Improve physics and add examples

examples/physics/physac/shatter/main.go

@@ -0,0 +1,83 @@
+package main
+
+import (
+	"github.com/gen2brain/raylib-go/physics"
+	"github.com/gen2brain/raylib-go/raylib"
+)
+
+const (
+	velocity = 0.5
+)
+
+func main() {
+	screenWidth := float32(800)
+	screenHeight := float32(450)
+
+	raylib.SetConfigFlags(raylib.FlagMsaa4xHint)
+	raylib.InitWindow(int32(screenWidth), int32(screenHeight), "Physac [raylib] - body shatter")
+
+	// Physac logo drawing position
+	logoX := int32(screenWidth) - raylib.MeasureText("Physac", 30) - 10
+	logoY := int32(15)
+
+	// Initialize physics and default physics bodies
+	physics.Init()
+	physics.SetGravity(0, 0)
+
+	// Create random polygon physics body to shatter
+	physics.NewBodyPolygon(raylib.NewVector2(screenWidth/2, screenHeight/2), float32(raylib.GetRandomValue(80, 200)), int(raylib.GetRandomValue(3, 8)), 10)
+
+	raylib.SetTargetFPS(60)
+
+	for !raylib.WindowShouldClose() {
+		// Update created physics objects
+		physics.Update()
+
+		if raylib.IsKeyPressed(raylib.KeyR) { // Reset physics input
+			physics.Reset()
+
+			// Create random polygon physics body to shatter
+			physics.NewBodyPolygon(raylib.NewVector2(screenWidth/2, screenHeight/2), float32(raylib.GetRandomValue(80, 200)), int(raylib.GetRandomValue(3, 8)), 10)
+		}
+
+		if raylib.IsMouseButtonPressed(raylib.MouseLeftButton) {
+			for _, b := range physics.GetBodies() {
+				b.Shatter(raylib.GetMousePosition(), 10/b.InverseMass)
+			}
+		}
+
+		raylib.BeginDrawing()
+
+		raylib.ClearBackground(raylib.Black)
+
+		// Draw created physics bodies
+		for i, body := range physics.GetBodies() {
+			vertexCount := physics.GetShapeVerticesCount(i)
+			for j := 0; j < vertexCount; j++ {
+				// Get physics bodies shape vertices to draw lines
+				// NOTE: GetShapeVertex() already calculates rotation transformations
+				vertexA := body.GetShapeVertex(j)
+
+				jj := 0
+				if j+1 < vertexCount { // Get next vertex or first to close the shape
+					jj = j + 1
+				}
+
+				vertexB := body.GetShapeVertex(jj)
+
+				raylib.DrawLineV(vertexA, vertexB, raylib.Green) // Draw a line between two vertex positions
+			}
+		}
+
+		raylib.DrawText("Left mouse button in polygon area to shatter body\nPress 'R' to reset example", 10, 10, 10, raylib.White)
+
+		raylib.DrawText("Physac", logoX, logoY, 30, raylib.White)
+		raylib.DrawText("Powered by", logoX+50, logoY-7, 10, raylib.White)
+
+		raylib.EndDrawing()
+	}
+
+	physics.Close() // Unitialize physics
+
+	raylib.CloseWindow()
+}