Lua Programming Help Thread

[_-Tiger-_]

Ok i was wondering if anyone could give me a link to a tut that shows me how to add a menu for my game, like main menu, and animation... Thanks if you can.

[xpack]

http://www.evilmana.com/tutorials/co...imple_menu.php
http://www.evilmana.com/tutorials/co...enu_nathan.php
http://www.evilmana.com/tutorials/codebase/menu.php

Theres three of them

[_-Tiger-_]

Ok heres my code so far

--Colors
white = Color.new(255,255,255)
red = Color.new(255,0,0)

current = 1 --this is our current menu selection
oldpad = Controls.read()
while true do
pad = Controls.read()
screen:clear()
screen:print(240,100,"Single Player",white)
screen:print(240,110,"Options",white)
screen:print(240,120,"Exit",white)
if current == 1 then
screen:print(240,100,"Single Player",red)
end
if current == 2 then
screen:print(240,110,"Options",red)
end
screen:print(240,120,"Exit",red)
end
if pad:up() and oldpad:up() ~= pad:up() then
current = current - 1
end
if pad:down() and oldpad:down() ~= pad:down() then
current = current + 1
end
if current == 6 then
current = 1
end
if current == 0 then
current = 5
end
screen.waitVblankStart()
screen.flip()
oldpad = pad
end

if pad:cross() and current == 1 then
Single = Player(
screen:clear()
)background = Image.load("images/background.jpg")
player2 = Image.load("images/player2.png")
end
if pad:cross() and current == 2 then
Options()
end
if pad:cross() and current == 3 then
Exit()
end

But when i press X in the menu, nothing happens, any help?
Oh and is there any tutorials on like making the screen scroll to see the rest of a map (like in Halo Genocide, if u keep moving right the screen will start to scroll)?

[Da_MerV]

anyone ever seen this error?

libpng error: Too many IDAT's found

i have a feeling its from loading over 50 pngs but i thought i deleted them by setting them to nil. this does delete them correct?

[almost219]

Ok heres my code so far

--Colors
white = Color.new(255,255,255)
red = Color.new(255,0,0)

current = 1 --this is our current menu selection
oldpad = Controls.read()
while true do
pad = Controls.read()
screen:clear()
screen:print(240,100,"Single Player",white)
screen:print(240,110,"Options",white)
screen:print(240,120,"Exit",white)
if current == 1 then
screen:print(240,100,"Single Player",red)
end
if current == 2 then
screen:print(240,110,"Options",red)
end
screen:print(240,120,"Exit",red)
end
if pad:up() and oldpad:up() ~= pad:up() then
current = current - 1
end
if pad:down() and oldpad:down() ~= pad:down() then
current = current + 1
end
if current == 6 then
current = 1
end
if current == 0 then
current = 5
end
screen.waitVblankStart()
screen.flip()
oldpad = pad
end

if pad:cross() and current == 1 then
Single = Player(
screen:clear()
)background = Image.load("images/background.jpg")
player2 = Image.load("images/player2.png")
end
if pad:cross() and current == 2 then
Options()
end
if pad:cross() and current == 3 then
Exit()
end

But when i press X in the menu, nothing happens, any help?
Oh and is there any tutorials on like making the screen scroll to see the rest of a map (like in Halo Genocide, if u keep moving right the screen will start to scroll)?

1. clicking x on current 1 only set variables
2. have you written the functions for Options() and Exit()

[EminentJonFrost]

Ok heres my code so far

--Colors
white = Color.new(255,255,255)
red = Color.new(255,0,0)

current = 1 --this is our current menu selection
oldpad = Controls.read()
while true do
pad = Controls.read()
screen:clear()
screen:print(240,100,"Single Player",white)
screen:print(240,110,"Options",white)
screen:print(240,120,"Exit",white)
if current == 1 then
screen:print(240,100,"Single Player",red)
end
if current == 2 then
screen:print(240,110,"Options",red)
end
screen:print(240,120,"Exit",red)
end
if pad:up() and oldpad:up() ~= pad:up() then
current = current - 1
end
if pad:down() and oldpad:down() ~= pad:down() then
current = current + 1
end
if current == 6 then
current = 1
end
if current == 0 then
current = 5
end
screen.waitVblankStart()
screen.flip()
oldpad = pad
end

if pad:cross() and current == 1 then
Single = Player(
screen:clear()
)background = Image.load("images/background.jpg")
player2 = Image.load("images/player2.png")
end
if pad:cross() and current == 2 then
Options()
end
if pad:cross() and current == 3 then
Exit()
end

