package doodads import ( "git.kirsle.net/apps/doodle/render" ) // Doodad is a reusable drawing component used in Doodle. Doodads are buttons, // doors, switches, the player characters themselves, anything that isn't a part // of the level geometry. type Doodad interface { ID() string // Position and velocity, not saved to disk. Position() render.Point Velocity() render.Point Size() render.Rect // Movement commands. MoveBy(render.Point) // Add {X,Y} to current Position. MoveTo(render.Point) // Set current Position to {X,Y}. // Implement the Draw function. Draw(render.Engine) } // Collide describes how a collision occurred. type Collide struct { X int32 Y int32 W int32 H int32 Top bool Left bool Right bool Bottom bool } // CollidesWithGrid checks if a Doodad collides with level geometry. func CollidesWithGrid(d Doodad, grid *render.Grid) (Collide, bool) { var ( P = d.Position() S = d.Size() topLeft = P topRight = render.Point{ X: P.X + S.W, Y: P.Y, } bottomLeft = render.Point{ X: P.X, Y: P.Y + S.H, } bottomRight = render.Point{ X: bottomLeft.X + S.W, Y: P.Y + S.H, } ) // Bottom edge. for point := range render.IterLine2(bottomLeft, bottomRight) { if grid.Exists(render.Pixel{ X: point.X, Y: point.Y, }) { return Collide{ Bottom: true, X: point.X, Y: point.Y, }, true } } // Top edge. for point := range render.IterLine2(topLeft, topRight) { if grid.Exists(render.Pixel{ X: point.X, Y: point.Y, }) { return Collide{ Top: true, X: point.X, Y: point.Y, }, true } } for point := range render.IterLine2(topLeft, bottomLeft) { if grid.Exists(render.Pixel{ X: point.X, Y: point.Y, }) { return Collide{ Left: true, X: point.X, Y: point.Y, }, true } } for point := range render.IterLine2(topRight, bottomRight) { if grid.Exists(render.Pixel{ X: point.X, Y: point.Y, }) { return Collide{ Right: true, X: point.X, Y: point.Y, }, true } } return Collide{}, false }