From 39264dc723580f99d91a2d3cfd2acda23b32b874 Mon Sep 17 00:00:00 2001 From: Milan Nikolic Date: Sun, 5 Mar 2017 22:54:34 +0100 Subject: [PATCH] Physics examples --- examples/physics/box2d/main.go | 513 ++++++++++++++++++++++++++++++ examples/physics/chipmunk/main.go | 139 ++++++++ 2 files changed, 652 insertions(+) create mode 100644 examples/physics/box2d/main.go create mode 100644 examples/physics/chipmunk/main.go diff --git a/examples/physics/box2d/main.go b/examples/physics/box2d/main.go new file mode 100644 index 0000000..a053a4b --- /dev/null +++ b/examples/physics/box2d/main.go @@ -0,0 +1,513 @@ +package main + +import ( + "math" + "math/rand" + + "github.com/gen2brain/raylib-go/raylib" + + box2d "github.com/neguse/go-box2d-lite/box2dlite" +) + +// Game type +type Game struct { + World *box2d.World + TimeStep float64 +} + +// NewGame - Start new game +func NewGame() (g Game) { + g.Init() + return +} + +// Init - Initialize game +func (g *Game) Init() { + gravity := box2d.Vec2{0.0, -10.0} + g.World = box2d.NewWorld(gravity, 10) // 10 iterations +} + +// Update - Update game +func (g *Game) Update() { + // Keys 1-9 switch demos + switch raylib.GetKeyPressed() { + case raylib.KeyOne: + g.Demo1() + case raylib.KeyTwo: + g.Demo2() + case raylib.KeyThree: + g.Demo3() + case raylib.KeyFour: + g.Demo4() + case raylib.KeyFive: + g.Demo5() + case raylib.KeySix: + g.Demo6() + case raylib.KeySeven: + g.Demo7() + case raylib.KeyEight: + g.Demo8() + case raylib.KeyNine: + g.Demo9() + } + + g.TimeStep = float64(raylib.GetFrameTime()) + + // Physics steps calculations + g.World.Step(g.TimeStep) +} + +// Draw - Draw game +func (g *Game) Draw() { + for _, b := range g.World.Bodies { + g.DrawBody(b) + } + for _, j := range g.World.Joints { + g.DrawJoint(j) + } + + raylib.DrawText("Use keys 1-9 to switch current demo", 20, 20, 10, raylib.RayWhite) +} + +// DrawBody - Draw body +func (g *Game) DrawBody(b *box2d.Body) { + R := box2d.Mat22ByAngle(b.Rotation) + x := b.Position + h := box2d.MulSV(0.5, b.Width) + + o := box2d.Vec2{400, 400} + S := box2d.Mat22{box2d.Vec2{20.0, 0.0}, box2d.Vec2{0.0, -20.0}} + + v1 := o.Add(S.MulV(x.Add(R.MulV(box2d.Vec2{-h.X, -h.Y})))) + v2 := o.Add(S.MulV(x.Add(R.MulV(box2d.Vec2{h.X, -h.Y})))) + v3 := o.Add(S.MulV(x.Add(R.MulV(box2d.Vec2{h.X, h.Y})))) + v4 := o.Add(S.MulV(x.Add(R.MulV(box2d.Vec2{-h.X, h.Y})))) + + raylib.DrawLine(int32(v1.X), int32(v1.Y), int32(v2.X), int32(v2.Y), raylib.RayWhite) + raylib.DrawLine(int32(v2.X), int32(v2.Y), int32(v3.X), int32(v3.Y), raylib.RayWhite) + raylib.DrawLine(int32(v3.X), int32(v3.Y), int32(v4.X), int32(v4.Y), raylib.RayWhite) + raylib.DrawLine(int32(v4.X), int32(v4.Y), int32(v1.X), int32(v1.Y), raylib.RayWhite) +} + +// DrawJoint - Draw joint +func (g *Game) DrawJoint(j *box2d.Joint) { + b1 := j.Body1 + b2 := j.Body2 + + R1 := box2d.Mat22ByAngle(b1.Rotation) + R2 := box2d.Mat22ByAngle(b2.Rotation) + + x1 := b1.Position + p1 := x1.Add(R1.MulV(j.LocalAnchor1)) + + x2 := b2.Position + p2 := x2.Add(R2.MulV(j.LocalAnchor2)) + + o := box2d.Vec2{400, 400} + S := box2d.Mat22{box2d.Vec2{20.0, 0.0}, box2d.Vec2{0.0, -20.0}} + + x1 = o.Add(S.MulV(x1)) + p1 = o.Add(S.MulV(p1)) + x2 = o.Add(S.MulV(x2)) + p2 = o.Add(S.MulV(p2)) + + raylib.DrawLine(int32(x1.X), int32(x1.Y), int32(p1.X), int32(p1.Y), raylib.RayWhite) + raylib.DrawLine(int32(x2.X), int32(x2.Y), int32(p2.X), int32(p2.Y), raylib.RayWhite) +} + +// Demo1 - Single box +func (g *Game) Demo1() { + g.World.Clear() + + var b1, b2 box2d.Body + + b1.