MagicaVoxel file reader

VoxelFileReader.java

package com.robotality.game.graphics.voxel;

import com.badlogic.gdx.files.FileHandle;
import com.robotality.game.GameRuntimeException;

import java.io.BufferedInputStream;
import java.io.IOException;

class VoxelFileReader {

	@FunctionalInterface
	interface SizeReader {
		void size(int x, int y, int z);
	}

	@FunctionalInterface
	interface VoxelReader {
		void voxel(int x, int y, int z, byte colorIndex);
	}

	@FunctionalInterface
	interface PaletteReader {
		void palette(int colorIndex, int rgba);
	}

	private static class Chunk {
		long id;
		int contentSize;
		int childrenSize;
	}

	private byte[] buf = new byte[4];

	void read(FileHandle path,
			  SizeReader onSize,
			  VoxelReader onVoxel,
			  PaletteReader onPalette) throws IOException {

		BufferedInputStream input = path.read(1024);
		Chunk chunk = new Chunk();

		if (read32(input) != magicValue('V', 'O', 'X', ' ')) {
			throw new GameRuntimeException("Not a valid .vox file.");
		}

		if (read32(input) < 150) {
			throw new GameRuntimeException("Unsupported version.");
		}

		readChunk(input, chunk);
		if (chunk.id != magicValue('M', 'A', 'I', 'N')) {
			throw new GameRuntimeException("Main chunk expected.");
		}

		if (input.skip(chunk.contentSize) != chunk.contentSize) {
			throw new GameRuntimeException("Invalid number of bytes skipped.");
		}

		boolean foundPalette = false;

		for (; ; ) {

			try {
				readChunk(input, chunk);
			} catch (IOException ignored) {
				break;
			}

			if (chunk.id == magicValue('S', 'I', 'Z', 'E')) {

				int width = (int) read32(input);
				int depth = (int) read32(input);
				int height = (int) read32(input);

				onSize.size(width, depth, height);

			} else if (chunk.id == magicValue('X', 'Y', 'Z', 'I')) {

					int numVoxels = (int) read32(input);

					int x, y, z, c;

					for (int v = 0; v < numVoxels; v++) {
						x = input.read();
						y = input.read();
						z = input.read();
						c = input.read();

						onVoxel.voxel(x, y, z, (byte) (c & 0xff));
					}

			} else if (chunk.id == magicValue('R', 'G', 'B', 'A')) {

				// MagicaVoxel documentation:
				// - last color is not used
				// - the first color is corresponding to color index 1

				onPalette.palette(0, defaultPalette[0]);

				for (int p = 1; p < 256; p++) {
					int rgba = (int) read32(input);
					onPalette.palette(p, patchColor(rgba));
				}

				if (input.skip(4) != 4) {
					throw new GameRuntimeException("Unexpected EOF.");
				}

				foundPalette = true;

			} else {
				// unexpected chunk, ignore & skip
				int bytesToSkip = chunk.contentSize + chunk.childrenSize;
				if (input.skip(bytesToSkip) != bytesToSkip) {
					throw new GameRuntimeException("Invalid number of bytes skipped.");
				}
			}

		}

		if (!foundPalette) {
			// default palette
			for (int p = 0; p < 256; p++) {
				onPalette.palette(p, patchColor(defaultPalette[p]));
			}
		}

		input.close();
	}

	private void readChunk(BufferedInputStream input, Chunk chunk) throws IOException {
		chunk.id = read32(input);
		chunk.contentSize = (int) read32(input);
		chunk.childrenSize = (int) read32(input);
	}

	private long read32(BufferedInputStream input) throws IOException {
		if (input.read(buf) < 4) {
			throw new IOException();
		}
		return (buf[0] & 0xff) | ((buf[1] & 0xff) << 8) | ((buf[2] & 0xff) << 16) | ((buf[3] & 0xff) << 24);
	}

	private long magicValue(char c0, char c1, char c2, char c3) {
		return ((c3 << 24) & 0xff000000) | ((c2 << 16) & 0x00ff0000) | ((c1 << 8) & 0x0000ff00) | (c0 & 0x000000ff);
	}

	private int patchColor(int rgba) {
		int b = (rgba & 0x00ff0000) >> 16;
		int g = (rgba & 0x0000ff00) >> 8;
		int r = rgba & 0x000000ff;
		return (r << 24) | (g << 16) | (b << 8) | 0xff;
	}