But when i press X in the menu, nothing happens, any help?
Oh and is there any tutorials on like making the screen scroll to see the rest of a map (like in Halo Genocide, if u keep moving right the screen will start to scroll)?

very easy, just put this:

if pad:cross() and current == 1 then
Single = Player(
screen:clear()
)background = Image.load("images/background.jpg")
player2 = Image.load("images/player2.png")
end
if pad:cross() and current == 2 then
Options()
end
if pad:cross() and current == 3 then
Exit()
end

in the 'while' loop, you have it outside.

--Colors
white = Color.new(255,255,255)
red = Color.new(255,0,0)

current = 1 --this is our current menu selection
oldpad = Controls.read()
while true do
pad = Controls.read()
screen:clear()
screen:print(240,100,"Single Player",white)
screen:print(240,110,"Options",white)
screen:print(240,120,"Exit",white)
if current == 1 then
screen:print(240,100,"Single Player",red)
end
if current == 2 then
screen:print(240,110,"Options",red)
end
screen:print(240,120,"Exit",red)
end
if pad:up() and oldpad:up() ~= pad:up() then
current = current - 1
end
if pad:down() and oldpad:down() ~= pad:down() then
current = current + 1
end
if current == 6 then
current = 1
end
if current == 0 then
current = 5
end

if pad:cross() and current == 1 then
Single = Player(
screen:clear()
)background = Image.load("images/background.jpg")
player2 = Image.load("images/player2.png")
end
if pad:cross() and current == 2 then
Options()
end
if pad:cross() and current == 3 then
Exit()
end

screen.waitVblankStart()
screen.flip()
oldpad = pad
end

[almost219]

Ok heres my code so far

--Colors
white = Color.new(255,255,255)
red = Color.new(255,0,0)

current = 1 --this is our current menu selection
oldpad = Controls.read()
while true do
pad = Controls.read()
screen:clear()
screen:print(240,100,"Single Player",white)
screen:print(240,110,"Options",white)
screen:print(240,120,"Exit",white)
if current == 1 then
screen:print(240,100,"Single Player",red)
end
if current == 2 then
screen:print(240,110,"Options",red)
end
screen:print(240,120,"Exit",red)
end
if pad:up() and oldpad:up() ~= pad:up() then
current = current - 1
end
if pad:down() and oldpad:down() ~= pad:down() then
current = current + 1
end
if current == 6 then
current = 1
end
if current == 0 then
current = 5
end
screen.waitVblankStart()
screen.flip()
oldpad = pad
end

if pad:cross() and current == 1 then
Single = Player(
screen:clear()
)background = Image.load("images/background.jpg")
player2 = Image.load("images/player2.png")
end
if pad:cross() and current == 2 then
Options()
end
if pad:cross() and current == 3 then
Exit()
end

But when i press X in the menu, nothing happens, any help?
Oh and is there any tutorials on like making the screen scroll to see the rest of a map (like in Halo Genocide, if u keep moving right the screen will start to scroll)?

change you code to this:

--Colors
white = Color.new(255,255,255)
red = Color.new(255,0,0)
--Images
background = Image.load("images/background.jpg")
player2 = Image.load("images/player2.png")

current = 1 --this is our current menu selection
oldpad = Controls.read()
while true do
pad = Controls.read()
screen:clear()
screen:print(240,100,"Single Player",white)
screen:print(240,110,"Options",white)
screen:print(240,120,"Exit",white)
if current == 1 then
screen:print(240,100,"Single Player",red)
end
if current == 2 then
screen:print(240,110,"Options",red)
end
if current ==3 then
screen:print(240,120,"Exit",red)
end
if pad:up() and oldpad:up() ~= pad:up() then
current = current - 1
end
if pad:down() and oldpad:down() ~= pad:down() then
current = current + 1
end
if current == 6 then
current = 1
end
if current == 0 then
current = 5
end

if pad:cross() and current == 1 then
Single = Player(
screen:clear())
screen:blit(0,0,background)
screen:blit(0,0,player2)
end
if pad:cross() and current == 2 then
Options()
end
if pad:cross() and current == 3 then
Exit()
end

screen.waitVblankStart()
screen.flip()
oldpad = pad
end

[_-Tiger-_]

Hey thanks all. So does anyone know where i can find a tutorial on how to make the screen slid so to speak? For like sidescrolling games?

