128 lines
3 KiB
JavaScript
128 lines
3 KiB
JavaScript
"use strict"
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const MIN_ZOOM = .1
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const MAX_ZOOM = 6
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const ZOOM_STEP = .05
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export default function Camera () {
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let x = 0
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let y = 0
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let curZoom = 1
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const move = (byX, byY) => {
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x += byX / curZoom
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y += byY / curZoom
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}
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const calculateNewZoom = (inout) => {
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const factor = inout === 'in' ? 1 : -1
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const newzoom = curZoom + ZOOM_STEP * curZoom * factor
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const capped = Math.min(Math.max(newzoom, MIN_ZOOM), MAX_ZOOM)
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return capped
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}
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const canZoom = (inout) => {
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return curZoom != calculateNewZoom(inout)
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}
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const setZoom = (newzoom, viewportCoordCenter) => {
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if (curZoom == newzoom) {
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return false
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}
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const zoomFactor = 1 - (curZoom / newzoom)
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move(
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-viewportCoordCenter.x * zoomFactor,
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-viewportCoordCenter.y * zoomFactor,
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)
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curZoom = newzoom
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return true
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}
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/**
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* Zooms towards/away from the provided coordinate, if possible.
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* If at max or min zoom respectively, no zooming is performed.
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*/
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const zoom = (inout, viewportCoordCenter) => {
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return setZoom(calculateNewZoom(inout), viewportCoordCenter)
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}
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/**
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* Translate a coordinate in the viewport to a
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* coordinate in the world, rounded
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* @param {x, y} viewportCoord
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*/
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const viewportToWorld = (viewportCoord) => {
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const { x, y } = viewportToWorldRaw(viewportCoord)
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return { x: Math.round(x), y: Math.round(y) }
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}
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/**
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* Translate a coordinate in the viewport to a
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* coordinate in the world, not rounded
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* @param {x, y} viewportCoord
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*/
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const viewportToWorldRaw = (viewportCoord) => {
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return {
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x: (viewportCoord.x / curZoom) - x,
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y: (viewportCoord.y / curZoom) - y,
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}
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}
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/**
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* Translate a coordinate in the world to a
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* coordinate in the viewport, rounded
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* @param {x, y} worldCoord
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*/
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const worldToViewport = (worldCoord) => {
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const { x, y } = worldToViewportRaw(worldCoord)
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return { x: Math.round(x), y: Math.round(y) }
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}
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/**
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* Translate a coordinate in the world to a
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* coordinate in the viewport, not rounded
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* @param {x, y} worldCoord
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*/
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const worldToViewportRaw = (worldCoord) => {
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return {
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x: (worldCoord.x + x) * curZoom,
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y: (worldCoord.y + y) * curZoom,
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}
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}
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/**
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* Translate a 2d dimension (width/height) in the world to
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* one in the viewport, rounded
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* @param {w, h} worldDim
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*/
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const worldDimToViewport = (worldDim) => {
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const { w, h } = worldDimToViewportRaw(worldDim)
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return { w: Math.round(w), h: Math.round(h) }
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}
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/**
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* Translate a 2d dimension (width/height) in the world to
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* one in the viewport, not rounded
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* @param {w, h} worldDim
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*/
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const worldDimToViewportRaw = (worldDim) => {
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return {
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w: worldDim.w * curZoom,
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h: worldDim.h * curZoom,
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}
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}
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return {
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move,
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canZoom,
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zoom,
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worldToViewport,
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worldToViewportRaw,
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worldDimToViewport, // not used outside
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worldDimToViewportRaw,
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viewportToWorld,
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viewportToWorldRaw, // not used outside
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}
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}
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