From a899bc060b6180635f3ff4ac73b7e6aee4fe9a7b Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Mon, 22 Aug 2022 20:18:30 +0200
Subject: Implemented a ball with basic physics and collisions

---
 src/brothers.zig | 31 ++++++++++++++++++++++++++++++-
 src/game.zig     |  9 +++++++--
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/brothers.zig b/src/brothers.zig
index 7aaf7de..448aaec 100644
--- a/src/brothers.zig
+++ b/src/brothers.zig
@@ -1,6 +1,8 @@
 const std = @import("std");
 const spoon = @import("spoon");
 
+const ball = @import("ball.zig");
+
 pub const Side = enum(u1) {
     left,
     right,
@@ -41,7 +43,7 @@ pub const Brother = struct {
         self.dx += 5 / (1000 / 60.0);
         self.moveDuration = 24;
     }
-    pub fn step(self: *Brother) void {
+    pub fn step(self: *Brother, b: *ball.Ball) void {
         // Horizontal movement
         const x = self.x + self.dx;
         const ll = leftLimit[@enumToInt(self.side)];
@@ -74,6 +76,33 @@ pub const Brother = struct {
         } else {
             self.y = y;
         }
+        // Check for ball collisions
+        if (b.y >= y and b.y <= y + 2 and b.x >= x and b.x < x + 5) {
+            if (b.dy > 0) {
+                b.dy = -b.dy / 1.5;
+            }
+            b.dx = b.dx / 2.0;
+            var strength: f64 = 1;
+            if (b.dx > 0 and self.dx < 0)
+                strength *= 2; // moving in opposite directions
+            if (y < 12) { // jumping
+                strength *= 2;
+            }
+            if (b.x < x + 1) {
+                b.dx -= strength * 4 / (1000 / 60.0);
+            } else if (b.x < x + 2) {
+                b.dx -= strength * 2 / (1000 / 60.0);
+            } else if (b.x < x + 3) {
+                var modifier: f64 = 1;
+                if (self.side == .left) modifier = -1;
+                b.dx += modifier * strength * 2 / (1000 / 60.0);
+            } else if (b.x < x + 4) {
+                b.dx += strength * 2 / (1000 / 60.0);
+            } else {
+                b.dx += strength * 4 / (1000 / 60.0);
+            }
+            b.dy = b.dy * strength - 0.04;
+        }
     }
     pub fn reset(self: *Brother, side: ?Side) void {
         if (side) |s| {
diff --git a/src/game.zig b/src/game.zig
index 8af1889..c8492df 100644
--- a/src/game.zig
+++ b/src/game.zig
@@ -1,16 +1,19 @@
 const std = @import("std");
 const spoon = @import("spoon");
 
+const ball = @import("ball.zig");
 const brothers = @import("brothers.zig");
 const playfield = @import("playfield.zig");
 
 pub const Game = struct {
+    ball: ball.Ball = undefined,
     brothers: [2]brothers.Brother = undefined,
     side: brothers.Side = undefined,
     pub fn draw(self: Game, rc: *spoon.Term.RenderContext) !void {
         try playfield.draw(rc);
         try self.brothers[0].draw(rc);
         try self.brothers[1].draw(rc);
+        try self.ball.draw(rc);
     }
     pub fn moveJump(self: *Game, side: brothers.Side) void {
         self.brothers[@enumToInt(side)].moveJump();
@@ -26,11 +29,13 @@ pub const Game = struct {
         self.resetRound();
     }
     pub fn resetRound(self: *Game) void {
+        self.ball.reset(.left);
         self.brothers[0].reset(.left);
         self.brothers[1].reset(.right);
     }
     pub fn step(self: *Game) void {
-        self.brothers[0].step();
-        self.brothers[1].step();
+        self.ball.step();
+        self.brothers[0].step(&self.ball);
+        self.brothers[1].step(&self.ball);
     }
 };
-- 
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