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b1.Position = box2d.Vec2{0.0, -0.5 * b1.Width.Y} + g.World.AddBody(&b1) + + b2.Set(&box2d.Vec2{1.0, 1.0}, 200.0) + b2.Position = box2d.Vec2{0.0, 4.0} + g.World.AddBody(&b2) +} + +// Demo2 - A simple pendulum +func (g *Game) Demo2() { + g.World.Clear() + + var b2, b1 box2d.Body + var j box2d.Joint + + b1.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b1.Friction = 0.2 + b1.Position = box2d.Vec2{0.0, -0.5 * b1.Width.Y} + b1.Rotation = 0.0 + g.World.AddBody(&b1) + + b2.Set(&box2d.Vec2{1.0, 1.0}, 100.0) + b2.Friction = 0.2 + b2.Position = box2d.Vec2{9.0, 11.0} + b2.Rotation = 0.0 + g.World.AddBody(&b2) + + j.Set(&b1, &b2, &box2d.Vec2{0.0, 11.0}) + g.World.AddJoint(&j) +} + +// Demo3 - Varying friction coefficients +func (g *Game) Demo3() { + g.World.Clear() + + { + var b box2d.Body + b.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b.Position = box2d.Vec2{0.0, -0.5 * b.Width.Y} + g.World.AddBody(&b) + } + + { + var b box2d.Body + b.Set(&box2d.Vec2{13.0, 0.25}, math.MaxFloat64) + b.Position = box2d.Vec2{-2.0, 11.0} + b.Rotation = -0.25 + g.World.AddBody(&b) + } + + { + var b box2d.Body + b.Set(&box2d.Vec2{0.25, 1.0}, math.MaxFloat64) + b.Position = box2d.Vec2{5.25, 9.5} + g.World.AddBody(&b) + } + + { + var b box2d.Body + b.Set(&box2d.Vec2{13.0, 0.25}, math.MaxFloat64) + b.Position = box2d.Vec2{2.0, 7.0} + b.Rotation = 0.25 + g.World.AddBody(&b) + } + + { + var b box2d.Body + b.Set(&box2d.Vec2{0.25, 1.0}, math.MaxFloat64) + b.Position = box2d.Vec2{-5.25, 5.5} + g.World.AddBody(&b) + } + + frictions := []float64{0.75, 0.5, 0.35, 0.1, 0.0} + for i := 0; i < 5; i++ { + var b box2d.Body + b.Set(&box2d.Vec2{0.5, 0.5}, 25.0) + b.Friction = frictions[i] + b.Position = box2d.Vec2{-7.5 + 2.0*float64(i), 14.0} + g.World.AddBody(&b) + } + +} + +// Demo4 - A vertical stack +func (g *Game) Demo4() { + g.World.Clear() + + { + var b box2d.Body + b.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b.Friction = 0.2 + b.Position = box2d.Vec2{0.0, -0.5 * b.Width.Y} + b.Rotation = 0.0 + g.World.AddBody(&b) + } + + for i := 0; i < 10; i++ { + var b box2d.Body + b.Set(&box2d.Vec2{1.0, 1.0}, 1.0) + b.Friction = 0.2 + x := rand.Float64()*0.2 - 0.1 + b.Position = box2d.Vec2{x, 0.51 + 1.05*float64(i)} + g.World.AddBody(&b) + } + +} + +// Demo5 - A pyramid +func (g *Game) Demo5() { + g.World.Clear() + + { + var b box2d.Body + b.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b.Friction = 0.2 + b.Position = box2d.Vec2{0.0, -0.5 * b.Width.Y} + b.Rotation = 0.0 + g.World.AddBody(&b) + } + + x := box2d.Vec2{-6.0, 0.75} + + for i := 0; i < 12; i++ { + y := x + for j := i; j < 12; j++ { + var b box2d.Body + b.Set(&box2d.Vec2{1.0, 1.0}, 10.0) + b.Friction = 0.2 + b.Position = y + g.World.AddBody(&b) + + y = y.Add(box2d.Vec2{1.125, 0.0}) + } + + x = x.Add(box2d.Vec2{0.5625, 2.0}) + } +} + +// Demo6 - A teeter +func (g *Game) Demo6() { + g.World.Clear() + + var b1, b2, b3, b4, b5 box2d.Body + b1.