How to create a new item with a mouse click?

[BlakeBarnes00]

So I have been learning LOVE2d for a little bit now, and I am just curious on how I would create a new "block" by clicking on the screen? I have this on my Git to show what I have been doing: https://github.com/BlakeBarnes00/Love2d ... 20-%20Ball

[bobbyjones]

Use the love.mouse pressed callback. Then add a block to your game.

[tuupakku]

Hello Blake,

I assume what you meant is creating a new block at the click of the mouse, instead of repositioning the current one.

Well, looking at the code in objects.lua, in this section:

Code: Select all

	--Creating blocks
	objects.blocks 			= 	{}
	objects.blocks.body 	= 	love.physics.newBody(world.world, 100, 550, "dynamic")
	objects.blocks.shape 	= 	love.physics.newRectangleShape(100, 50)
	objects.blocks.fixture 	= 	love.physics.newFixture(objects.blocks.body, objects.blocks.shape)

your objects.blocks table can only hold a single block. Instead what we want is to make a list of blocks, which leads us to the code:

Code: Select all

	--Creating blocks
	objects.blocks 			= 	{}
	block = {}
	block.body = love.physics.newBody(world.world, 100, 550, "dynamic")
	block.shape = love.physics.newRectangleShape(100, 50)
	block.fixture 	= 	love.physics.newFixture(block.body, block.shape)
	table.insert(objects.blocks, block)

Now we can hold multiple blocks inside our table, now we have to change how we iterate on those blocks to reflect that change. In this part of the code in objects.lua:

Code: Select all

	--Drawing the blocks
	love.graphics.setColor(50, 50, 50) -- set the drawing color to grey for the blocks
  	love.graphics.polygon("fill", objects.blocks.body:getWorldPoints(objects.blocks.shape:getPoints()))

modify it to

Code: Select all

	--Drawing the blocks
	love.graphics.setColor(50, 50, 50) -- set the drawing color to grey for the blocks
	for _, block in pairs(objects.blocks) do
	   love.graphics.polygon("fill", block.body:getWorldPoints(block.shape:getPoints())) 
	end

so that we iterate through our list of blocks and draw all of them.

Next what we want to do is create a new block when the mouse is clicked, rather than changing the position of the current block. So go to controls.lua and find the part where it says:

Code: Select all

		function love.mousepressed( mouseX, mouseY, button, istouch ) -- This is so that we can place the block back down
		if button == 1 then
			objects.blocks.body:setPosition(mouseX, mouseY)
			objects.blocks.body:setLinearVelocity(1, 0)
		end

and change it to:

Code: Select all

		function love.mousepressed( mouseX, mouseY, button, istouch ) -- This is so that we can place the block back down
		if button == 1 then
		    block = {}
	        block.body = love.physics.newBody(world.world, mouseX, mouseY, "dynamic")
			block.body:setLinearVelocity(1, 0)
	        block.shape = love.physics.newRectangleShape(100, 50)
	        block.fixture 	= 	love.physics.newFixture(block.body, block.shape)
	        table.insert(objects.blocks, block)
		end

which is similar to the code which we used to create the first block.

And that's pretty much it! Here's the end result:


This is but one of many ways to do this. With this knowledge you can modify your code to do whatever it needs to

[bobbyjones]

Woah bro nice and thorough. I felt as though he could have discovered the rest. (That and I also didn't have time to write a good response)

[tuupakku]

Woah bro nice and thorough. I felt as though he could have discovered the rest. (That and I also didn't have time to write a good response)

Thanks, I try my best. I replied mostly because I was working on something similar recently, I'm only learning myself, just thought of giving back to the community a little by sharing what I've learned so far.

[BlakeBarnes00]

Hello Blake,

I assume what you meant is creating a new block at the click of the mouse, instead of repositioning the current one.

Well, looking at the code in objects.lua, in this section:

Code: Select all

	--Creating blocks
	objects.blocks 			= 	{}
	objects.blocks.body 	= 	love.physics.newBody(world.world, 100, 550, "dynamic")
	objects.blocks.shape 	= 	love.physics.newRectangleShape(100, 50)
	objects.blocks.fixture 	= 	love.physics.newFixture(objects.blocks.body, objects.blocks.shape)

your objects.blocks table can only hold a single block. Instead what we want is to make a list of blocks, which leads us to the code:

Code: Select all

	--Creating blocks
	objects.blocks 			= 	{}
	block = {}
	block.body = love.physics.newBody(world.world, 100, 550, "dynamic")
	block.shape = love.physics.newRectangleShape(100, 50)
	block.fixture 	= 	love.physics.newFixture(block.body, block.shape)
	table.insert(objects.blocks, block)

Now we can hold multiple blocks inside our table, now we have to change how we iterate on those blocks to reflect that change. In this part of the code in objects.lua:

Code: Select all

	--Drawing the blocks
	love.graphics.setColor(50, 50, 50) -- set the drawing color to grey for the blocks
  	love.graphics.polygon("fill", objects.blocks.body:getWorldPoints(objects.blocks.shape:getPoints()))

modify it to

Code: Select all

	--Drawing the blocks
	love.graphics.setColor(50, 50, 50) -- set the drawing color to grey for the blocks
	for _, block in pairs(objects.blocks) do
	   love.graphics.polygon("fill", block.body:getWorldPoints(block.shape:getPoints())) 
	end

so that we iterate through our list of blocks and draw all of them.

Next what we want to do is create a new block when the mouse is clicked, rather than changing the position of the current block. So go to controls.lua and find the part where it says:

Code: Select all

		function love.mousepressed( mouseX, mouseY, button, istouch ) -- This is so that we can place the block back down
		if button == 1 then
			objects.blocks.body:setPosition(mouseX, mouseY)
			objects.blocks.body:setLinearVelocity(1, 0)
		end

and change it to:

Code: Select all

		function love.mousepressed( mouseX, mouseY, button, istouch ) -- This is so that we can place the block back down
		if button == 1 then
		    block = {}
	        block.body = love.physics.newBody(world.world, mouseX, mouseY, "dynamic")
			block.body:setLinearVelocity(1, 0)
	        block.shape = love.physics.newRectangleShape(100, 50)
	        block.fixture 	= 	love.physics.newFixture(block.body, block.shape)
	        table.insert(objects.blocks, block)
		end

which is similar to the code which we used to create the first block.

And that's pretty much it! Here's the end result:


This is but one of many ways to do this. With this knowledge you can modify your code to do whatever it needs to

Hey man, this was awesome. I just figured out tables today when making another game. Thanks so much!

[tuupakku]

Hey man, this was awesome. I just figured out tables today when making another game. Thanks so much!

No problem mate. Godspeed.