From 88ecbf63625e3ce4c4fcfb9f19b0594ea88d007c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dawid=20Wysoki=C5=84ski?= <contact@dwysokinski.me>
Date: Sat, 2 Dec 2023 07:48:46 +0000
Subject: [PATCH] feat: random direction of the ball at the beginning of the
 match/after a restart (#4)

Reviewed-on: https://gitea.dwysokinski.me/classic-games/tennis-game/pulls/4
---
 internal/ball.go | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/internal/ball.go b/internal/ball.go
index f9b18c3..e4a2ffb 100644
--- a/internal/ball.go
+++ b/internal/ball.go
@@ -3,6 +3,8 @@ package internal
 import (
 	"image"
 	"image/color"
+	"math/rand"
+	"time"
 
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/vector"
@@ -20,23 +22,25 @@ type ball struct {
 
 const (
 	ballBaseRadius = 5
-	ballBaseSpeedX = 1
-	ballBaseSpeedY = 1
+	ballBaseSpeedX = 1.5
+	ballBaseSpeedY = 1.5
 )
 
 func newBall(screenWidth, screenHeight int) *ball {
 	fScreenWidth := float32(screenWidth)
 	fScreenHeight := float32(screenHeight)
+
 	r := ballBaseRadius * fScreenHeight / BaseHeight
 	x := fScreenWidth/2.0 - r
 	y := fScreenHeight/2.0 - r
+
 	return &ball{
 		x:      x,
 		y:      y,
 		initX:  x,
 		initY:  y,
-		speedX: ballBaseSpeedX * fScreenWidth / BaseWidth,
-		speedY: ballBaseSpeedY * fScreenHeight / BaseHeight,
+		speedX: randSpeedDirection() * ballBaseSpeedX * fScreenWidth / BaseWidth,
+		speedY: randSpeedDirection() * ballBaseSpeedY * fScreenHeight / BaseHeight,
 		r:      r,
 	}
 }
@@ -99,6 +103,8 @@ func (b *ball) nextSpeed(bounds image.Rectangle, obstacles ...image.Rectangle) (
 func (b *ball) reset() {
 	b.x = b.initX
 	b.y = b.initY
+	b.speedX *= randSpeedDirection()
+	b.speedY *= randSpeedDirection()
 }
 
 func (b *ball) resize(x, y float32) {
@@ -114,3 +120,14 @@ func (b *ball) resize(x, y float32) {
 func (b *ball) bounds() image.Rectangle {
 	return image.Rect(int(b.x-b.r), int(b.y-b.r), int(b.x+b.r), int(b.y+b.r))
 }
+
+func randSpeedDirection() float32 {
+	//nolint:gosec
+	r := rand.New(rand.NewSource(time.Now().Unix()))
+
+	if r.Intn(101) >= 50 {
+		return -1
+	}
+
+	return 1
+}