glok-core/uk.co.nickthecoder.glok.backend.webgl/WebGLBackend

WebGLBackend

The backend rendering code for the web (i.e. in a web browser). Unlike the JVM backend (GLBackend), the WebGLBackend only support a single instance of Window, which uses a html canvas.

Major difference between WebGL and a regular GL frame buffer :

A WebGL canvas has transparency by default
A WebGL canvas uses pre-multiplied alphas

I really don't want to deal with pre-multiplied alphas, so I've turned this off.

I've read that turning off alpha gives large a performance hit, so I've left it on. Instead, within clear, we ensure the fill color is fully opaque and then turn off the alpha channel with a color mask. I don't know if this is any quicker than turning off alpha completely.

Constructors

WebGLBackend

constructor()

Types

Companion

object Companion

Functions

batch

open override 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

open override 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

open override fun clear(color: Color)

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

clearTransform

open override fun clearTransform()

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

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

Creates a texture filled with the given color.

open override fun createTexture(name: String, width: Int, height: Int, color: Color): Texture

Creates a texture filled with the given color.

createWindow

open override fun createWindow(width: Int, height: Int): Window

This must be called only once (i.e. only 1 window is allowed when using the WebGLBackend).

drawFrame

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

drawTexture

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

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

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

drawView

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

endClipping

open override fun endClipping()

fileResources

open override fun fileResources(path: String): Resources

In a JVM context, path is the path of a file (which may be a relative path). The textures are loaded immediately (unlike in a JS context, where there will be a delay).

fillCircle

open override fun fillCircle(centerX: Float, centerY: Float, radius: Float, color: Color)

fillQuarterCircle

open override fun fillQuarterCircle(centerX: Float, centerY: Float, cornerX: Float, cornerY: Float, color: Color, radius: Float)

fillRect

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

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

gradient

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

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

hsvGradient

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

monitorSize

open override fun monitorSize(): Pair<Int, Int>

noClipping

open override fun noClipping(block: () -> Unit)

pollEvents

open override fun pollEvents(timeoutSeconds: Double)

reportError

open fun reportError(): Boolean

resources

open override fun resources(path: String, klass: KClass<*>?): Resources

For built-in resources. The textures from Resources.loadTexture will be available immediately.

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.

setMousePointer

open override fun setMousePointer(window: Window, cursor: MousePointer)

strokeCircle

open override fun strokeCircle(centerX: Float, centerY: Float, radius: Float, innerRadius: Float, color: Color)

strokeInsideRect

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

open fun strokeInsideRect(rect: GlokRect, insideRect: GlokRect, color: Color)

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

open override fun strokeInsideRect(left: Float, top: Float, right: Float, bottom: Float, insideLeft: Float, insideTop: Float, insideRight: Float, insideBottom: Float, color: Color)

strokeQuarterCircle

open override fun strokeQuarterCircle(centerX: Float, centerY: Float, cornerX: Float, cornerY: Float, color: Color, radius: Float, innerRadius: Float)

transform

open override fun transform(transformation: Matrix)

open override 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.