Lua documentation

Basics

Everytime engine is launched, it will load logic.lua file in scripts folder. This is how logic.lua should look like at its simplest form:

-- Called when network response is available.
function eventResponse(response)

end

-- Called when GUI component listeners are activated.
function eventGUI(guiNode, eventType)

end

-- Handle initialization.
function start()

end

-- Called when program is brought to foreground.
function resume()

end

-- Called when program screen resolution is changed.
function resize()

end

-- Called every frame.
function update()

end

-- Called when program is brought to background.
function pause()

end

-- Called when program is about to quit.
function quit()

end

General functions

print(text) -- used for printing text
pointerIsOver(node) -- returns true if mouse or other pointer is over specific node
playSound("file.mp3", true) -- plays sound file. Second parameter indicates 
loadScene("scene.lua") -- loads specified lua scene file
exit() -- closes program
getScreenWidth() -- returns screen width in pixels
getScreenHeight() -- returns screen height in pixels
getTimeDelta() -- returns elapsed time in milliseconds

Camera controls

Moving along camera directions and looking around

function update()
	camera = getCamera()
	input = getInput()

	local offset = 0.1
	if input:keyPressed(constants["W"]) then
		camera:moveZ(-offset)
	end
	if input:keyPressed(constants["S"]) then
		camera:moveZ(offset)
	end
	if input:keyPressed(constants["A"]) then
		camera:moveX(-offset)
	end
	if input:keyPressed(constants["D"]) then
		camera:moveX(offset)
	end

	camera:addRotX(input:getPointerDeltaY() * 0.2)
	camera:addRotY(input:getPointerDeltaX() * 0.2)
end

Working with nodes

Every object in the scene belongs to a Node object. As a result all of these methods can be called on each object:

node = getNode("resource name") -- node and it's corresponding resource share same name
node:setParent(parentNode)
node:addChild(childNode)
node:enablePhysics(massInKg) -- enables physics. Can be used only on Model resources
node:disablePhysics()
node:setMass(99.9) -- sets physics mass in kg
node:accelerate(0.0, 100.0, 0.0) -- accelerates physics object in specified vector direction and speed
node:setBool("paramName", true) -- sets attribute for underlying resource
node:setInt("paramName", 5) -- sets attribute for underlying resource
node:setFloat("paramName", 5.5) -- sets attribute for underlying resource
node:setString("paramName", "paramValue") -- sets attribute for underlying resource
node:setShader(shaderObject) -- sets shader. Applies to model, GUISurface and sprite.
shader = node:getShader(shaderObject) -- returns shader used by resource
node:setTexture(textureObject) -- applies to model or sprite only.
node:setIndex(spriteIndex) -- allows to specify animation frame for animated sprite resources.
node:getCount() -- returns number of frames in sprite resources.
node:getName() -- returns node name
node:setVisibility(true) -- sets visibility flag to indicate whether node should be rendered
isNodeVisible = node:getVisibility() -- returns visibility flag
node:setFontSize(16) -- sets text size for Text and Button nodes
node:setText("hello world") -- sets text for Text and Button nodes
node:setColor("#FFFFFFFF") -- sets text color for Text and Button nodes. Format - ARGB
node:setBackground("#FF000000") -- sets background for any GUISurface (Button, Text)
node:setBackgroundSelected("#FF000000") -- sets color for selected background. Applies to Button
node:setBackground(textureObject) -- sets background texture for any GUISurface (Button, Text)
backgroundColor = node:getBackground() -- returns background color of GUISurface
nodeWidth = node:getWidth() -- returns width, same as node:getScaleX()
nodeHeight = node:getHeight() -- returns height, same as node:getScaleY()
node:setWidth(500) -- sets node width. Same as node:setScaleX(500)
node:setHeight(500) -- sets node height. Same as node:setScaleY(500)
node:setAmbient("#FFFFFFFF") -- sets ambient color. Applies to model resources only.
node:setDiffuse("#FFFFFFFF") -- sets diffuse color. Applies to model resources only.
node:setSpecular("#FFFFFFFF") -- sets specular color. Applies to model resources only.
node:setType("mesh") -- sets model type(mesh|shape|plane|sphere|terrain|water). Applies to model resources only.
node:moveX(100.0) -- move node on it's direction X axis
node:moveY(100.0) -- move node on it's direction Y axis
node:moveZ(100.0) -- move node on it's direction Z axis
node:moveViewCameraDirection(100.0) -- move node in camera look at direction.
node:(add|set|get)(Pos|Scale|Rot)(X|Y|Z)(100) -- use any combination of method parts to construct required call. XYZ can be combined together, or in parts of XY, YZ, XZ.

