sandsim/js/world.js

// World management functions
let worldOffsetX = 0;
let worldOffsetY = 0;
let worldOffsetXBeforeDrag = 0;
let worldOffsetYBeforeDrag = 0;
let chunks = new Map(); // Map to store chunks with key "x,y"
let metadata = new Map(); // Map to store metadata for pixels
let generatedChunks = new Set(); // Set to track which chunks have been generated

function moveWorld(dx, dy) {
    worldOffsetX += dx;
    worldOffsetY += dy;
    updateCoordinatesDisplay();
    
    // Generate terrain for chunks around the current view
    generateChunksAroundPlayer();
}

function updateCoordinatesDisplay() {
    const chunkX = Math.floor(worldOffsetX / CHUNK_SIZE);
    const chunkY = Math.floor(worldOffsetY / CHUNK_SIZE);
    document.getElementById('coords').textContent = `Chunk: ${chunkX},${chunkY} | Offset: ${Math.floor(worldOffsetX)},${Math.floor(worldOffsetY)}`;
}

function getChunkKey(chunkX, chunkY) {
    return `${chunkX},${chunkY}`;
}

function getOrCreateChunk(chunkX, chunkY) {
    const key = getChunkKey(chunkX, chunkY);
    
    if (!chunks.has(key)) {
        // Create a new chunk with empty pixels
        const chunkData = new Array(CHUNK_SIZE * CHUNK_SIZE).fill(EMPTY);
        
        // Add floor at the bottom of the world (y = 0 and y = 1)
        if (chunkY === 0 || chunkY === 1) {
            // Fill the bottom row with walls
            for (let x = 0; x < CHUNK_SIZE; x++) {
                chunkData[(CHUNK_SIZE - 1) * CHUNK_SIZE + x] = WALL;
            }
        }
        
        // Special generation for the first chunk (0,0)
        if (chunkX === 0 && chunkY === 0) {
            generateFirstChunk(chunkData);
        }
        
        chunks.set(key, chunkData);
    }
    
    return chunks.get(key);
}

// Generate special terrain for the first chunk
function generateFirstChunk(chunkData) {
    // 1. Create a base layer of sand above the floor
    const floorY = CHUNK_SIZE - 1;
    const baseHeight = 10; // Base height of sand
    
    // Create two random hill points
    const hill1X = Math.floor(CHUNK_SIZE * 0.3);
    const hill2X = Math.floor(CHUNK_SIZE * 0.7);
    const hill1Height = baseHeight + Math.floor(Math.random() * 10) + 5; // 5-15 blocks higher
    const hill2Height = baseHeight + Math.floor(Math.random() * 10) + 5;
    
    // Generate height map for sand
    const heightMap = new Array(CHUNK_SIZE).fill(0);
    
    // Calculate heights based on distance from the two hills
    for (let x = 0; x < CHUNK_SIZE; x++) {
        // Distance from each hill (using a simple distance function)
        const dist1 = Math.abs(x - hill1X);
        const dist2 = Math.abs(x - hill2X);
        
        // Height contribution from each hill (inverse to distance)
        const h1 = hill1Height * Math.max(0, 1 - dist1 / (CHUNK_SIZE * 0.3));
        const h2 = hill2Height * Math.max(0, 1 - dist2 / (CHUNK_SIZE * 0.3));
        
        // Take the maximum height contribution
        heightMap[x] = Math.floor(baseHeight + Math.max(h1, h2));
    }
    
    // Find the lowest points for water
    let minHeight = Math.min(...heightMap);
    
    // Place sand according to the height map
    for (let x = 0; x < CHUNK_SIZE; x++) {
        const height = heightMap[x];
        for (let y = floorY - height; y < floorY; y++) {
            chunkData[y * CHUNK_SIZE + x] = SAND;
        }
        
        // 3. Add grass on top of the hills
        if (height > baseHeight + 3) { // Only on higher parts
            chunkData[(floorY - height) * CHUNK_SIZE + x] = GRASS;
        }
    }
    
