From 4c400f53709fe9ffd5e0c9d3daea898e0aa9f413 Mon Sep 17 00:00:00 2001
From: Rokas Puzonas <rokas.puz@gmail.com>
Date: Tue, 12 Jul 2022 15:48:36 +0000
Subject: [PATCH] add bouncing bolts

---
 src/systems/debug.lua   |  2 +-
 src/systems/physics.lua | 50 +++++++++++++++++++++++++++++++++++------
 src/systems/player.lua  |  9 ++++----
 3 files changed, 49 insertions(+), 12 deletions(-)

diff --git a/src/systems/debug.lua b/src/systems/debug.lua
index 7952057..b41d1d0 100644
--- a/src/systems/debug.lua
+++ b/src/systems/debug.lua
@@ -4,7 +4,7 @@ local rgb = require("helpers.rgb")
 local DRAW_GRID = false
 local GRID_COLOR = rgb(30, 30, 30)
 
-local DRAW_COLLIDERS = true
+local DRAW_COLLIDERS = false
 local COLLIDER_COLOR = rgb(200, 20, 200)
 
 function Debug:drawColliders()
diff --git a/src/systems/physics.lua b/src/systems/physics.lua
index 1dde92a..34af99b 100644
--- a/src/systems/physics.lua
+++ b/src/systems/physics.lua
@@ -7,6 +7,9 @@ local Vec = require("lib.brinevector")
 
 function Physics:init()
 	self.bump = bump.newWorld()
+	self.boundCollisionFilter = function(...)
+		return self:_collisionFilter(...)
+	end
 end
 
 function Physics:onMapSwitch(map)
@@ -33,8 +36,10 @@ function Physics:removeFromGroup(group, e)
 	end
 end
 
-local function collisionFilter(entity, other)
-	if entity.vel or other.vel then
+function Physics:_collisionFilter(entity, other)
+	if entity.bolt then
+		return "bounce"
+	elseif entity.vel or other.vel then
 		return "slide"
 	end
 end
@@ -43,10 +48,34 @@ function Physics:resolveCollisions(e, dt)
 	local targetPos = e.pos + e.vel * dt
 	local ox = e.collider[1]
 	local oy = e.collider[2]
-	local x, y = self.bump:move(e, targetPos.x+ox, targetPos.y+oy, collisionFilter)
+	local x, y, cols = self.bump:move(e, targetPos.x+ox, targetPos.y+oy, self.boundCollisionFilter)
 
-	local step = Vec(x-ox, y-oy) - e.pos
-	e.vel = step / dt
+	local skip_moving = false
+	if #cols > 0 then
+		e.pos.x = x - ox
+		e.pos.y = y - oy
+		skip_moving = true
+	end
+
+	for _, col in ipairs(cols) do
+		if col.type == "bounce" then
+			-- sx and sy and just number for flipped the direction when something
+			-- bounces.
+			-- When `normal.x` is zero, sx = 1, otherwise sx = -1. Same with sy
+			local sx = 1 - 2*math.abs(col.normal.x)
+			local sy = 1 - 2*math.abs(col.normal.y)
+
+			e.vel.x = e.vel.x * sx
+			e.vel.y = e.vel.y * sy
+			if e.acc then
+				e.acc.x = e.acc.x * sx
+				e.acc.y = e.acc.y * sy
+			end
+			skip_moving = true
+		end
+	end
+
+	return skip_moving
 end
 
 function Physics:update(dt)
@@ -58,11 +87,18 @@ function Physics:update(dt)
 			e.vel = e.vel * (1 - math.min(e.friction, 1)) ^ dt
 		end
 
+		local skip_moving = false
 		if self.pool.groups.collider.hasEntity[e] then
-			self:resolveCollisions(e, dt)
+			skip_moving = self:resolveCollisions(e, dt)
 		end
 
-		e.pos = e.pos + e.vel * dt
+		if not skip_moving then
+			if e.max_speed then
+				e.pos = e.pos + e.vel:trim(e.max_speed) * dt
+			else
+				e.pos = e.pos + e.vel * dt
+			end
+		end
 	end
 end
 
diff --git a/src/systems/player.lua b/src/systems/player.lua
index d9a542e..327e4c6 100644
--- a/src/systems/player.lua
+++ b/src/systems/player.lua
@@ -114,9 +114,10 @@ function Player:tryShootinBolt(player)
 			pos = player.pos + player.aim_dir * 30,
 			vel = player.aim_dir * player.bolt_speed,
 			friction = player.bolt_friction,
+			max_speed = 400,
 			bolt = true,
 			sprite = {},
-			collider = {-4, -4, 4, 4}
+			collider = {-3, -3, 3, 3}
 		}
 	end
 end
@@ -134,10 +135,10 @@ function Player:spawnPlayer()
 		sprite = {},
 		friction = 0.998,
 		speed = 800,
-		bolt_count = 1,
-		bolt_speed = 500,
+		bolt_count = 10,
+		bolt_speed = 2000,
 		bolt_cooldown = 0.2,
-		bolt_friction = 0.9,
+		bolt_friction = 0.98,
 		collider = {-6, -6, 6, 6}
 	}
 end