BSP Structures

public interface DStruct extends Struct {
    int getSize();
}

public class DPlane implements DStruct {
    public Vector3f normal;  // Plane normal vector
    public float dist;       // Distance from origin
    public int type;         // Plane axis type
}

public class DVertex implements DStruct {
    public Vector3f point;  // 3D position
}

public class DEdge implements DStruct {
    public int[] v = new int[2];  // Vertex indices
}

public class DFace implements DStruct {
    public static final int MAXLIGHTMAPS = 4;
    
    public int pnum;                // Plane number
    public byte side;               // Side of plane (0 or 1)
    public byte onnode;             // 1 if on node, 0 if in leaf
    public int fstedge;             // First surfedge index
    public int numedge;             // Number of surfedges
    public int texinfo;             // Texture info index
    public int dispInfo;            // Displacement info index (-1 if not a displacement)
    public int surfaceFogVolumeID;  // Fog volume ID
    public byte[] styles;           // Lightmap styles [MAXLIGHTMAPS]
    public int lightofs;            // Offset into lightmap data
    public float area;              // Face area in square units
    public int[] lightmapTextureMinsInLuxels;  // [2] Lightmap mins
    public int[] lightmapTextureSizeInLuxels;  // [2] Lightmap size
    public int origFace;            // Original face index
    public int numPrims;            // Number of primitives
    public int firstPrimID;         // First primitive ID
    public int smoothingGroups;     // Smoothing groups
}

public class DBrush implements DStruct {
    public int fstside;              // First brush side index
    public int numside;              // Number of sides
    public Set<BrushFlag> contents;  // Contents flags
}

public enum BrushFlag {
    CONTENTS_SOLID,           // Blocks player and NPC movement
    CONTENTS_WINDOW,          // Transparent but blocks bullets
    CONTENTS_GRATE,           // Grate (bullets pass through)
    CONTENTS_SLIME,           // Slime volume
    CONTENTS_WATER,           // Water volume
    CONTENTS_BLOCKLOS,        // Blocks line of sight
    CONTENTS_OPAQUE,          // Blocks visibility
    CONTENTS_AREAPORTAL,      // Area portal brush
    CONTENTS_PLAYERCLIP,      // Blocks only players
    CONTENTS_MONSTERCLIP,     // Blocks only NPCs
    CONTENTS_DETAIL,          // Detail brush (doesn't split BSP)
    CONTENTS_TRANSLUCENT,     // Translucent brush
    CONTENTS_LADDER,          // Ladder volume
    CONTENTS_HITBOX,          // Hitbox brush
    // ... and more
}

public class DModel implements DStruct {
    public Vector3f mins;     // Bounding box minimum
    public Vector3f maxs;     // Bounding box maximum
    public Vector3f origin;   // Model origin
    public int headnode;      // BSP tree head node index
    public int fstface;       // First face index
    public int numface;       // Number of faces
}

public class DTexInfo implements DStruct {
    public static final int TEXINFO_NODE = -1;
    
    public float[][] textureVecsTexels;   // [2][4] Texture UV mapping
    public float[][] lightmapVecsLuxels;  // [2][4] Lightmap UV mapping
    public Set<SurfaceFlag> flags;        // Surface flags
    public int texdata;                   // Texture data index
}

public enum SurfaceFlag {
    SURF_LIGHT,      // Emits light (light value in texture)
    SURF_SKY2D,      // 2D skybox
    SURF_SKY,        // 3D skybox
    SURF_WARP,       // Turbulent water warp
    SURF_TRANS,      // Translucent surface
    SURF_NOPORTAL,   // Cannot place portals on this surface
    SURF_TRIGGER,    // Trigger surface
    SURF_NODRAW,     // Don't draw this surface
    SURF_HINT,       // BSP hint surface
    SURF_SKIP,       // Skip surface (non-closed brushes)
    SURF_NOLIGHT,    // Don't calculate lighting
    SURF_BUMPLIGHT,  // Calculate bumpmapped lighting
    SURF_NOSHADOWS,  // Don't receive shadows
    SURF_NODECALS,   // Don't receive decals
    SURF_NOCHOP,     // Don't subdivide patches
    SURF_HITBOX      // Part of a hitbox
}

public class DDispInfo implements DStruct {
    public static final int DISP_INFO_FLAG_HAS_MULTIBLEND = 0x40000000;
    public static final int DISP_INFO_FLAG_MAGIC = 0x80000000;
    
    public Vector3f startPos;       // Starting position
    public int dispVertStart;       // Index into disp verts
    public int dispTriStart;        // Index into disp tris
    public int power;               // Displacement power (2-4)
    public int minTess;             // Minimum tesselation
    public float smoothingAngle;    // Smoothing angle
    public int contents;            // Surface contents
    public int mapFace;             // Face index
    public int lightmapAlphaStart;  // Lightmap alpha start
    public int lightmapSamplePositionStart;
    public int[] allowedVerts;      // [10] Allowed vertices
}

public class DOverlay implements DStruct {
    public static final int OVERLAY_BSP_FACE_COUNT = 64;
    
    public int id;                  // Overlay ID
    public int texinfo;             // Texture info index
    public int faceCountAndRenderOrder;
    public int[] ofaces;            // [64] Face indices
    public float[] u;               // [2] U texture coords
    public float[] v;               // [2] V texture coords
    public Vector3f[] uvpoints;     // [4] UV points
    public Vector3f origin;         // Overlay origin
    public Vector3f basisNormal;    // Basis normal
}

BspData bspData = bspFile.getBspData();

for (DFace face : bspData.faces) {
    // Get the plane
    DPlane plane = bspData.planes.get(face.pnum);
    
    // Get texture info
    DTexInfo texInfo = bspData.texinfos.get(face.texinfo);
    DTexData texData = bspData.texdatas.get(texInfo.texdata);
    String textureName = bspData.texnames.get(texData.nameStringTableID);
    
    // Check if it's a displacement
    if (face.dispInfo >= 0) {
        DDispInfo disp = bspData.dispinfos.get(face.dispInfo);
        int vertCount = disp.getVertexCount();
        System.out.println("Displacement with " + vertCount + " vertices");
    }
    
    // Check surface flags
    if (texInfo.flags.contains(SurfaceFlag.SURF_NODRAW)) {
        continue; // Skip nodraw surfaces
    }
}

for (DModel model : bspData.models) {
    System.out.println("Model bounds: " + model.mins + " to " + model.maxs);
    
    // Iterate through model's faces
    for (int i = 0; i < model.numface; i++) {
        DFace face = bspData.faces.get(model.fstface + i);
        // Process face...
    }
}

for (DBrush brush : bspData.brushes) {
    if (brush.isPlayerClip()) {
        System.out.println("Found player clip brush");
    }
    
    // Iterate through brush sides
    for (int i = 0; i < brush.numside; i++) {
        DBrushSide side = bspData.brushSides.get(brush.fstside + i);
        // Process brush side...
    }
}