glok-core/uk.co.nickthecoder.glok.backend/Backend

Backend

All drawing operations are done from here. By having this as an interface, this lets us have different backends, which leaves open the possibility of creating a multi-platform kotlin project with a different Backend for the js platform for use in a browser.

NOTE. LoggingBackend doesn't draw anything, but lets us create test cases without setting up an OpenGL.

Inheritors

DummyBackend

LoggingBackend

WebGLBackend

Types

Companion

object Companion

Functions

batch

abstract fun batch(texture: Texture, tint: Color?, modelMatrix: Matrix?, block: TextureBatch.() -> Unit)

OpenGL is moe efficient when operations can be batched. So rather than call drawTexture multiple times (with the same texture, tint, and modelMatrix), batch them and call TextureBatch.draw instead.

beginClipping

abstract fun beginClipping(left: Float, top: Float, width: Float, height: Float): Boolean

Clip (scissor). The values are LogicalPixels measured from the TOP left of the window. The clipped region is the intersection of the currently clipped region and the newly requested region.

clear

abstract fun clear(color: Color)

Draws a flot color over the entire viewport. Used at the start of each redraw.

clip

open fun clip(left: Float, top: Float, width: Float, height: Float, block: () -> Unit)

A convenient way to call beginClipping and endClipping, with a block of code in between.

open fun clip(clip: Boolean, left: Float, top: Float, width: Float, height: Float, block: () -> Unit)

createTexture

abstract fun createTexture(name: String, width: Int, height: Int, pixels: IntArray): Texture

createWindow

abstract fun createWindow(width: Int, height: Int): Window

drawFrame

abstract fun drawFrame(window: Window, block: () -> Unit)

drawTexture

abstract fun drawTexture(texture: Texture, srcX: Float, srcY: Float, width: Float, height: Float, destX: Float, destY: Float, destWidth: Float = width, destHeight: Float = height, modelMatrix: Matrix? = null)

Draws the part of the texture defined by the rectangle srcX, srcY, height to destX, destY (which is where the top-left of the source corresponds to).

drawTintedTexture

abstract fun drawTintedTexture(texture: Texture, tint: Color, srcX: Float, srcY: Float, width: Float, height: Float, destX: Float, destY: Float, destWidth: Float = width, destHeight: Float = height, modelMatrix: Matrix? = null)

drawView

abstract fun drawView(width: Float, height: Float, scale: Float, block: () -> Unit)

endClipping

abstract fun endClipping()

fillQuarterCircle

abstract fun fillQuarterCircle(x1: Float, y1: Float, x2: Float, y2: Float, color: Color, radius: Float)

fillRect

abstract fun fillRect(rect: GlokRect, color: Color)

abstract fun fillRect(left: Float, top: Float, right: Float, bottom: Float, color: Color)

gradient

abstract fun gradient(triangles: FloatArray, colors: Array<Color>)

A gradient fill. Each vertex of each triangle has a color.

hsvGradient

abstract fun hsvGradient(triangles: FloatArray, colors: Array<FloatArray>)

monitorSize

abstract fun monitorSize(): Pair<Int, Int>?

processEvents

abstract fun processEvents(timeoutSeconds: Double)

reportError

open fun reportError(): Boolean

resources

abstract fun resources(path: String): Resources

saveRestoreState

open fun saveRestoreState(block: () -> Unit)

If you need to use OpenGL while Glok is rendering a scene, you must perform these actions within a block. This saves the OpenGL state, runs the block, and then restores the state again.

setCursor

abstract fun setCursor(window: Window, cursor: StandardCursor)

strokeInsideRect

abstract fun strokeInsideRect(rect: GlokRect, thickness: Float, color: Color)

abstract fun strokeInsideRect(left: Float, top: Float, right: Float, bottom: Float, thickness: Float, color: Color)

strokeQuarterCircle

abstract fun strokeQuarterCircle(x1: Float, y1: Float, x2: Float, y2: Float, color: Color, radius: Float, innerRadius: Float)

transform

abstract fun transform(transformation: Matrix, block: () -> Unit)

Transforms the coordinates of all drawing calls within the block of code. Used by the Rotation node and ProxyNode.