@deck.gl/core/src/lib/picking/query-object.ts

deck.gl core library

// deck.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

import log from '../../utils/log';
import type Layer from '../layer';
import type Viewport from '../../viewports/viewport';
import type {PickingColorDecoder} from '../../passes/pick-layers-pass';

export type PickedPixel = {
  pickedColor: Uint8Array | null;
  pickedLayer?: Layer;
  pickedViewports?: Viewport[];
  pickedX?: number;
  pickedY?: number;
  pickedObjectIndex: number;
};

const NO_PICKED_OBJECT = {
  pickedColor: null,
  pickedObjectIndex: -1
};

/* eslint-disable max-depth, max-statements */
/**
 * Pick at a specified pixel with a tolerance radius
 * Returns the closest object to the pixel in shape `{pickedColor, pickedLayer, pickedObjectIndex}`
 */
export function getClosestObject({
  pickedColors,
  decodePickingColor,
  deviceX,
  deviceY,
  deviceRadius,
  deviceRect
}: {
  pickedColors: Uint8Array;
  decodePickingColor: PickingColorDecoder;
  deviceX: number;
  deviceY: number;
  deviceRadius: number;
  deviceRect: {x: number; y: number; width: number; height: number};
}): PickedPixel {
  // Traverse all pixels in picking results and find the one closest to the supplied
  // [deviceX, deviceY]
  const {x, y, width, height} = deviceRect;
  let minSquareDistanceToCenter = deviceRadius * deviceRadius;
  let closestPixelIndex = -1;
  let i = 0;

  for (let row = 0; row < height; row++) {
    const dy = row + y - deviceY;
    const dy2 = dy * dy;

    if (dy2 > minSquareDistanceToCenter) {
      // skip this row
      i += 4 * width;
    } else {
      for (let col = 0; col < width; col++) {
        // Decode picked layer from color
        const pickedLayerIndex = pickedColors[i + 3] - 1;

        if (pickedLayerIndex >= 0) {
          const dx = col + x - deviceX;
          const d2 = dx * dx + dy2;

          if (d2 <= minSquareDistanceToCenter) {
            minSquareDistanceToCenter = d2;
            closestPixelIndex = i;
          }
        }
        i += 4;
      }
    }
  }

  if (closestPixelIndex >= 0) {
    // Decode picked object index from color
    const pickedColor = pickedColors.slice(closestPixelIndex, closestPixelIndex + 4);
    const pickedObject = decodePickingColor(pickedColor);
    if (pickedObject) {
      const dy = Math.floor(closestPixelIndex / 4 / width);
      const dx = closestPixelIndex / 4 - dy * width;
      return {
        ...pickedObject,
        pickedColor,
        pickedX: x + dx,
        pickedY: y + dy
      };
    }
    log.error('Picked non-existent layer. Is picking buffer corrupt?')();
  }
  return NO_PICKED_OBJECT;
}

/**
 * Examines a picking buffer for unique colors
 * Returns array of unique objects in shape `{x, y, pickedColor, pickedLayer, pickedObjectIndex}`
 */
export function getUniqueObjects({
  pickedColors,
  decodePickingColor
}: {
  pickedColors: Uint8Array;
  decodePickingColor: PickingColorDecoder;
}): PickedPixel[] {
  const uniqueColors = new Map();

  // Traverse all pixels in picking results and get unique colors
  if (pickedColors) {
    for (let i = 0; i < pickedColors.length; i += 4) {
      // Decode picked layer from color
      const pickedLayerIndex = pickedColors[i + 3] - 1;

      if (pickedLayerIndex >= 0) {
        const pickedColor = pickedColors.slice(i, i + 4);
        const colorKey = pickedColor.join(',');
        // eslint-disable-next-line
        if (!uniqueColors.has(colorKey)) {
          const pickedObject = decodePickingColor(pickedColor);
          // eslint-disable-next-line
          if (pickedObject) {
            uniqueColors.set(colorKey, {
              ...pickedObject,
              color: pickedColor
            });
          } else {
            log.error('Picked non-existent layer. Is picking buffer corrupt?')();
          }
        }
      }
    }
  }

  return Array.from(uniqueColors.values());
}