Beco

beco is a file format that is used for storing per-coordinate data.

Structure

beco files are little endian on Switch and big endian on Wii U.

Header

Offset	Type	Description
0x0	u32	Magic (0x00112233)
0x4	u32	Number of rows
0x8	u32	Divisor
0xc	u32	Padding

Offsets

Offset	Type	Description
0x0	u32[num_rows]	Offsets to row data, divided by 2 and relative to the start of the row section

Rows

Segment

Offset	Type	Description
0x0	u16	Custom data
0x2	u16	Length (X axis)

This structure is repeated until the entire row has been covered by segments. The sum of all segment lengths is equal to the length of the map on the X axis.

Operations

Getting data for a given coordinate

The algorithm that returns the custom data that is associated with a coordinate is very simple. It consists of determining the correct row index in the table, then iterating over segments in that row and returning the segment data when the X coordinate is within its bounds.

s32 Ecosystem::getMapArea(const EcoMapInfo& info, f32 posX, f32 posZ) const {
    posX = sead::Mathf::clamp(posX, -5000.0f, 4999.0f);
    posZ = sead::Mathf::clamp(posZ, -4000.0f, 4000.0f);

    const auto epsilon = [](float n) { return n >= 0.0f ? 0.5f : -0.5f; };

    s32 x = s32(posX + 5000.0f + epsilon(posX + 5000.0f));
    s32 z = s32(posZ + 4000.0f + epsilon(posZ + 4000.0f)) / info.mHeader->divisor;
    s32 row = sead::Mathi::clamp(z, 0, info.mHeader->num_rows - 2);

    if (info.mHeader->divisor == 10)
        x /= 10;

    if (info.mRowOffsets[row] >= info.mRowOffsets[row + 1])
        return -1;

    auto* segmentEnd = reinterpret_cast<const Segment*>(info.mRows + 2 * info.mRowOffsets[row + 1]);
    auto* segment = reinterpret_cast<const Segment*>(info.mRows + 2 * info.mRowOffsets[row]);
    s32 totalLength = 0;
    while (true) {
        totalLength += segment->length;
        if (x < totalLength)
            break;
        ++segment;
        if (segment >= segmentEnd)
            return -1;
    }
    return segment->value;
}

Source: https://github.com/zeldaret/botw/blob/022f029db1ef03d900fb54bad0807939c9695720/src/KingSystem/Ecosystem/ecoSystem.cpp#L100

Usage in Breath of the Wild

beco files are used in Breath of the Wild to map coordinates to arbitrary u16 data. Three beco files are used for different purposes: FieldMapArea.beco, MapTower.beco and LoadBalancer.beco.