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using System.Collections.Generic;
using UdonSharp;
using UnityEngine;
using VRC.SDK3.Rendering;
using VRC.Udon.Common.Interfaces;
public class DataDecoder : UdonSharpBehaviour
{
public RenderTexture sourceTexture;
public int tileToCheck = 0;
private int tileSize = 8;
// Minimum size (in pixels) of a tile. This is shared with our tixl operator.
private const int kMinTileSize = 4;
private const int kMaxTileSize = 128;
private Color32[] pixelData;
private bool hasData = false;
private int readWidth;
private int readHeight;
void Start() {}
void Update()
{
if (sourceTexture == null) return;
int requestWidth = Mathf.Min(tileSize, sourceTexture.width);
int requestHeight = sourceTexture.height;
int pixelCount = requestWidth * requestHeight;
if (pixelCount <= 0) return;
if (pixelData == null || pixelCount != pixelData.Length)
{
pixelData = new Color32[pixelCount];
hasData = false;
}
readWidth = requestWidth;
readHeight = requestHeight;
VRCAsyncGPUReadback.Request(sourceTexture,
0,
0, readWidth,
0, readHeight,
0, 1,
(IUdonEventReceiver)this);
if (hasData)
{
ProcessTiles();
hasData = false;
}
}
public override void OnAsyncGpuReadbackComplete(VRCAsyncGPUReadbackRequest request)
{
if (request.hasError) return;
if (pixelData != null && request.TryGetData(pixelData))
{
hasData = true;
}
}
private void ProcessTiles()
{
// Get the tile size.
{
int oldTileSize = tileSize;
tileSize = kMinTileSize;
tileSize = Parse24BitTile(0);
tileSize = Mathf.Clamp(tileSize, kMinTileSize, kMaxTileSize);
if (tileSize != oldTileSize) {
Debug.Log($"Tile size changed from {oldTileSize} to {tileSize}");
}
}
// Get the length. This is in units of subpixels. So we will need to access
// ceil(length/3) tiles.
int lengthSubpixels = Parse24BitTile(1);
int lengthTiles = (int) Mathf.Ceil(lengthSubpixels/3.0f);
// Collect all nibbles into a flat array. Note that these are still
// encoded.
var nibbles = new List<int>(lengthSubpixels);
for (int tile_i = 0; tile_i < lengthTiles; tile_i++) {
GetTileRGB(tile_i+2, out int r, out int g, out int b);
nibbles.Add(r);
if (nibbles.Count < nibbles.Capacity) {
nibbles.Add(g);
}
if (nibbles.Count < nibbles.Capacity) {
nibbles.Add(b);
}
}
// Convert nibbles to bytes.
var bytes = nibbles;
for (int i = 0; i < nibbles.Count/2; i++) {
// See DataEncoder.cs. It puts the upper 4 bits before the lower 4 bits.
bytes[i] = (nibbles[2*i] & 0xF0) | ((nibbles[2*i+1] & 0xF0) >> 4);
}
// Remove second half of list.
bytes.RemoveRange(nibbles.Count/2, nibbles.Count/2);
int tilesPerColumn = (int) Mathf.Floor(readHeight / tileSize);
}
private int Parse24BitTile(int tileIdx)
{
GetTileRGB(tileIdx, out int r, out int g, out int b);
int data = 0;
data |= DecodeNibble(r);
data |= DecodeNibble(g) << 4;
data |= DecodeNibble(b) << 8;
return data;
}
private int DecodeNibble(int subpixel) {
return (subpixel >> 4) & 0x0F;
}
private void GetTileRGB(int tileIdx, out int r, out int g, out int b)
{
r = 0;
g = 0;
b = 0;
int tileY = tileIdx * tileSize;
int centerY = tileY + tileSize / 2;
if (centerY >= readHeight) return;
int localX = readWidth / 2;
int localY = readHeight - 1 - centerY;
int index = localY * readWidth + localX;
if (index < 0 || index >= pixelData.Length) return;
Color32 c = pixelData[index];
r = c.r;
g = c.g;
b = c.b;
}
}
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