Working with 2D models

Loading simple sprite with texture

texture = Texture.new("texture.png")
sprite = Sprite.new("Sprite name")
sprite:setWidth(200);
sprite:setHeight(200);
sprite:setPosX(300)
sprite:setPosY(300)
sprite:setTexture(texture)

Loading simple text

text = Text.new("text name")
text:setText("Hello world")
text:setColor("#CC0000FF")
text:setPosX(200) -- Position from left
text:setPosY(50) -- Position from top
text:setFontSize(46)
text:setBackground("#000000FF")
text:setVisibility(true)

Working with 3D models

Loading simple plane with texture

plane = Model.new("model_name")
plane:setType("plane")
plane:setAmbient("#FFFFFFFF")
plane:setShader(Shader.new("shader_file_name"))
plane:setTexture(Texture.new("texture_file.png"))
plane:setPosY(-2.0)
plane:setScaleXYZ(100.0, 100.0, 100.0)

Enabling physics

Physics only work for nodes with Model resource. Call enablePhysics() after setting model type and other attributes.

node:setType("plane")
node:setScaleXYZ(10.0, 1.0, 3.0)
node:enablePhysics()

Working with shaders

List of available parameters:

#define SHADER_MAIN_TEXTURE "mainTexture"
#define SHADER_HAS_MAIN_TEXTURE "uMainTexture"
#define SHADER_VERTEX_SUFFIX ".vert"
#define SHADER_FRAGMENT_SUFFIX ".frag"
#define SHADER_WVP "uWVP"
#define SHADER_W "uW"
#define SHADER_N "uN"
#define SHADER_COLOR_BUFFER "colorBuffer"
#define SHADER_DEPTH_BUFFER "depthBuffer"
#define SHADER_SCREEN_WIDTH "uScreenWidth"
#define SHADER_SCREEN_HEIGHT "uScreenHeight"
#define SHADER_LIGHT_POS "uLightPos"
#define SHADER_LIGHT_COUNT "uLightCount"
#define SHADER_EYE_POS "uEyePos"
#define SHADER_AMBIENT "uAmbient"
#define SHADER_DIFFUSE "uDiffuse"
#define SHADER_SPECULAR "uSpecular"
#define SHADER_SPEC_INTENSITY "uSpecIntensity"
#define SHADER_TRANSPARENCY "uTransparency"
#define SHADER_FOG_COLOR "uFogColor"
#define SHADER_FOG_DENSITY "uFogDensity"
#define SHADER_TIMER "uTimer"
#define SHADER_POS "attrPos"
#define SHADER_NORMAL "attrNorm"
#define SHADER_UV "attrUV"
#define SHADER_COL "attrCol"
#define SHADER_FOREGROUND "uForeground"
#define SHADER_BACKGROUND "uBackground"
#define SHADER_TEXTURE_2D "texture_"
#define SHADER_CUBE_MAP "cubeMap_0"

Samples

FPS counter

function start()
	print("Called start()")
	input = getInput()
    print("Screen width in lua: " .. getScreenWidth() .. ", height: " .. getScreenHeight())
    fpsCounter = Button.new("fpsCounter")
    fpsCounter:setColor("#FFFF00FF")
    fpsCounter:setBackground("#33333333")
    fontSize = 14
    fpsCounter:setFontSize(14)
    fpsCounter:setWidth(1256)
    fpsCounter:setHeight(64)
    fpsCount = 0
    fpsTime = 0
end

function resume()
	print("Called resume()")
end

function resize()
	print("Called resize()")
end

function update()
    fpsTime = fpsTime + getTimeDelta()
    if fpsTime >= 1000 then
        fpsCounter:setText("FPS: " .. fpsCount .. "\nResolution: " .. getScreenWidth() .. "x" .. getScreenHeight() .. "px")
        fpsCount = 0
        fpsTime = 0
    end
end