[Anti-QuickJay]

TacticalPenguin's code

playerimg = Image.load("player.png")
player = {x = 0, y = 272-playerimg:height()}
bgp1 = {x = 0, img = Image.load("bgp1.png") }
bgp2 = {x = 480, img = Image.load("bgp2.png") }
bgp3 = { x = 960, img = Image.load("bgp3.png") }
while true do
if player.x < 120 and bgp1.x < 0 then
bgp1.x = bgp1.x + 1
bgp2.x = bgp2.x + 1
bgp3.x = bgp3.x + 1
end
if player.x + playerimg:width() > 360 and bgp1.x > -960 then
bgp1.x = bgp1.x - 1
bgp2.x = bgp2.x - 1
bgp3.x = bgp3.x - 1
end
if pad:left() and player.x > 0 then player.x = player.x - 1 end
if pad:right() and player.x < 480-playerimg:width() then player.x = player.x + 1 end
screen:blit(bgp1.x,0,bgp1 .img)
screen:blit(bgp2.x,0,bgp2 .img)
screen:blit(bgp3.x,0,bgp3 .img)
screen:blit(player.x,play er.y,playerimg)
screen.waitVblankStart()
screen.flip()
end

[michaelp]

anyone ever seen this error?

libpng error: Too many IDAT's found

i have a feeling its from loading over 50 pngs but i thought i deleted them by setting them to nil. this does delete them correct?

when you set them to nil, try putting in this function after:

collectgarbage()

see here and here

[Anti-QuickJay]

function cleanUp()
image1 = nil
image2 = nil
image3 = nil
collectGarbage()
end

Then call the function when needed. It is slow though.

[Da_MerV]

ah, thanks to the both of ya

[Da_MerV]

Here's a function that uses the GU for a fast resizing/flipping of images:

function Gu.blit(x, y, image, scale, flip)
	
	if not scale or type(scale) == "string" then 
		flip = scale
		scale = 1
	end
	
	if flip then
		if flip == "H" then
			x_start = image:width()
			y_start = 0
			x_end  = 0
			y_end = image:height()
		elseif  flip == "V" then
			x_start = 0
			y_start = image:height()
			x_end  = image:width()
			y_end = 0
		elseif flip == "HV" then
			x_start = image:width()
			y_start = image:height()
			x_end = 0
			y_end = 0
		end
	else
		x_start = 0
		y_start = 0
		x_end = image:width()
		y_end = image:height()
	end
	
	width = (image:width()*scale)+x
	height = (image:height()*scale)+y
	temp = {
	{x_start, y_start, x, y, 0},
	{x_end, y_end, width, height, 0}
	}
	Gu.enable(Gu.TEXTURE_2D)
	Gu.texImage(image)
	Gum.drawArray(Gu.SPRITES, Gu.TEXTURE_32BITF+Gu.VERTEX_32BITF+Gu.TRANSFORM_2D, temp)
end

the argument "scale" is a multiplier for the size of the image, I.E. 0.5 is half size, 2 is double size, etc... If you leave this out the scale will default to 1

the argument "flip" is a string, "H" flips horizontally, "V" flips it vertically, "HV" will flip it both ways.

Because this uses the GU, you need to use Gu.start3d() and Gu.end3d(), also remember that you can't use the regular screen:blit function while the GU is running or lua player will crash.

and, here's an example script for how to use it:

img = Image.load("image.png")

pad = Controls.read()
screen:clear()
Gu.start3d() 
Gu.blit( 20,  20, img, 0.5, "H")
Gu.blit(100,  10, img, 1.5, "HV")
Gu.blit(300,  10, img, "V")
Gu.end3d() 
screen:flip()

while not pad:start() do
	pad = Controls.read()
end

To rotate an image to any angle, see this old post I made on Evilmana for an example:

http://www.forums.evilmana.com/index.php?topic=676.0

on the topic of image modification with the gu, would anyone know where to start in creating a gu model that could produce as effects as this:

exact numbers can be tweaked, just a general form.