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b1.Position = box2d.Vec2{0.0, -0.5 * b1.Width.Y} + g.World.AddBody(&b1) + + b2.Set(&box2d.Vec2{12.0, 0.25}, 100) + b2.Position = box2d.Vec2{0.0, 1.0} + g.World.AddBody(&b2) + + b3.Set(&box2d.Vec2{0.5, 0.5}, 25.0) + b3.Position = box2d.Vec2{-5.0, 2.0} + g.World.AddBody(&b3) + + b4.Set(&box2d.Vec2{0.5, 0.5}, 25.0) + b4.Position = box2d.Vec2{-5.5, 2.0} + g.World.AddBody(&b4) + + b5.Set(&box2d.Vec2{1.0, 1.0}, 100) + b5.Position = box2d.Vec2{5.5, 15.0} + g.World.AddBody(&b5) + + { + var j box2d.Joint + j.Set(&b1, &b2, &box2d.Vec2{0.0, 1.0}) + g.World.AddJoint(&j) + } + +} + +// Demo7 - A suspension bridge +func (g *Game) Demo7() { + g.World.Clear() + + var ba []*box2d.Body + + { + var b box2d.Body + b.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b.Friction = 0.2 + b.Position = box2d.Vec2{0.0, -0.5 * b.Width.Y} + b.Rotation = 0.0 + g.World.AddBody(&b) + ba = append(ba, &b) + } + + const numPlunks = 15 + const mass = 50.0 + + for i := 0; i < numPlunks; i++ { + var b box2d.Body + b.Set(&box2d.Vec2{1.0, 0.25}, mass) + b.Friction = 0.2 + b.Position = box2d.Vec2{-8.5 + 1.25*float64(i), 5.0} + g.World.AddBody(&b) + ba = append(ba, &b) + } + + // Tuning + const frequencyHz = 2.0 + const dampingRatio = 0.7 + + // Frequency in radians + const omega = 2.0 * math.Pi * frequencyHz + + // Damping coefficient + const d = 2.0 * mass * dampingRatio * omega + + // Spring stifness + const k = mass * omega * omega + + // Magic formulas + softness := 1.0 / (d + g.TimeStep*k) + biasFactor := g.TimeStep * k / (d + g.TimeStep*k) + + for i := 0; i <= numPlunks; i++ { + var j box2d.Joint + j.Set(ba[i], ba[(i+1)%(numPlunks+1)], &box2d.Vec2{-9.125 + 1.25*float64(i), 5.0}) + j.Softness = softness + j.BiasFactor = biasFactor + g.World.AddJoint(&j) + } + +} + +// Demo8 - Dominos +func (g *Game) Demo8() { + g.World.Clear() + + var b1 box2d.Body + b1.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b1.Position = box2d.Vec2{0.0, -0.5 * b1.Width.Y} + g.World.AddBody(&b1) + + { + var b box2d.Body + b.Set(&box2d.Vec2{12.0, 0.5}, math.MaxFloat64) + b.Position = box2d.Vec2{-1.5, 10.0} + g.World.AddBody(&b) + } + + for i := 0; i < 10; i++ { + var b box2d.Body + b.Set(&box2d.Vec2{0.2, 2.0}, 10.0) + b.Position = box2d.Vec2{-6.0 + 1.0*float64(i), 11.125} + b.Friction = 0.1 + g.World.AddBody(&b) + } + + { + var b box2d.Body + b.Set(&box2d.Vec2{14.0, 0.5}, math.MaxFloat64) + b.Position = box2d.Vec2{1.0, 6.0} + b.Rotation = 0.3 + g.World.AddBody(&b) + } + + var b2 box2d.Body + b2.Set(&box2d.Vec2{0.5, 3.0}, math.MaxFloat64) + b2.Position = box2d.Vec2{-7.0, 4.0} + g.World.AddBody(&b2) + + var b3 box2d.Body + b3.Set(&box2d.Vec2{12.0, 0.25}, 20.0) + b3.Position = box2d.Vec2{-0.9, 1.0} + g.World.AddBody(&b3) + + { + var j box2d.Joint + j.Set(&b1, &b3, &box2d.Vec2{-2.0, 1.0}) + g.World.AddJoint(&j) + } + + var b4 box2d.Body + b4.Set(&box2d.Vec2{0.5, 0.5}, 10.0) + b4.Position = box2d.Vec2{-10.0, 15.0} + g.World.AddBody(&b4) + + { + var j box2d.Joint + j.Set(&b2, &b4, &box2d.Vec2{-7.0, 