Add explosion effects

bundle/main.lua

@@ -13,6 +13,10 @@ local cities = {}
 local city_width = 0.07
 local city_height = 0.05
 
+local explosions = {}
+local explosion_radius = 0.05
+local explosion_duration = 0.4
+
 local window_width = nil
 local window_height = nil
 local viewport_x_offset = nil
@@ -91,6 +95,14 @@ function spawnMissile(x, y, target_x, target_y, speed)
 	})
 end
 
+function spawnExplosion(x, y)
+	table.insert(explosions, {
+		x = x,
+		y = y,
+		remaining = explosion_duration,
+	})
+end
+
 function updateMissiles(dt)
 	for _, missile in ipairs(missiles) do
 		missile.x = missile.x + missile.dx * dt
@@ -134,6 +146,7 @@ function updateMissiles(dt)
 			local city_top = city.y - city_height/2
 			local city_bottom = city.y + city_height/2
 			if city.alive and city_left <= missile.x and missile.x <= city_right and city_top <= missile.y and missile.y <= city_bottom then
+				spawnExplosion(missile.x, missile.y)
 				-- Destroy city
 				city.alive = false
 				-- Destroy missile
@@ -159,13 +172,26 @@ function updateMissiles(dt)
 			-- Went off the bottom of the screen or exploded, delete
 			table.remove(missiles, i)
 		else
-			i = i +1
+			i = i + 1
+		end
+	end
+end
+
+function updateExplosions(dt)
+	local i = 1
+	while i <= #explosions do
+		explosions[i].remaining = explosions[i].remaining - dt
+		if explosions[i].remaining < 0 then
+			table.remove(explosions, i)
+		else
+			i = i + 1
 		end
 	end
 end
 
 function love.update(dt)
 	updateMissiles(dt)
+	updateExplosions(dt)
 end
 
 function movePaddle(screen_x)
@@ -248,9 +274,20 @@ function drawCities()
 	end
 end
 
+function drawExplosions()
+	for _, explosion in ipairs(explosions) do
+		local completeness = (explosion_duration - explosion.remaining) / explosion_duration
+		love.graphics.setColor(1, 0, 0)
+		local x, y = toScreenCoordinates(explosion.x, explosion.y)
+		local radius = toScreenSize(completeness ^ 1.5 * explosion_radius)
+		love.graphics.circle('fill', x, y, radius)
+	end
+end
+
 function love.draw()
 	drawCities()
 	drawWalls()
 	drawMissiles()
 	drawPaddle()
+	drawExplosions()
 end