Physics example to demonstrate how to use the projectile functionality

examples/physics/main.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/harmonica"
+)
+
+const (
+	fps       = 60
+	maxHeight = 100
+)
+
+type frameMsg time.Time
+
+func animate() tea.Cmd {
+	return tea.Tick(time.Second/fps, func(t time.Time) tea.Msg {
+		return frameMsg(t)
+	})
+}
+
+func wait(d time.Duration) tea.Cmd {
+	return func() tea.Msg {
+		time.Sleep(d)
+		return nil
+	}
+}
+
+type model struct {
+	projectile harmonica.Projectile
+	pos        harmonica.Point
+}
+
+func (_ model) Init() tea.Cmd {
+	return tea.Sequentially(wait(time.Second/2), animate())
+}
+
+func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	switch msg.(type) {
+	case tea.KeyMsg:
+		return m, tea.Quit
+
+	// Step forward one frame
+	case frameMsg:
+		m.pos = m.projectile.Update()
+
+		if m.pos.Y > maxHeight {
+			return m, tea.Quit
+		}
+
+		return m, animate()
+	default:
+		return m, nil
+	}
+}
+
+func (m model) View() string {
+	var out strings.Builder
+
+	for y := 0; y < int(m.pos.Y); y++ {
+		out.WriteString("\n")
+	}
+
+	for x := 0; x < int(m.pos.X); x++ {
+		out.WriteString(" ")
+	}
+	out.WriteString(fmt.Sprintf("(%.2f, %.2f)", m.pos.X, m.pos.Y))
+
+	return out.String()
+}
+
+func main() {
+	initPos := harmonica.Point{X: 0, Y: 0}
+	initVel := harmonica.Vector{X: 5, Y: 0}
+	initAcc := harmonica.TerminalGravity
+	m := model{
+		projectile: harmonica.NewProjectile(harmonica.FPS(fps), initPos, initVel, initAcc),
+	}
+
+	if err := tea.NewProgram(m).Start(); err != nil {
+		fmt.Println("Error running program:", err)
+		os.Exit(1)
+	}
+}