15.0}) + g.World.AddJoint(&j) + } + + var b5 box2d.Body + b5.Set(&box2d.Vec2{2.0, 2.0}, 20.0) + b5.Position = box2d.Vec2{6.0, 2.5} + b5.Friction = 0.1 + g.World.AddBody(&b5) + + { + var j box2d.Joint + j.Set(&b1, &b5, &box2d.Vec2{6.0, 2.6}) + g.World.AddJoint(&j) + } + + var b6 box2d.Body + b6.Set(&box2d.Vec2{2.0, 0.2}, 10.0) + b6.Position = box2d.Vec2{6.0, 3.6} + g.World.AddBody(&b6) + + { + var j box2d.Joint + j.Set(&b5, &b6, &box2d.Vec2{7.0, 3.5}) + g.World.AddJoint(&j) + } + +} + +// Demo9 - A multi-pendulum +func (g *Game) Demo9() { + g.World.Clear() + + var b1 *box2d.Body + + { + var b box2d.Body + b.Set(&box2d.Vec2{100.0, 20.0}, math.MaxFloat64) + b.Position = box2d.Vec2{0.0, -0.5 * b.Width.Y} + g.World.AddBody(&b) + b1 = &b + } + + const mass = 10.0 + + // Tuning + const frequencyHz = 4.0 + const dampingRatio = 0.7 + + // Frequency in radians + const omega = 2.0 * math.Pi * frequencyHz + + // Damping coefficient + const d = 2.0 * mass * dampingRatio * omega + + // Spring stiffness + const k = mass * omega * omega + + // Magic formulas + softness := 1.0 / (d + g.TimeStep*k) + biasFactor := g.TimeStep * k / (d + g.TimeStep*k) + + const y = 12.0 + + for i := 0; i < 15; i++ { + x := box2d.Vec2{0.5 + float64(i), y} + + var b box2d.Body + b.Set(&box2d.Vec2{0.75, 0.25}, mass) + b.Friction = 0.2 + b.Position = x + b.Rotation = 0.0 + g.World.AddBody(&b) + + var j box2d.Joint + j.Set(b1, &b, &box2d.Vec2{float64(i), y}) + j.Softness = softness + j.BiasFactor = biasFactor + g.World.AddJoint(&j) + + b1 = &b + } + +} + +func main() { + raylib.InitWindow(800, 450, "raylib [physics] example - box2d") + + raylib.SetTargetFPS(60) + + game := NewGame() + + game.Demo1() + + for !raylib.WindowShouldClose() { + raylib.BeginDrawing() + + raylib.ClearBackground(raylib.Black) + + game.Update() + + game.Draw() + + raylib.EndDrawing() + } + + raylib.CloseWindow() +} diff --git a/examples/physics/chipmunk/main.go b/examples/physics/chipmunk/main.go new file mode 100644 index 0000000..f477d99 --- /dev/null +++ b/examples/physics/chipmunk/main.go @@ -0,0 +1,139 @@ +package main + +import ( + "math" + "math/rand" + + "github.com/gen2brain/raylib-go/raylib" + + "github.com/vova616/chipmunk" + "github.com/vova616/chipmunk/vect" +) + +const ( + ballRadius = 25 + ballMass = 1 +) + +// Game type +type Game struct { + Space *chipmunk.Space + Balls []*chipmunk.Shape + StaticLines []*chipmunk.Shape + + ticksToNextBall int +} + +// NewGame - Start new game +func NewGame() (g Game) { + g.Init() + return +} + +// Init - Initialize game +func (g *Game) Init() { + g.createBodies() + + g.ticksToNextBall = 10 +} + +// Update - Update game +func (g *Game) Update() { + g.ticksToNextBall-- + if g.ticksToNextBall == 0 { + g.ticksToNextBall = rand.Intn(100) + 1 + g.addBall() + } + + // 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 + } + } +} + +func main() { + raylib.InitWindow(800, 450, "raylib [physics] example - chipmunk") + + raylib.SetTargetFPS(60) + + game := NewGame() + + for !raylib.WindowShouldClose() { + raylib.BeginDrawing() + + raylib.ClearBackground(raylib.RayWhite) + + game.Update() + + game.Draw() + + raylib.EndDrawing() + } + + raylib.CloseWindow() +}