diff --git a/examples/physics/chipmunk/main.go b/examples/physics/chipmunk/main.go index f477d99..85a629e 100644 --- a/examples/physics/chipmunk/main.go +++ b/examples/physics/chipmunk/main.go @@ -1,139 +1,163 @@ package main import ( + "fmt" "math" "math/rand" "github.com/gen2brain/raylib-go/raylib" - - "github.com/vova616/chipmunk" - "github.com/vova616/chipmunk/vect" + "github.com/jakecoffman/cp" ) -const ( - ballRadius = 25 - ballMass = 1 -) - -// Game type -type Game struct { - Space *chipmunk.Space - Balls []*chipmunk.Shape - StaticLines []*chipmunk.Shape - - ticksToNextBall int +var grabbableMaskBit uint = 1 << 31 +var grabFilter = cp.ShapeFilter{ + cp.NO_GROUP, grabbableMaskBit, grabbableMaskBit, } -// NewGame - Start new game -func NewGame() (g Game) { - g.Init() - return +func randUnitCircle() cp.Vector { + v := cp.Vector{X: rand.Float64()*2.0 - 1.0, Y: rand.Float64()*2.0 - 1.0} + if v.LengthSq() < 1.0 { + return v + } + return randUnitCircle() } -// Init - Initialize game -func (g *Game) Init() { - g.createBodies() - - g.ticksToNextBall = 10 +var simpleTerrainVerts = []cp.Vector{ + {350.00, 425.07}, {336.00, 436.55}, {272.00, 435.39}, {258.00, 427.63}, {225.28, 420.00}, {202.82, 396.00}, + {191.81, 388.00}, {189.00, 381.89}, {173.00, 380.39}, {162.59, 368.00}, {150.47, 319.00}, {128.00, 311.55}, + {119.14, 286.00}, {126.84, 263.00}, {120.56, 227.00}, {141.14, 178.00}, {137.52, 162.00}, {146.51, 142.00}, + {156.23, 136.00}, {158.00, 118.27}, {170.00, 100.77}, {208.43, 84.00}, {224.00, 69.65}, {249.30, 68.00}, + {257.00, 54.77}, {363.00, 45.94}, {374.15, 54.00}, {386.00, 69.60}, {413.00, 70.73}, {456.00, 84.89}, + {468.09, 99.00}, {467.09, 123.00}, {464.92, 135.00}, {469.00, 141.03}, {497.00, 148.67}, {513.85, 180.00}, + {509.56, 223.00}, {523.51, 247.00}, {523.00, 277.00}, {497.79, 311.00}, {478.67, 348.00}, {467.90, 360.00}, + {456.76, 382.00}, {432.95, 389.00}, {417.00, 411.32}, {373.00, 433.19}, {361.00, 430.02}, {350.00, 425.07}, } -// Update - Update game -func (g *Game) Update() { - g.ticksToNextBall-- - if g.ticksToNextBall == 0 { - g.ticksToNextBall = rand.Intn(100) + 1 - g.addBall() +// creates a circle with random placement +func addCircle(space *cp.Space, radius float64) { + mass := radius * radius / 25.0 + body := space.AddBody(cp.NewBody(mass, cp.MomentForCircle(mass, 0, radius, cp.Vector{}))) + body.SetPosition(randUnitCircle().Mult(180)) + + shape := space.AddShape(cp.NewCircle(body, radius, cp.Vector{})) + shape.SetElasticity(0) + shape.SetFriction(0.9) +} + +// creates a simple terrain to contain bodies +func simpleTerrain() *cp.Space { + space := cp.NewSpace() + space.Iterations = 10 + space.SetGravity(cp.Vector{0, -100}) + space.SetCollisionSlop(0.5) + + offset := cp.Vector{X: -320, Y: -240} + for i := 0; i < len(simpleTerrainVerts)-1; i++ { + a := simpleTerrainVerts[i] + b := simpleTerrainVerts[i+1] + space.AddShape(cp.NewSegment(space.StaticBody, a.Add(offset), b.Add(offset), 0)) } - // Physics steps calculations - g.step(raylib.GetFrameTime()) -} - -// Draw - Draw game -func (g *Game) Draw() { - for i := range g.StaticLines { - x := g.StaticLines[i].GetAsSegment().A.X - y := g.StaticLines[i].GetAsSegment().A.Y - - x2 := g.StaticLines[i].GetAsSegment().B.X - y2 := g.StaticLines[i].GetAsSegment().B.Y - - raylib.DrawLine(int32(x), int32(y), int32(x2), int32(y2), raylib.DarkBlue) - } - - for _, b := range g.Balls { - pos := b.Body.Position() - raylib.DrawCircleLines(int32(pos.X), int32(pos.Y), float32(ballRadius), raylib.DarkBlue) - } -} - -// createBodies sets up the chipmunk space and static bodies -func (g *Game) createBodies() { - g.Space = chipmunk.NewSpace() - g.Space.Gravity = vect.Vect{0, 900} - - staticBody := chipmunk.NewBodyStatic() - g.StaticLines = []*chipmunk.Shape{ - chipmunk.NewSegment(vect.Vect{250.0, 240.0}, vect.Vect{550.0, 280.0}, 0), - chipmunk.NewSegment(vect.Vect{550.0, 280.0}, vect.Vect{550.0, 180.0}, 0), - } - - for _, segment := range g.StaticLines { - segment.SetElasticity(0.6) - staticBody.AddShape(segment) - } - - g.Space.AddBody(staticBody) -} - -// addBall