 +84,18 @@ func (a *Animation) updateMarioPosition() {
 	minCenterY := halfH
 	maxCenterY := a.ctx.Height() - 1 - halfH
 
+	// If the sprite is larger than the panel in a dimension, collapse
+	// the allowed center range to the panel center so we don't get
+	// immediate collisions every frame which makes Mario flash.
+	if maxCenterX < minCenterX {
+		minCenterX = centerX
+		maxCenterX = centerX
+	}
+	if maxCenterY < minCenterY {
+		minCenterY = centerY
+		maxCenterY = centerY
+	}
+
 	// parametric angle before any reflection
 	t := a.mario.angle
 
@@ -95,6 +107,16 @@ func (a *Animation) updateMarioPosition() {
 	collidedX := marioX < minCenterX || marioX > maxCenterX
 	collidedY := marioY < minCenterY || marioY > maxCenterY
 
+	// If allowed range collapsed to the center, don't reflect on that axis
+	// because reflection would keep flipping every frame. Treat that as
+	// non-colliding for reflection purposes (we'll clamp position later).
+	if minCenterX == maxCenterX {
+		collidedX = false
+	}
+	if minCenterY == maxCenterY {
+		collidedY = false
+	}
+
 	// Reflect the parametric angle correctly:
 	// - For horizontal collision we want cos(t_new) = -cos(t) => t_new = Pi - t
 	// - For vertical collision we want sin(t_new) = -sin(t)   => t_new = -t