[Merick]

Check this one out:

function RotateBlit(bx, by, bz, img, xrot, yrot, zrot, size) -- special blit function using the GU
--[[ 
bx, by, bz = x, y, and z coordinates to draw the image at
img = image to use
xrot,  yrot, zrot = rotation in degrees for each axis
size = size to display image in %, will default to 100% if left blank
]]
local w = img:width()/2
local h = img:height()/2

xrot = xrot * (Gu.PI/180)
yrot = yrot * (Gu.PI/180)
zrot = zrot * (Gu.PI/180)
   

if size == nil then size = 1
	else size = size / 100
end

local imagetile = {
	-- top section
	{ .5,  .5,   0,   0,  0},
	{  0,   0,  -w*size,   h*size,  0},
	{  1,   0,   w*size,   h*size,  0},
	-- right section
	{0.5, 0.5,   0,   0,  0},
	{  1,   0,   w*size,   h*size,  0},
	{  1,   1,   w*size,  -h*size,  0},
	-- bottom section
	{0.5, 0.5,   0,   0,  0},
	{  1,   1,   w*size,  -h*size,  0},
	{  0,   1,  -w*size,  -h*size,  0},
	-- left section
	{0.5, 0.5,   0,   0,  0},
	{  0,   1,  -w*size,  -h*size,  0},
	{  0,   0,  -w*size,   h*size,  0},   
	}


	Gu.enable(Gu.TEXTURE_2D);
	Gu.texImage(img)
	Gu.texFunc(Gu.TFX_MODULATE, Gu.TCC_RGBA)
	Gu.texFilter(Gu.NEAREST, Gu.NEAREST)
	Gu.texScale(1, 1)
	Gu.texOffset(0, 0)
	Gum.matrixMode(Gu.MODEL)
	Gum.loadIdentity()
	Gum.translate(bx, by, bz);
	Gum.rotateXYZ(xrot, yrot, zrot)
	Gum.drawArray(Gu.TRIANGLES, Gu.TEXTURE_32BITF+Gu.VERTEX_32BITF+Gu.TRANSFORM_3D, imagetile)
end

function start_gu(fov) -- starts the gu for drawing with the GuBlit function, 
--if you dont put anything in the () when calling this function the fov will default to 50

	if fov == nil then fov = 50 end
	Gu.start3d()
	Gu.clearDepth(0);
	Gu.clear(Gu.COLOR_BUFFER_BIT+Gu.DEPTH_BUFFER_BIT)
	Gum.matrixMode(Gu.PROJECTION)
	Gum.loadIdentity()
	Gum.perspective(fov, 480/272, 0.5, 1000)
	Gum.matrixMode(Gu.VIEW)
	Gum.loadIdentity()
	Gum.matrixMode(Gu.MODEL)
	Gum.loadIdentity()
	Gu.enable(Gu.BLEND)
	Gu.blendFunc(Gu.ADD, Gu.SRC_ALPHA, Gu.ONE_MINUS_SRC_ALPHA, 0, 0)
end

When used as-is these functions will let you blit a rotated image, but you might be able to alter them to do the other image transforms you wanted

example:

startSP() -- sets up the Gu for 3d

RotateBlit(0, 0, -290, image, 0,0,90, 150) -- blits an image rotated at 90 degrees in the center of the screen

Gu.end3d() -- stops the Gu

screen:flip()

Because this one uses perspective mode, any images blitted normally will always be underneath the images drawn with this function, anything drawn with fillRect or screenrint will be on top

Also, if used as-is this function will only work with images where the height and width are the same, and are multiples of 8

One last note - this is an old function that I gave up on a while ago, before mod 4 came out. Since mod 4 is supposed to have ortho mode implemented, if you can figure out how to use it instead of perspective mode you could probably fix the problems.

[Da_MerV]

how come the model is drawn with 4 triangles versus 2?

[Merick]

by drawing with 4 triangles, you can rotate it around the center of the image, if you were to draw it with 2 triangles the image would rotate around a corner, I've attached a crappy drawing to illustrate this

[Nielkie]

Does anyone know an easy way to draw a diagonal rectangle?