adds ball to chipmunk space and body -func (g *Game) addBall() { - x := rand.Intn(600-200) + 200 - ball := chipmunk.NewCircle(vect.Vector_Zero, float32(ballRadius)) - ball.SetElasticity(0.95) - - body := chipmunk.NewBody(vect.Float(ballMass), ball.Moment(float32(ballMass))) - body.SetPosition(vect.Vect{vect.Float(x), 0.0}) - body.SetAngle(vect.Float(rand.Float32() * 2 * math.Pi)) - body.AddShape(ball) - - g.Space.AddBody(body) - g.Balls = append(g.Balls, ball) -} - -// step advances the physics engine and cleans up any balls that are off-screen -func (g *Game) step(dt float32) { - g.Space.Step(vect.Float(dt)) - - for i := 0; i < len(g.Balls); i++ { - p := g.Balls[i].Body.Position() - if p.Y < -100 { - g.Space.RemoveBody(g.Balls[i].Body) - g.Balls[i] = nil - g.Balls = append(g.Balls[:i], g.Balls[i+1:]...) - i-- // consider same index again - } - } + return space } func main() { - raylib.InitWindow(800, 450, "raylib [physics] example - chipmunk") + const width, height = 800, 450 + const physicsTickrate = 1.0 / 60.0 - raylib.SetTargetFPS(60) + raylib.SetConfigFlags(raylib.FlagVsyncHint) + raylib.InitWindow(width, height, "raylib [physics] example - chipmunk") - game := NewGame() + offset := raylib.Vector2{X: width / 2, Y: height / 2} + // since the example ported from elsewhere, flip the camera 180 and offset to center it + camera := raylib.NewCamera2D(offset, raylib.Vector2{}, 180, 1) + space := simpleTerrain() + for i := 0; i < 1000; i++ { + addCircle(space, 5) + } + mouseBody := cp.NewKinematicBody() + var mouse cp.Vector + var mouseJoint *cp.Constraint + + var accumulator, dt float32 + lastTime := raylib.GetTime() for !raylib.WindowShouldClose() { + // calculate dt + now := raylib.GetTime() + dt = now - lastTime + lastTime = now + + // update the mouse position + mousePos := raylib.GetMousePosition() + // alter the mouse coordinates based on the camera position, rotation + mouse.X = float64(mousePos.X-camera.Offset.X) * -1 + mouse.Y = float64(mousePos.Y-camera.Offset.Y) * -1 + // smooth mouse movements to new position + newPoint := mouseBody.Position().Lerp(mouse, 0.25) + mouseBody.SetVelocityVector(newPoint.Sub(mouseBody.Position()).Mult(60.0)) + mouseBody.SetPosition(newPoint) + + // handle grabbing + if raylib.IsMouseButtonPressed(raylib.MouseLeftButton) { + result := space.PointQueryNearest(mouse, 5, grabFilter) + if result.Shape != nil && result.Shape.Body().Mass() < cp.INFINITY { + var nearest cp.Vector + if result.Distance > 0 { + nearest = result.Point + } else { + nearest = mouse + } + + // create a new constraint where the mouse is to draw the body towards the mouse + body := result.Shape.Body() + mouseJoint = cp.NewPivotJoint2(mouseBody, body, cp.Vector{}, body.WorldToLocal(nearest)) + mouseJoint.SetMaxForce(50000) + mouseJoint.SetErrorBias(math.Pow(1.0-0.15, 60.0)) + space.AddConstraint(mouseJoint) + } + } else if raylib.IsMouseButtonReleased(raylib.MouseLeftButton) && mouseJoint != nil { + space.RemoveConstraint(mouseJoint) + mouseJoint = nil + } + + // perform a fixed rate physics tick + accumulator += dt + for accumulator >= physicsTickrate { + space.Step(physicsTickrate) + accumulator -= physicsTickrate + } + raylib.BeginDrawing() - raylib.ClearBackground(raylib.RayWhite) + raylib.BeginMode2D(camera) - game.Update() - - game.Draw() + // this is a generic way to iterate over the shapes in a space, + // to avoid the type switch just keep a pointer to the shapes when they've been created + space.EachShape(func(s *cp.Shape) { + switch s.Class.(type) { + case *cp.Segment: + segment := s.Class.(*cp.Segment) + a := segment.A() + b := segment.B() + raylib.DrawLineV(v(a), v(b), raylib.Black) + case *cp.Circle: + circle := s.Class.(*cp.Circle) + pos := circle.Body().Position() + raylib.DrawCircleV(v(pos), float32(circle.Radius()), raylib.Red) + default: + fmt.Println("unexpected shape", s.Class) + } + }) + raylib.EndMode2D() + raylib.DrawFPS(0, 0) raylib.EndDrawing() } raylib.CloseWindow() } + +func v(v cp.Vector) raylib.Vector2 { + return raylib.Vector2{X: float32(v.X), Y: float32(v.Y)} +}