	private static final int[] defaultPalette = {
			0x00000000, 0xffffffff, 0xffccffff, 0xff99ffff, 0xff66ffff, 0xff33ffff, 0xff00ffff, 0xffffccff, 0xffccccff, 0xff99ccff, 0xff66ccff, 0xff33ccff, 0xff00ccff, 0xffff99ff, 0xffcc99ff, 0xff9999ff,
			0xff6699ff, 0xff3399ff, 0xff0099ff, 0xffff66ff, 0xffcc66ff, 0xff9966ff, 0xff6666ff, 0xff3366ff, 0xff0066ff, 0xffff33ff, 0xffcc33ff, 0xff9933ff, 0xff6633ff, 0xff3333ff, 0xff0033ff, 0xffff00ff,
			0xffcc00ff, 0xff9900ff, 0xff6600ff, 0xff3300ff, 0xff0000ff, 0xffffffcc, 0xffccffcc, 0xff99ffcc, 0xff66ffcc, 0xff33ffcc, 0xff00ffcc, 0xffffcccc, 0xffcccccc, 0xff99cccc, 0xff66cccc, 0xff33cccc,
			0xff00cccc, 0xffff99cc, 0xffcc99cc, 0xff9999cc, 0xff6699cc, 0xff3399cc, 0xff0099cc, 0xffff66cc, 0xffcc66cc, 0xff9966cc, 0xff6666cc, 0xff3366cc, 0xff0066cc, 0xffff33cc, 0xffcc33cc, 0xff9933cc,
			0xff6633cc, 0xff3333cc, 0xff0033cc, 0xffff00cc, 0xffcc00cc, 0xff9900cc, 0xff6600cc, 0xff3300cc, 0xff0000cc, 0xffffff99, 0xffccff99, 0xff99ff99, 0xff66ff99, 0xff33ff99, 0xff00ff99, 0xffffcc99,
			0xffcccc99, 0xff99cc99, 0xff66cc99, 0xff33cc99, 0xff00cc99, 0xffff9999, 0xffcc9999, 0xff999999, 0xff669999, 0xff339999, 0xff009999, 0xffff6699, 0xffcc6699, 0xff996699, 0xff666699, 0xff336699,
			0xff006699, 0xffff3399, 0xffcc3399, 0xff993399, 0xff663399, 0xff333399, 0xff003399, 0xffff0099, 0xffcc0099, 0xff990099, 0xff660099, 0xff330099, 0xff000099, 0xffffff66, 0xffccff66, 0xff99ff66,
			0xff66ff66, 0xff33ff66, 0xff00ff66, 0xffffcc66, 0xffcccc66, 0xff99cc66, 0xff66cc66, 0xff33cc66, 0xff00cc66, 0xffff9966, 0xffcc9966, 0xff999966, 0xff669966, 0xff339966, 0xff009966, 0xffff6666,
			0xffcc6666, 0xff996666, 0xff666666, 0xff336666, 0xff006666, 0xffff3366, 0xffcc3366, 0xff993366, 0xff663366, 0xff333366, 0xff003366, 0xffff0066, 0xffcc0066, 0xff990066, 0xff660066, 0xff330066,
			0xff000066, 0xffffff33, 0xffccff33, 0xff99ff33, 0xff66ff33, 0xff33ff33, 0xff00ff33, 0xffffcc33, 0xffcccc33, 0xff99cc33, 0xff66cc33, 0xff33cc33, 0xff00cc33, 0xffff9933, 0xffcc9933, 0xff999933,
			0xff669933, 0xff339933, 0xff009933, 0xffff6633, 0xffcc6633, 0xff996633, 0xff666633, 0xff336633, 0xff006633, 0xffff3333, 0xffcc3333, 0xff993333, 0xff663333, 0xff333333, 0xff003333, 0xffff0033,
			0xffcc0033, 0xff990033, 0xff660033, 0xff330033, 0xff000033, 0xffffff00, 0xffccff00, 0xff99ff00, 0xff66ff00, 0xff33ff00, 0xff00ff00, 0xffffcc00, 0xffcccc00, 0xff99cc00, 0xff66cc00, 0xff33cc00,
			0xff00cc00, 0xffff9900, 0xffcc9900, 0xff999900, 0xff669900, 0xff339900, 0xff009900, 0xffff6600, 0xffcc6600, 0xff996600, 0xff666600, 0xff336600, 0xff006600, 0xffff3300, 0xffcc3300, 0xff993300,
			0xff663300, 0xff333300, 0xff003300, 0xffff0000, 0xffcc0000, 0xff990000, 0xff660000, 0xff330000, 0xff0000ee, 0xff0000dd, 0xff0000bb, 0xff0000aa, 0xff000088, 0xff000077, 0xff000055, 0xff000044,
			0xff000022, 0xff000011, 0xff00ee00, 0xff00dd00, 0xff00bb00, 0xff00aa00, 0xff008800, 0xff007700, 0xff005500, 0xff004400, 0xff002200, 0xff001100, 0xffee0000, 0xffdd0000, 0xffbb0000, 0xffaa0000,
			0xff880000, 0xff770000, 0xff550000, 0xff440000, 0xff220000, 0xff110000, 0xffeeeeee, 0xffdddddd, 0xffbbbbbb, 0xffaaaaaa, 0xff888888, 0xff777777, 0xff555555, 0xff444444, 0xff222222, 0xff111111
	};

}