From 77426a0b63168858f4e7af8475b110fa3ad779d3 Mon Sep 17 00:00:00 2001
From: Dan Cojocaru <dancojocaru2010@hotmail.com>
Date: Mon, 21 Mar 2022 01:59:09 +0200
Subject: [PATCH] Added ball physics

---
 src/main.cpp | 63 +++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 52 insertions(+), 11 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 99e527c..b54c261 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,3 +1,4 @@
+#include <iostream>
 #include <functional>
 #include <string>
 #include <cmath>
@@ -42,11 +43,13 @@ public:
 
 class Ball : public Drawable {
 public:
+	static constexpr GLfloat defaultVeloX = 0.5;
+
 	GLfloat radius;
 	GLfloat x, y;
 	GLfloat veloX, veloY;
 
-	Ball(GLfloat x, GLfloat y) : x(x), y(y), radius(0.025), veloX(0.4) {
+	Ball(GLfloat x, GLfloat y) : x(x), y(y), radius(0.025), veloX(defaultVeloX) {
 
 	}
 
@@ -121,7 +124,7 @@ void display(void) {
 
 int gameTime;
 
-const GLfloat paddleMoveSpeed = 0.75;
+const GLfloat paddleMoveSpeed = 0.8;
 
 void idle() {
 	int newTime = glutGet(GLUT_ELAPSED_TIME);
@@ -131,17 +134,55 @@ void idle() {
 	if (gameRunning) {
 		ball.update();
 
-		// Move paddle
-		leftPaddle.y += leftMove * paddleMoveSpeed * deltaTime;
-		rightPaddle.y += rightMove * paddleMoveSpeed * deltaTime;
-
-		// Clamp paddle to stay on screen
-		if (leftPaddle.y < -1) leftPaddle.y = -1;
-		if (rightPaddle.y < -1) rightPaddle.y = -1;
-		if (leftPaddle.y > 1 - leftPaddle.height) leftPaddle.y = 1 - leftPaddle.height;
-		if (rightPaddle.y > 1 - rightPaddle.height) rightPaddle.y = 1 - rightPaddle.height;
+		// Detect ball collission
+		if (leftPaddle.x <= (ball.x + ball.radius) && (ball.x - ball.radius) <= (leftPaddle.x + leftPaddle.width)) {
+			// Ball inside left-right area of left paddle
+			if (leftPaddle.y <= ball.y && ball.y <= leftPaddle.y + leftPaddle.height) {
+				// Ball inside up-down area of left paddle
+				ball.veloX = ball.defaultVeloX;
+				ball.veloY = Utils::nummap(ball.y, leftPaddle.y, leftPaddle.y + leftPaddle.height, (GLfloat)-1, (GLfloat)1);
+			}
+		}
+		else if (rightPaddle.x <= (ball.x + ball.radius) && (ball.x - ball.radius) <= (rightPaddle.x + rightPaddle.width)) {
+			// Ball inside left-right area of right paddle
+			if (rightPaddle.y <= ball.y && ball.y <= rightPaddle.y + rightPaddle.height) {
+				// Ball inside up-down area of right paddle
+				ball.veloX = -ball.defaultVeloX;
+				ball.veloY = Utils::nummap(ball.y, rightPaddle.y, rightPaddle.y + rightPaddle.height, (GLfloat)-1, (GLfloat)1);
+			}
+		}
+		else if (ball.x + ball.radius < -1) {
+			// Ball exited board on the left side
+			rightScore += 1;
+			ball.x = ball.y = 0;
+			gameRunning = false;
+		}
+		else if (ball.x - ball.radius > 1) {
+			// Ball exited board on the right side
+			leftScore += 1;
+			ball.x = ball.y = 0;
+			gameRunning = false;
+		}
+		else if (ball.y - ball.radius < -1) {
+			// Ball touched bottom side
+			ball.veloY *= -1;
+		}
+		else if (ball.y + ball.radius > 1) {
+			// Ball touched top side
+			ball.veloY *= -1;
+		}
 	}
 
+	// Move paddle
+	leftPaddle.y += leftMove * paddleMoveSpeed * deltaTime;
+	rightPaddle.y += rightMove * paddleMoveSpeed * deltaTime;
+
+	// Clamp paddle to stay on screen
+	if (leftPaddle.y < -1) leftPaddle.y = -1;
+	if (rightPaddle.y < -1) rightPaddle.y = -1;
+	if (leftPaddle.y > 1 - leftPaddle.height) leftPaddle.y = 1 - leftPaddle.height;
+	if (rightPaddle.y > 1 - rightPaddle.height) rightPaddle.y = 1 - rightPaddle.height;
+
 	glutPostRedisplay();
 }