Struct WorldToScreen

Namespace

EncDotNet.S100.Rendering.Scene

Assembly

EncDotNet.S100.Rendering.Scene.dll

A linear EPSG:3857-world → screen-pixel affine derived from a Viewport — the second half of the S-100 Part 9 projection (EPSG:3857 → screen pixels) that a PaintOp deliberately leaves to each rendering backend (see the unit contract on PaintOp).

public readonly struct WorldToScreen

Inherited Members

ValueType.Equals(object)

ValueType.GetHashCode()

ValueType.ToString()

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Remarks

The viewport's geographic bounds are projected to EPSG:3857 via FromLonLat(double, double) and mapped linearly to the pixel rectangle with origin top-left and screen-space +Y pointing down (northing decreases downward). The transform is north-up only — it applies no rotation.

This helper is intentionally framework-neutral (it depends only on Viewport and WebMercator), so a rendering backend that does not use SkiaSharp or Mapsui can project the world coordinates carried on each PaintOp to output pixels without taking a dependency on either backend. It provides only the geometry (world → pixel) projection; size values on the IR are already in display pixels and must not be passed through this transform.

Methods

Create(Viewport)

Builds the world → screen affine for the supplied viewport. The viewport's geographic corners are projected to EPSG:3857 and mapped to the [0, WidthPixels] × [0, HeightPixels] pixel rectangle. A viewport with a zero-width or zero-height projected span yields a zero scale on that axis (all coordinates collapse to the axis origin).

public static WorldToScreen Create(Viewport viewport)

Parameters

viewport Viewport

The display viewport (geographic bounds + pixel size).

Returns

WorldToScreen

The world → screen affine.

Remarks

When the viewport is expressed in a longitude frame shifted across the ±180° antimeridian (MaxLongitude > 180 or MinLongitude < −180, as produced by the seam-aware auto-fit — see SeamAwareBoundsAccumulator), each op's world-X is wrapped into [minX, minX + Circumference) before projection so geometry on the far side of the seam registers in the shifted window. For every normal viewport (which never exceeds ±180°) wrapping is disabled, so partially off-screen features are never teleported. Wrapping is also disabled for a viewport spanning a full world or more of longitude, where every op already lies inside the window unwrapped.

Create(Viewport, bool)

As Create(Viewport), but with control over whether the antimeridian seam-wrap is applied. When allowSeamWrap is false, world-X is never wrapped into the viewport's longitude window even if the viewport is shifted across ±180°. The tiled renderer passes false because it draws already-continuous geometry from narrow per-tile viewports, where wrapping would smear polygons that extend beyond a single tile (see the flag's remarks on the tiled renderer).

public static WorldToScreen Create(Viewport viewport, bool allowSeamWrap)

Parameters

viewport Viewport

The display viewport (geographic bounds + pixel size).

allowSeamWrap bool

true to wrap world-X into a viewport shifted across the ±180° seam (headless auto-fit); false to disable wrapping (tiled continuous-X rasterisation).

Returns

WorldToScreen

The world → screen affine.

Project((double X, double Y))

Projects an EPSG:3857 world coordinate to a screen pixel (origin top-left, +Y down).

public (float X, float Y) Project((double X, double Y) world)

Parameters

world (double X, double Y)

The world coordinate in EPSG:3857 metres.

Returns

(float X, float Y)

The screen pixel coordinate.