WorldWind Kotlin/earth.worldwind.draw/DrawableViewshedKernel

DrawableViewshedKernel

open class DrawableViewshedKernel : Drawable

Single-pass GPU dispatch for earth.worldwind.shape.ViewshedSightline's visibility kernel. Uploads the elevation grid as R32F, runs the per-fragment Amanatides–Woo walk via ViewshedKernelShaderProgram into an externally-owned RGBA8 outputTexture, and signals completion via callback. The texture lives on the GPU and is sampled directly by SurfaceImage on its own draw — no CPU readback, no PBO, no fence.

NOT pool-managed; the renderable holds a single instance and re-enqueues it per dispatch. recycle is a deliberate no-op. width/height are settable per-dispatch — the same drawable instance survives samplesPerSide changes; only the outputTexture reference is swapped out by the renderable.

Bails (no callback fired) when Kgl.supportsSizedTextureFormats is false (WebGL1 / GLES2); the kernel needs R32F and texelFetch.

Constructors

DrawableViewshedKernel

constructor()

Types

Companion

object Companion

Properties

areaHalfPxX

var areaHalfPxX: Float

areaHalfPxY

var areaHalfPxY: Float

areaMode

var areaMode: Int

0 = circular AOI, 1 = rectangular AOI.

callback

var callback: () -> Unit?

Invoked on the GL thread once the kernel has rendered into outputTexture.

disposeOnNextDraw

var disposeOnNextDraw: Boolean

If true, draw drains texturesToRelease, calls release on this drawable's own GPU resources, and returns without rendering. The renderable sets this from dispose(); one final enqueue gets all resources off the GL.

earthRadius

var earthRadius: Float

elevations

var elevations: FloatArray?

Source elevations in row-major south-up order (matching Globe.getElevationGrid).

height

var height: Int

metersPerPixelX

var metersPerPixelX: Float

metersPerPixelY

var metersPerPixelY: Float

missingValue

var missingValue: Float

observerAltitude

var observerAltitude: Float

observerCellX

var observerCellX: Int

observerCellY

var observerCellY: Int

occludedColor

val occludedColor: Color

outputTexture

var outputTexture: Texture?

RGBA8 render target attached to GL_COLOR_ATTACHMENT0. Owned by the renderable.

program

var program: ViewshedKernelShaderProgram?

Shader program acquired via RenderContext.getShaderProgram before enqueue.

texturesToRelease

val texturesToRelease: MutableList<Texture>

Textures the renderable wants released on the next draw. Used to dispose previous outputTexture instances after a samplesPerSide change without leaking until engine teardown. Drained at the top of draw.

verticalExaggeration

var verticalExaggeration: Float

visibleColor

val visibleColor: Color

width

var width: Int

Functions

draw

open override fun draw(dc: DrawContext)

recycle

open override fun recycle()

release

fun release(dc: DrawContext)

Free this drawable's GPU resources. Must run on the GL thread (i.e. from within draw).