I mashed up this...

function round(num, idp)
	local mult = 10^(idp or 0)
	return math.floor(num * mult + 0.5) / mult
end

function diagline(x,y,width,height,angle)
	for i=0,height do
		local x0 = round(x - (i * math.cos((angle + 90)*math.pi/180)),0)
		local y0 = round(y - (i * math.sin((angle + 90)*math.pi/180)),0)

		Image:drawLine(
			x0,
			y0,
			round(x0 - (width * math.cos(angle*math.pi/180)),0),
			round(y0 - (width * math.sin(angle*math.pi/180)),0),
			grey
		)
	end
end

... but obviously it fragments up at certain angles, most noticeably at 45.

[Da_MerV]

You could try using the gu, seems its the hot topic of today.

Speaking of which, can anyone explain the different texture filters that I found in pspgu.h?
* - GU_NEAREST
* - GU_LINEAR
* - GU_NEAREST_MIPMAP_NEAREST
* - GU_LINEAR_MIPMAP_NEAREST
* - GU_NEAREST_MIPMAP_LINEAR
* - GU_LINEAR_MIPMAP_LINEAR
What are they, how do they work, what side effects do they have (ie. speed), and whats the result?

[Insert_Witty_Name]

You shouldn't need to change them from what Lua Player inits them to.

If you really must know, then Google for the OpenGL counterparts.

Merick: You don't need four triangles, you could do the same with two.

[Merick]

How? the only way that I can think of for doing it with only two triangles would require using extra calculations to create coordinate offsets which would need to rotate around the center of the image in the opposite direction of the image rotation...

[Insert_Witty_Name]

You just need to create the vertices for the outmost points, forget about the central point.

[KleptoOne]

You just need to create the vertices for the outmost points, forget about the central point.

Whenever I use that method it rotates around the corner point instead of the center, which is usually what I want, am I doing something wrong?

[Da_MerV]

i used triangle_strip and got it to run perfectly on 2 triangles. it also fixed the flicker problem.

[Insert_Witty_Name]

See attached image.

You need to translate to the centre point of where the image will be located, and plot your vertices around that central point.

Pseudo code:

drawRotatedRect(x, y, width, height, angle)
(
	halfWidth = width/2
	halfHeight = height/2

	createVert(x = -realWidth, y = -realHeight, 0)
	createVert(x = -realWidth, y = realHeight, 0)
	createVert(x = realWidth, y = realHeight, 0)
	createVert(x = realWidth, y = -realHeight, 0)
	
	loadIdentity()
	translate(x + halfWidth, y + halfHeight, 0)
	rotateZ(angle)
	
	draw(triangle_fan, verts)
)

I've used a triangle fan instead of two triangles, but you get the idea.

[drag_93]

I'm really stuck. I'm trying to create my own quiz game and everything works perfectly but I can't figure out a way to go the next question. The questions work on random numbers (as in a random number is made and the questions are shown accordingly to that random number e.g if random == 1 then) but after it says whether the answer is correct or not, it returns to the same question. Does anyone know how to fix this?

[SG57]

Post your code. For a quiz game, the general design should be something similar to having an array of structures/classes (in Lua, an array of tables). Within each structure/class members generally should be: question string, an array of answer strings and a variable saying which element in the answer array is the correct answer. Other members could include colors for each question or answer, a timer for each question so on more difficult questions they are given more time, X and Y coordinates for the question and answers to display, number of answers, etc. Then you assign a variable a random value ranging between how many elements in your question array.

Here's the general design of a quiz game I'd use. Implementing a time limit, different colors, etc. is made easy by this design. However, some designs may be made to run faster via sacrificing this ability Don't let this influence you to always use this sort of design, as there may be others out there that are better and the only way to find them is design your own.

math.randomseed(os.time());

