104 lines
3.5 KiB
Dart
104 lines
3.5 KiB
Dart
import 'dart:typed_data';
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import 'package:wolf_dart/classes/matrix.dart';
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class VswapParser {
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/// Extracts the 64x64 wall textures from VSWAP.WL1
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static List<Matrix<int>> parseWalls(ByteData vswap) {
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// 1. Read Header
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int chunks = vswap.getUint16(0, Endian.little);
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int spriteStart = vswap.getUint16(2, Endian.little);
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// int soundStart = vswap.getUint16(4, Endian.little); // We don't need this yet
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// 2. Read Offsets (Where does each chunk start in the file?)
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List<int> offsets = [];
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for (int i = 0; i < spriteStart; i++) {
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offsets.add(vswap.getUint32(6 + (i * 4), Endian.little));
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}
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// 3. Extract the Wall Textures
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List<List<List<int>>> textures = [];
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// Walls are chunks 0 through (spriteStart - 1)
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for (int i = 0; i < spriteStart; i++) {
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int offset = offsets[i];
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if (offset == 0) continue; // Empty chunk
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// Walls are always exactly 64x64 pixels (4096 bytes)
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// Note: Wolf3D stores pixels in COLUMN-MAJOR order (Top to bottom, then left to right)
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List<List<int>> texture = List.generate(64, (_) => List.filled(64, 0));
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for (int x = 0; x < 64; x++) {
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for (int y = 0; y < 64; y++) {
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int byteIndex = offset + (x * 64) + y;
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texture[x][y] = vswap.getUint8(byteIndex);
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}
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}
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textures.add(texture);
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}
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return textures;
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}
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/// Extracts the compiled scaled sprites from VSWAP.WL1
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static List<Matrix<int>> parseSprites(ByteData vswap) {
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int chunks = vswap.getUint16(0, Endian.little);
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int spriteStart = vswap.getUint16(2, Endian.little); // 64
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int soundStart = vswap.getUint16(4, Endian.little);
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List<int> offsets = [];
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for (int i = 0; i < chunks; i++) {
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offsets.add(vswap.getUint32(6 + (i * 4), Endian.little));
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}
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List<Matrix<int>> sprites = [];
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// Sprites are located between the walls and the sounds
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for (int i = spriteStart; i < soundStart; i++) {
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int offset = offsets[i];
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if (offset == 0) continue; // Some chunks are empty placeholders
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// Initialize the 64x64 grid with 255 (The Magenta Transparency Color!)
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Matrix<int> sprite = List.generate(64, (_) => List.filled(64, 255));
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int leftPix = vswap.getUint16(offset, Endian.little);
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int rightPix = vswap.getUint16(offset + 2, Endian.little);
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// Read the offsets for each vertical column of the sprite
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List<int> colOffsets = [];
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for (int x = leftPix; x <= rightPix; x++) {
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colOffsets.add(
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vswap.getUint16(offset + 4 + ((x - leftPix) * 2), Endian.little),
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);
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}
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for (int x = leftPix; x <= rightPix; x++) {
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int colOffset = colOffsets[x - leftPix];
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if (colOffset == 0) continue;
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int cmdOffset = offset + colOffset;
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// Execute the column drawing commands
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while (true) {
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int endY = vswap.getUint16(cmdOffset, Endian.little);
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if (endY == 0) break; // 0 marks the end of the column
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endY ~/= 2; // Wolf3D stores Y coordinates multiplied by 2
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int pixelOfs = vswap.getUint16(cmdOffset + 2, Endian.little);
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int startY = vswap.getUint16(cmdOffset + 4, Endian.little);
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startY ~/= 2;
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for (int y = startY; y < endY; y++) {
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// The Carmack 286 Hack: pixelOfs + y gives the exact byte address!
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sprite[x][y] = vswap.getUint8(offset + pixelOfs + y);
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}
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cmdOffset += 6; // Move to the next 6-byte instruction
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}
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}
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sprites.add(sprite);
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}
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return sprites;
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}
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}
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