    // 2. Add water in the lowest areas
    for (let x = 0; x < CHUNK_SIZE; x++) {
        const height = heightMap[x];
        // Add water where the height is close to the minimum
        if (height <= minHeight + 2) {
            // Add a few layers of water
            const waterDepth = 3;
            for (let d = 0; d < waterDepth; d++) {
                const y = floorY - height - d - 1;
                if (y >= 0) {
                    chunkData[y * CHUNK_SIZE + x] = WATER;
                }
            }
        }
    }
}

function getChunkCoordinates(worldX, worldY) {
    const chunkX = Math.floor(worldX / CHUNK_SIZE);
    const chunkY = Math.floor(worldY / CHUNK_SIZE);
    const localX = ((worldX % CHUNK_SIZE) + CHUNK_SIZE) % CHUNK_SIZE;
    const localY = ((worldY % CHUNK_SIZE) + CHUNK_SIZE) % CHUNK_SIZE;
    
    return { chunkX, chunkY, localX, localY };
}

function setPixel(worldX, worldY, type) {
    const { chunkX, chunkY, localX, localY } = getChunkCoordinates(worldX, worldY);
    const chunk = getOrCreateChunk(chunkX, chunkY);
    const index = localY * CHUNK_SIZE + localX;
    
    chunk[index] = type;
    
    // Assign random color index for natural elements
    if (type === DIRT || type === GRASS || type === STONE || type === WOOD || type === LEAF) {
        const colorIndex = Math.floor(Math.random() * 10);
        setMetadata(worldX, worldY, { ...getMetadata(worldX, worldY) || {}, colorIndex });
    }
    else if (type === WATER) {
        const colorIndex = Math.floor(Math.random() * 10);
        setMetadata(worldX, worldY, { ...getMetadata(worldX, worldY) || {}, colorIndex, waterColorTimer: 0 });
    }
}

function getPixel(worldX, worldY) {
    // Special case: floor at the bottom of the world (first two chunks)
    const floorChunkY = Math.floor(worldY / CHUNK_SIZE);
    if (worldY % CHUNK_SIZE === CHUNK_SIZE - 1 && (floorChunkY === 0 || floorChunkY === 1)) {
        return WALL;
    }
    
    const { chunkX, chunkY, localX, localY } = getChunkCoordinates(worldX, worldY);
    const key = getChunkKey(chunkX, chunkY);
    
    if (!chunks.has(key)) {
        return EMPTY;
    }
    
    const chunk = chunks.get(key);
    const index = localY * CHUNK_SIZE + localX;
    
    return chunk[index];
}

// Metadata functions to store additional information about pixels
function setMetadata(worldX, worldY, data) {
    const key = `${worldX},${worldY}`;
    metadata.set(key, data);
}

function getMetadata(worldX, worldY) {
    const key = `${worldX},${worldY}`;
    return metadata.get(key);
}

function removeMetadata(worldX, worldY) {
    const key = `${worldX},${worldY}`;
    metadata.delete(key);
}

// Move metadata when a pixel moves
function moveMetadata(fromX, fromY, toX, toY) {
    const data = getMetadata(fromX, fromY);
    if (data) {
        setMetadata(toX, toY, data);
        removeMetadata(fromX, fromY);
    }
}

function getVisibleChunks() {
    const visibleChunks = [];
    
    // Calculate visible chunk range
    const startChunkX = Math.floor(worldOffsetX / CHUNK_SIZE) - 1;
    const endChunkX = Math.ceil((worldOffsetX + canvas.width / PIXEL_SIZE) / CHUNK_SIZE) + 1;
    const startChunkY = Math.floor(worldOffsetY / CHUNK_SIZE) - 1;
    const endChunkY = Math.ceil((worldOffsetY + canvas.height / PIXEL_SIZE) / CHUNK_SIZE) + 1;
    
    for (let chunkY = startChunkY; chunkY < endChunkY; chunkY++) {
        for (let chunkX = startChunkX; chunkX < endChunkX; chunkX++) {
            visibleChunks.push({ chunkX, chunkY });
        }
    }
    
    return visibleChunks;
}