yg.gl

Functions and classes for GL drawing.

function yg.gl.draw()

Performs a GL draw call.

yg.gl.draw(geo, light, shader, texture, camera, trafo) -> void

Argument	Type	Info
`geo`	yg.gl.Geometry	Geometry to draw
`light`	yg.gl.Lightsource	Lightsource to apply. May be `nil`
`shader`	yg.gl.Shader	Shader to use
`texture`	yg.gl.Texture	Texture to use. May be `nil`
`camera`	yg.math.Camera	Camera to use. May be `nil`
`trafo`	yg.math.Trafo	Trafo to use as model trafo. May be `nil`

function yg.gl.drawSprite()

Draws a 2D sprite in screen space. Screen origin (x=0, y=0) in upper left corner.

Returns an array of 4 numbers (xmin, xmax, ymin, ymax) denoting the screen space axis aligned bounding box (AABB), the sprite is drawn in, as if it was not rotated.

The coords argument must be retrieved from texture to get valid coordinate information for a sprite from an atlas or grid texture. To draw an entire texture, yg.gl.Texture.getGridCoords(1, 1, 0) can be used. See example:

-- Example for yg.gl.drawSprite()
function init()
    yg.asset.loadTexture("demo", "a//demo.png", "",
                         "DIFFUSE", "LINEAR", "REPEAT", true)
    -- Get coords for the entire texture, to draw it with drawSprite()
    coordsDemo = yg.asset.getTexture("demo"):getGridCoords(1, 1, 0)
end

function tick()
    -- Use screenPos to detect clicks or collisions
    screenPos = yg.gl.drawSprite(yg.asset.getTexture("demo"),
                                 coordsDemo, 400, 300, 250, 0, 0)
end

yg.gl.drawSprite(texture, coords, x, y, width, height, angle) -> {number}

Argument	Type	Info
`texture`	yg.gl.Texture	Texture to draw from
`coords`	yg.gl.TextureCoords	Subtexture coordinate info to pick sprite from atlas/grid
`x`	number	X-position (center of sprite)
`y`	number	Y-position (center of sprite)
`width`	number	Width of sprite [pixels]. If `0.0`, width is determined from original sprite size
`height`	number	Height of sprite [pixels]. If `0.0`, height is determined from original sprite size
`angle`	number	Counter-clockwise rotation of sprite [rad]

function yg.gl.drawSky()

Draws sky from image texture.

yg.gl.drawSky(texture, camera, tint, trafo) -> void

Argument	Type	Info
`texture`	yg.gl.Texture	Sky texture
`camera`	yg.math.Camera	Camera to use
`tint`	{number}	Tint, ends up as ambient color in shader. Default (neutral): `{1,1,1}` (array of 3 numbers)
`trafo`	yg.math.Trafo	Rotation of `trafo` is applied to sky. May be `nil`

function yg.gl.depthTest()

Enables/disables depth test via glEnable(GL_DEPTH_TEST) / glDisable(GL_DEPTH_TEST).

yg.gl.depthTest(enable) -> void

Argument	Type	Info
`enable`	boolean	Options: `true`: enable, `false`: disable

function yg.gl.clearColor()

Sets the clear color via glClearColor().

yg.gl.clearColor(r, g, b, a) -> void

Argument	Type	Info
`r`	number	Red
`g`	number	Green
`b`	number	Blue
`a`	number	Alpha

class yg.gl.Texture

function yg.gl.Texture.getCoords()

Returns coordinate information of a sprite called name. Typically used with textures loaded together with an atlas file, see yg.asset.loadTexture(). See also Accessing Sprites and Sequences in the Manual.

yg.gl.Texture.getCoords(name) -> yg.gl.TextureCoords

Argument	Type	Info
`name`	string	Name of the sprite

function yg.gl.Texture.getFrameCoords()

Returns coordinate information of a sprite which is a frame of a sequence. frame is always wrapped into valid range and may be negative. Typically used with textures loaded together with an atlas file, see yg.asset.loadTexture(). See also Accessing Sprites and Sequences in the Manual.

yg.gl.Texture.getFrameCoords(sequenceName, frame) -> yg.gl.TextureCoords

Argument	Type	Info
`sequenceName`	string	Name of the sprite sequence
`frame`	number	Frame index

function yg.gl.Texture.getGridCoords()

Returns texture coordinates of a grid cell. Any grid size can be used for any texture. To get coordinates for the entire texture, call yg.gl.Texture.getGridCoords(1, 1, 0).

yg.gl.Texture.getGridCoords(gridWidth, gridHeight, index) -> yg.gl.TextureCoords

Argument	Type	Info
`gridWidth`	number	Number of grid columns
`gridHeight`	number	Number of grid rows
`index`	number	Index of the grid cell to return coordinates for, starting top-left with index `0`

class yg.gl.Lightsource

Represents a lightsource.

constructor

yg.gl.Lightsource() -> yg.gl.Lightsource

function yg.gl.lightsource.setAmbient()

Sets ambient light component.

yg.gl.lightsource.setAmbient(r, g, b) -> void

Argument	Type	Info
`r`	number	Red light component
`g`	number	Green light component
`b`	number	Blue light component

function yg.gl.lightsource.setDiffuse()

Sets diffuse light component.

yg.gl.lightsource.setDiffuse(r, g, b) -> void

Argument	Type	Info
`r`	number	Red light component
`g`	number	Green light component
`b`	number	Blue light component

function yg.gl.lightsource.setSpecular()

Sets specular light component.

yg.gl.lightsource.setSpecular(r, g, b) -> void

Argument	Type	Info
`r`	number	Red light component
`g`	number	Green light component
`b`	number	Blue light component

function yg.gl.lightsource.setPosition()

Sets light origin in world.

yg.gl.lightsource.setPosition(r, g, b) -> void

Argument	Type	Info
`x`	number	X coordinate
`y`	number	Y coordinate
`z`	number	Z coordinate

class yg.gl.Geometry

No functionality accessible. Used to pass around instances, like from yg.asset.getGeometry() to yg.gl.draw().

class yg.gl.Shader

No functionality accessible. Used to pass around instances, like from yg.asset.getShader() to yg.gl.draw().

class yg.gl.TextureCoords

No functionality accessible. Used to pass around instances, like from yg.gl.Texture.getCoords() to yg.gl.drawSprite().