NUM_QUESTIONS = 4
NUM_ANSWERS = 4

question = {}

question[1] = { name = "What is 2 + 2?", answer = {"X: 2","[]: 3","^: 4","O: 5"}, correctAnswer = 3 }
question[2] = { name = "What is SG57's real name?", answer = {"X: Jordan","[]: John","^: George","O: Bob"}, correctAnswer = 1 }
question[3] = { name = "How old is SG57?", answer = {"X: 12","[]: 13","^: 14","O: 15"}, correctAnswer = 4 }
question[4] = { name = "How long has SG57 been programming?", answer = {"X: ~1 year","[]: ~2 years","^: ~3 years","O: ~4 years"}, correctAnswer = 2 }

currentQuestion = math.random(1, NUM_QUESTIONS) -- does math.random generate a number including the smallest and biggest?  so 1 and 4 may be an output? if not, change thisto 0 and 5

correct = 0
incorrect = 0

oldQuestion = 0
oldpad = Controls.read()

function printCentered(y, STRING, color)
    screen:print( 240-string.len(STRING)/2*8, y, STRING, color)
end

while true do
    pad = Controls.read()

    if oldpad ~= pad then
        if pad:cross() then
            if question[currentQuestion].correctAnswer == 1 then
                correct = correct + 1
            else
                incorrect = incorrect + 1
            end
            
            oldQuestion = currentQuestion
            while currentQuestion == oldQuestion do
                currentQuestion = math.random(1,4)
            end
        elseif pad:square() then
            if question[currentQuestion].correctAnswer == 2 then
                correct = correct + 1
            else
                incorrect = incorrect + 1
            end
            
            oldQuestion = currentQuestion
            while currentQuestion == oldQuestion do
                currentQuestion = math.random(1,4)
            end
        elseif pad:triangle() then
            if question[currentQuestion].correctAnswer == 3 then
                correct = correct + 1
            else
                incorrect = incorrect + 1
            end
            
            oldQuestion = currentQuestion
            while currentQuestion == oldQuestion do
                currentQuestion = math.random(1,4)
            end
        elseif pad:circle() then
            if question[currentQuestion].correctAnswer == 4 then
                correct = correct + 1
            else
                incorrect = incorrect + 1
            end
            
            oldQuestion = currentQuestion
            while currentQuestion == oldQuestion do
                currentQuestion = math.random(1,4)
            end
        end
    end

    oldpad = pad

    screen:clear()

    printCentered(140,question[currentQuestion].name, Color.new(255,255,255))

    for i=1,NUM_ANSWERS do
        printCentered(160 + i*15,question[currentQuestion].answer[i], Color.new(200,200,200))
    end

    printCentered(10,"Correct:  " .. correct .. "                                 Incorrect:  " .. incorrect, Color.new(255,255,255))

    screen.waitVblankStart()
    screen.flip()
end

[slicer4ever]

make sure that ur calling recalling the random variable after the player has chosen the correct answer

[KleptoOne]

See attached image.

You need to translate to the centre point of where the image will be located, and plot your vertices around that central point.

Pseudo code:

drawRotatedRect(x, y, width, height, angle)
(
	halfWidth = width/2
	halfHeight = height/2

	createVert(x = -realWidth, y = -realHeight, 0)
	createVert(x = -realWidth, y = realHeight, 0)
	createVert(x = realWidth, y = realHeight, 0)
	createVert(x = realWidth, y = -realHeight, 0)
	
	loadIdentity()
	translate(x + halfWidth, y + halfHeight, 0)
	rotateZ(angle)
	
	draw(triangle_fan, verts)
)

I've used a triangle fan instead of two triangles, but you get the idea.

Thats so simple and makes perfect sense. Thanks for that, I'm still trying to get a handle on 3d designs, My background is in VBA apps so all these coordinates give me a headache sometimes.

[drag_93]

make sure that ur calling recalling the random variable after the player has chosen the correct answer

How do I do that?

[EminentJonFrost]

I'm really stuck. I'm trying to create my own quiz game and everything works perfectly but I can't figure out a way to go the next question. The questions work on random numbers (as in a random number is made and the questions are shown accordingly to that random number e.g if random == 1 then) but after it says whether the answer is correct or not, it returns to the same question. Does anyone know how to fix this?

you have to post some code up so someone can actually help you, or the most people can really do is throw examples at you like SG57 did.

and what slicer4ever means (correct me if i'm wrong!) is for the variable 'random' to change its value after the player answers the question correctly so that a new one appears, but i'm assuming thats in the case that a different question appears depending on the value of 'random'.

it would really help us help if you posted some code

[edit]an example i guess would be:

random = 1

if random == 1 then
-[post question]
--if question is answered then
--random = some other number
--end
elseif random == some other number then
-[post another question]
end

get it?