fixes:

- using 1 func for grid collision checking with func arguments in
  player and obstacle systems.
- moving obstacles now kill player if business ends points toward him
  on contact
- added retry in popup menu

grid/collider.go

@@ -5,25 +5,30 @@ import (
 	. "openquell/config"
 )
 
-// FIXME: make available everywhere
+// Check a collision  on the grid. We check if  the entity in question
+// bumps into the  egde of the grid  or if it bumps onto  a solid wall
+// tile. For both cases the user must provide responder funcs in which
+// it must be implemented how to react on those events.
 func (grid *Grid) CheckGridCollision(
-	playerposition *components.Position,
-	velocity *components.Velocity) {
+	position *components.Position,
+	velocity *components.Velocity,
+	respond_edge func(*components.Position, *components.Velocity, *components.Position),
+	respond_solid func(*components.Position, *components.Velocity, *components.Position),
+) {
 
 	if velocity.Moving() {
-		ok, newpos := grid.BumpEdge(playerposition, velocity)
+		ok, newpos := grid.BumpEdge(position, velocity)
 		if ok {
 			//slog.Debug("falling off the edge", "newpos", newpos)
-			playerposition.Set(newpos)
+			respond_edge(position, velocity, newpos)
 		} else {
-			ok, tilepos := grid.GetSolidNeighborPosition(playerposition, velocity, true)
+			ok, tilepos := grid.GetSolidNeighborPosition(position, velocity, true)
 			if ok {
 				// slog.Debug("HaveSolidNeighbor", "ok", ok, "tilepos",
 				// 	tilepos.Point(), "playerpos", playerposition)
-				intersects, newpos := tilepos.Intersects(playerposition, velocity)
+				intersects, newpos := tilepos.Intersects(position, velocity)
 				if intersects {
-					playerposition.Set(newpos)
-					velocity.Change(Stop)
+					respond_solid(position, velocity, newpos)
 				}
 			}
 		}