Improve physics and add examples

examples/physics/physac/demo/main.go

@@ -0,0 +1,118 @@
+package main
+
+import (
+	//"fmt"
+
+	"github.com/gen2brain/raylib-go/physics"
+	"github.com/gen2brain/raylib-go/raylib"
+)
+
+func main() {
+	screenWidth := int32(800)
+	screenHeight := int32(450)
+
+	raylib.SetConfigFlags(raylib.FlagMsaa4xHint)
+	raylib.InitWindow(screenWidth, screenHeight, "Physac [raylib] - physics demo")
+
+	// Physac logo drawing position
+	logoX := screenWidth - raylib.MeasureText("Physac", 30) - 10
+	logoY := int32(15)
+
+	// Initialize physics and default physics bodies
+	physics.Init()
+
+	// Create floor rectangle physics body
+	floor := physics.NewBodyRectangle(raylib.NewVector2(float32(screenWidth)/2, float32(screenHeight)), 500, 100, 10)
+	floor.Enabled = false // Disable body state to convert it to static (no dynamics, but collisions)
+
+	// Create obstacle circle physics body
+	circle := physics.NewBodyCircle(raylib.NewVector2(float32(screenWidth)/2, float32(screenHeight)/2), 45, 10)
+	circle.Enabled = false // Disable body state to convert it to static (no dynamics, but collisions)
+
+	raylib.SetTargetFPS(60)
+
+	for !raylib.WindowShouldClose() {
+
+		// Update created physics objects
+		physics.Update()
+
+		if raylib.IsKeyPressed(raylib.KeyR) { // Reset physics input
+			physics.Reset()
+
+			floor = physics.NewBodyRectangle(raylib.NewVector2(float32(screenWidth)/2, float32(screenHeight)), 500, 100, 10)
+			floor.Enabled = false
+
+			circle = physics.NewBodyCircle(raylib.NewVector2(float32(screenWidth)/2, float32(screenHeight)/2), 45, 10)
+			circle.Enabled = false
+		}
+
+		// Physics body creation inputs
+		if raylib.IsMouseButtonPressed(raylib.MouseLeftButton) {
+			physics.NewBodyPolygon(raylib.GetMousePosition(), float32(raylib.GetRandomValue(20, 80)), int(raylib.GetRandomValue(3, 8)), 10)
+		} else if raylib.IsMouseButtonPressed(raylib.MouseRightButton) {
+			physics.NewBodyCircle(raylib.GetMousePosition(), float32(raylib.GetRandomValue(10, 45)), 10)
+		}
+
+		// Destroy falling physics bodies
+		for _, body := range physics.GetBodies() {
+			if body.Position.Y > float32(screenHeight)*2 {
+				physics.DestroyBody(body)
+			}
+		}
+
+		raylib.BeginDrawing()
+
+		raylib.ClearBackground(raylib.Black)
+
+		raylib.DrawFPS(screenWidth-90, screenHeight-30)
+
+		// Draw created physics bodies
+		for i, body := range physics.GetBodies() {
+			//if body.Enabled && body.IsGrounded {
+			//fmt.Printf("%+v\n", body)
+			//fmt.Printf("Velocity: %.6f, %.6f\n", body.Velocity.X, body.Velocity.X)
+			//fmt.Printf("Force: %.6f, %.6f\n", body.Force.X, body.Force.X)
+			//fmt.Printf("AngularVelocity: %.6f\n", body.AngularVelocity)
+			//fmt.Printf("Torque: %.6f\n", body.Torque)
+			//fmt.Printf("Orient: %.6f\n", body.Orient)
+			//fmt.Printf("Inertia: %.6f\n", body.Inertia)
+			//fmt.Printf("InverseInertia: %.6f\n", body.InverseInertia)
+			//fmt.Printf("Mass: %.6f\n", body.Mass)
+			//fmt.Printf("InverseMass: %.6f\n", body.InverseMass)
+			//fmt.Printf("StaticF: %.6f\n", body.StaticFriction)
+			//fmt.Printf("DynamicF: %.6f\n", body.DynamicFriction)
+			//fmt.Printf("Restitution: %.6f\n\n", body.Restitution)
+			//fmt.Println()
+			//}
+
+			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 to create a polygon", 10, 10, 10, raylib.White)
+		raylib.DrawText("Right mouse button to create a circle", 10, 25, 10, raylib.White)
+		raylib.DrawText("Press 'R' to reset example", 10, 40, 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()
+}