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Add coordinates expressions in WebGL tiles #15478

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Add coordinates expressions in WebGL tiles #15478

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e3c5567
Add coordinates expressions in WebGL tiles
Jan 10, 2024
634958d
Change new line characters to LF instead of CRLF
Jan 11, 2024
f8eb852
Merge branch 'openlayers:main' into main
Dolpic Jan 13, 2024
f3a74a8
Merge branch 'openlayers:main' into main
Dolpic May 21, 2024
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58 changes: 51 additions & 7 deletions examples/webgl-shaded-relief.js
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Expand Up @@ -28,15 +28,58 @@ function elevation(xOffset, yOffset) {
];
}

// Edges conditions to avoid computations with pixels ouside the current tile.
const isLeftEdge = ['<=', ['tileCoordX'], 1];
const isRightEdge = ['>=', ['tileCoordX'], ['-', ['tileMaxCoordX'], 1]];
const isTopEdge = ['<=', ['tileCoordY'], 1];
const isBottomEdge = ['>=', ['tileCoordY'], ['-', ['tileMaxCoordY'], 1]];

// Computes the vertical and horizontal values for slope and aspect.
// Avoid computation with pixels outside the current tile.
const dpx = [
'case',
['any', isLeftEdge, isRightEdge],
['*', 1, ['resolution']],
['*', 2, ['resolution']],
];

const dpy = [
'case',
['any', isTopEdge, isBottomEdge],
['*', 1, ['resolution']],
['*', 2, ['resolution']],
];

const z0x = [
'case',
isLeftEdge,
['*', ['var', 'vert'], elevation(0, 0)],
['*', ['var', 'vert'], elevation(-1, 0)],
];
const z1x = [
'case',
isRightEdge,
['*', ['var', 'vert'], elevation(0, 0)],
['*', ['var', 'vert'], elevation(1, 0)],
];

const z0y = [
'case',
isTopEdge,
['*', ['var', 'vert'], elevation(0, 0)],
['*', ['var', 'vert'], elevation(0, -1)],
];
const z1y = [
'case',
isBottomEdge,
['*', ['var', 'vert'], elevation(0, 0)],
['*', ['var', 'vert'], elevation(0, 1)],
];

// Generates a shaded relief image given elevation data. Uses a 3x3
// neighborhood for determining slope and aspect.
const dp = ['*', 2, ['resolution']];
const z0x = ['*', ['var', 'vert'], elevation(-1, 0)];
const z1x = ['*', ['var', 'vert'], elevation(1, 0)];
const dzdx = ['/', ['-', z1x, z0x], dp];
const z0y = ['*', ['var', 'vert'], elevation(0, -1)];
const z1y = ['*', ['var', 'vert'], elevation(0, 1)];
const dzdy = ['/', ['-', z1y, z0y], dp];
const dzdx = ['/', ['-', z1x, z0x], dpx];
const dzdy = ['/', ['-', z1y, z0y], dpy];
const slope = ['atan', ['sqrt', ['+', ['^', dzdx, 2], ['^', dzdy, 2]]]];
const aspect = ['clamp', ['atan', ['-', 0, dzdx], dzdy], -Math.PI, Math.PI];
const sunEl = ['*', Math.PI / 180, ['var', 'sunEl']];
Expand All @@ -54,6 +97,7 @@ const shadedRelief = new TileLayer({
source: new XYZ({
url: 'https://s3.amazonaws.com/elevation-tiles-prod/terrarium/{z}/{x}/{y}.png',
maxZoom: 15,
interpolate: false, // Enabling interpolation may create artifacts between tiles.
attributions:
'<a href="https://github.com/tilezen/joerd/blob/master/docs/attribution.md" target="_blank">Data sources and attribution</a>',
}),
Expand Down
8 changes: 8 additions & 0 deletions src/ol/expr/expression.js
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Expand Up @@ -352,6 +352,10 @@ export const Ops = {
Resolution: 'resolution',
Zoom: 'zoom',
Time: 'time',
TileCoordX: 'tileCoordX',
TileCoordY: 'tileCoordY',
TileMaxCoordX: 'tileMaxCoordX',
TileMaxCoordY: 'tileMaxCoordY',
Equal: '==',
NotEqual: '!=',
GreaterThan: '>',
Expand Down Expand Up @@ -427,6 +431,10 @@ const parsers = {
[Ops.Resolution]: createParser(NumberType, withNoArgs),
[Ops.Zoom]: createParser(NumberType, withNoArgs),
[Ops.Time]: createParser(NumberType, withNoArgs),
[Ops.TileCoordX]: createParser(NumberType, withNoArgs),
[Ops.TileCoordY]: createParser(NumberType, withNoArgs),
[Ops.TileMaxCoordX]: createParser(NumberType, withNoArgs),
[Ops.TileMaxCoordY]: createParser(NumberType, withNoArgs),
[Ops.Any]: createParser(
BooleanType,
withArgsCount(2, Infinity),
Expand Down
4 changes: 4 additions & 0 deletions src/ol/expr/gpu.js
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Expand Up @@ -273,6 +273,10 @@ const compilers = {
[Ops.Resolution]: () => 'u_resolution',
[Ops.Zoom]: () => 'u_zoom',
[Ops.Time]: () => 'u_time',
[Ops.TileCoordX]: () => 'v_textureCoord.x * u_texturePixelWidth',
[Ops.TileCoordY]: () => 'v_textureCoord.y * u_texturePixelHeight',
[Ops.TileMaxCoordX]: () => 'u_texturePixelWidth',
[Ops.TileMaxCoordY]: () => 'u_texturePixelHeight',
[Ops.Any]: createCompiler((compiledArgs) => `(${compiledArgs.join(` || `)})`),
[Ops.All]: createCompiler((compiledArgs) => `(${compiledArgs.join(` && `)})`),
[Ops.Not]: createCompiler(([value]) => `(!${value})`),
Expand Down