From e6ec165987a5a5735462f71709b06e80bd2a96b1 Mon Sep 17 00:00:00 2001
From: redbirdly <155550833+redbirdly@users.noreply.github.com>
Date: Tue, 5 Nov 2024 15:14:48 +0800
Subject: [PATCH] Upload occlusion mod

---
 mods/occlusion.js | 149 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 149 insertions(+)
 create mode 100644 mods/occlusion.js

diff --git a/mods/occlusion.js b/mods/occlusion.js
new file mode 100644
index 00000000..d493710b
--- /dev/null
+++ b/mods/occlusion.js
@@ -0,0 +1,149 @@
+const DEFAULT_LIGHT_FACTOR = 0.8;
+const MIN_LIGHT_INTENSITY = 0.6;  // If pixel is completely obscured, it will still have this amount of light
+
+const MAX_DIRECT_NEIGHBORS = 4;  // getNeighbors() returns max 4 pixels
+const FOLLOWUP_COORDS_TO_CHECK = [
+	[-1, -1], [-1, 1], [1, -1], [1, 1],
+	[-2, 0], [2, 0], [0, -2], [0, 2],
+	[-3, 0], [3, 0], [0, -3], [0, 3],
+	[-4, 0], [4, 0], [0, -4], [0, 4]
+];
+
+// Pre-initialize the list of transparent elements
+let transparentElementsTmp = "glass,stained_glass,glass_shard,solid_diamond,ice,led_r,led_g,led_b".split(",");
+let transparentElements = [];
+
+// Function to create the list of transparent elements based on their properties
+function initializeTransparentElements() {
+	Object.keys(elements).forEach(elementName => {
+		const element = elements[elementName];
+
+		// Check if the element is in a gas or liquid state
+		if (element.state === "gas") {
+			transparentElements.push(elementName);
+		}
+
+		// Check if the element's category is "special"
+		if (element.category === "special") {
+			transparentElements.push(elementName);
+		}
+
+		// Check if the element has a custom flag for transparency
+		if (element.putInTransparentList) {
+			transparentElements.push(elementName);
+		}
+	});
+}
+
+// Call the function once at startup to populate the transparentElements list
+initializeTransparentElements();
+
+// Customizable frame interval for recalculating brightness
+const calculateEveryNFrames = 2;
+let frameCounter = 0;
+
+// Cache for storing pixel brightnesses
+let pixelBrightnessCache = {};
+
+// scaleList should only be defined once
+if (typeof scaleList === 'undefined') {
+	function scaleList(numbers, scale) {
+		return numbers.map(number => number * scale);
+	}
+}
+
+function isOutOfBounds(x, y) {
+	return x >= width || y >= height || x < 0 || y < 0;
+}
+
+function getOutOfBoundsNeighbors(pixel) {
+	const outOfBoundsNeighbors = [];
+
+	// Define the 4 direct neighbors: left, right, top, bottom
+	const neighborsToCheck = [
+		{ x: pixel.x - 1, y: pixel.y },
+		{ x: pixel.x + 1, y: pixel.y },
+		{ x: pixel.x, y: pixel.y - 1 },
+		{ x: pixel.x, y: pixel.y + 1 }
+	];
+
+	// Check each of the neighbors to see if they are out of bounds
+	neighborsToCheck.forEach(neighbor => {
+		if (isOutOfBounds(neighbor.x, neighbor.y)) {
+			outOfBoundsNeighbors.push(neighbor);
+		}
+	});
+
+	return outOfBoundsNeighbors;
+}
+
+// Iterate over each pixel and either calculate or draw occlusion lighting
+function applyLightingToPixels(ctx) {
+	// Recalculate pixel brightnesses every `n` frames
+	if (frameCounter % calculateEveryNFrames === 0) {
+		currentPixels.forEach(pixel => {
+			const brightness = calculateBrightness(pixel);
+			pixelBrightnessCache[`${pixel.x},${pixel.y}`] = brightness;  // Cache the brightness
+		});
+	}
+
+	// Draw pixels based on cached brightness
+	currentPixels.forEach(pixel => {
+		const brightness = pixelBrightnessCache[`${pixel.x},${pixel.y}`] || 1;  // Default to full brightness if not calculated yet
+		drawPixelShade(ctx, pixel, brightness);
+	});
+
+	// Increment the frame counter
+	frameCounter++;
+}
+
+// Darken a pixel based on brightness
+function drawPixelShade(ctx, pixel, brightness) {
+	ctx.globalAlpha = 1.0;
+	ctx.fillStyle = `rgba(0, 0, 0, ${1 - brightness})`;
+	ctx.fillRect(pixel.x * pixelSize, pixel.y * pixelSize, pixelSize, pixelSize);
+}
+
+// Compute brightness for a given pixel
+function calculateBrightness(pixel) {
+	const neighboringPixelsCount = getNeighbors(pixel).length + getOutOfBoundsNeighbors(pixel).length;
+
+	// If the pixel has enough light-blocking neighbors, perform a deeper search
+	if (neighboringPixelsCount >= MAX_DIRECT_NEIGHBORS) {
+		const lightFactor = computeBrightnessFurther(pixel);
+		return adjustBrightness(lightFactor);
+	}
+
+	return 1;  // Full brightness
+}
+
+// Compute brightness based on further pixels that block light
+function computeBrightnessFurther(pixel) {
+	let lightBlockers = 0;
+
+	FOLLOWUP_COORDS_TO_CHECK.forEach(offset => {
+		const [dx, dy] = offset;
+		const xCoord = pixel.x + dx;
+		const yCoord = pixel.y + dy;
+
+		if (isOutOfBounds(xCoord, yCoord)) {
+			lightBlockers++;
+			return;
+		}
+
+		// Check if the element is transparent
+		const element = pixelMap[xCoord][yCoord];
+		if (element != undefined && !transparentElements.includes(element.element)) {
+			lightBlockers++;
+		}
+	});
+
+	return 1 - (lightBlockers / FOLLOWUP_COORDS_TO_CHECK.length);
+}
+
+// Adjust brightness based on light factor
+function adjustBrightness(lightFactor) {
+	return lightFactor * DEFAULT_LIGHT_FACTOR + MIN_LIGHT_INTENSITY;
+}
+
+renderPostPixel(applyLightingToPixels);