TypeScript function for converting a heightmap texture into Float32Array

computeHeights.ts

	function computeHeights(hmTexture: THREE.Texture, stats: any) {
		const image = hmTexture.image
		let w = image.naturalWidth
		let h = image.naturalHeight
		let canvas = document.createElement('canvas')
		canvas.width = w
		canvas.height = h
		let ctx = canvas.getContext('2d')
		ctx.drawImage(image, 0, 0, w, h)
		let data = ctx.getImageData(0, 0, w, h).data
		const heights = new Float32Array(w * h)
		let idx: number
		for (let y = 0; y < h; ++y) {
			for (let x = 0; x < w; ++x) {
				// idx pixel we want to get. Image has rgba, but we only need the r channel
				idx = (x + y * w) * 4

				// scale & store this altitude
				heights[x + y * w] = data[idx] / 255.0 * stats.dem_max
			}
		}
		// Free the resources and return
		data = ctx = canvas = null
		return heights
	}