Renderer/src/main/java/electrosphere/client/foliagemanager/FoliageChunk.java

package electrosphere.client.foliagemanager;

import java.util.List;
import java.util.LinkedList;

import org.joml.Vector3d;
import org.joml.Vector3i;

import electrosphere.client.terrain.cache.ChunkData;
import electrosphere.engine.Globals;
import electrosphere.entity.EntityUtils;
import electrosphere.util.ds.octree.ChunkTree;
import electrosphere.util.ds.octree.ChunkTree.ChunkTreeNode;
import electrosphere.util.math.GeomUtils;

/**
 * A whole chunk of foliage
 */
public class FoliageChunk {
    
    /**
     * The world position of this chunk
     */
    Vector3i worldPos;
    Vector3d realPos;

    /**
     * The distance to draw at full resolution
     */
    static final double FULL_RES_DIST = 20;

    /**
     * The distance for half resolution
     */
    static final double HALF_RES_DIST = 40;

    /**
     * The octree holding all the chunks to evaluate
     */
    ChunkTree<FoliageCell> chunkTree;

    /**
     * Data for the current chunk
     */
    ChunkData currentChunkData;

    /**
     * Data for the above chunk
     */
    ChunkData aboveChunkData;

    /**
     * Constructor
     * @param worldPos The world position of the chunk
     */
    public FoliageChunk(Vector3i worldPos){
        this.worldPos = worldPos;
        this.realPos = Globals.clientWorldData.convertWorldToRealSpace(worldPos);
        this.chunkTree = new ChunkTree<FoliageCell>();
    }

    /**
     * Gets the world position of the chunk
     * @return The world position of the chunk
     */
    public Vector3i getWorldPos(){
        return worldPos;
    }

    /**
     * Initializes all cells in the chunk
     */
    public void initCells(){
        Globals.profiler.beginCpuSample("FoliageChunk.initCells");
        this.currentChunkData = Globals.clientTerrainManager.getChunkDataAtWorldPoint(worldPos);
        // //evaluate top cells if chunk above this one exists
        this.aboveChunkData = Globals.clientTerrainManager.getChunkDataAtWorldPoint(new Vector3i(worldPos).add(0,1,0));
        this.updateCells();
        Globals.profiler.endCpuSample();
    }

    /**
     * Updates all cells in the chunk
     */
    public void updateCells(){
        Globals.profiler.beginCpuSample("FoliageChunk.updateCells");
        Vector3d playerPos = EntityUtils.getPosition(Globals.playerEntity);
        //the sets to iterate through
        boolean updated = true;
        int attempts = 0;
        while(updated && attempts < 3){
            ChunkTreeNode<FoliageCell> rootNode = this.chunkTree.getRoot();
            updated = this.recursivelyUpdateCells(rootNode, playerPos);
            attempts++;
        }
        Globals.profiler.endCpuSample();
    }

    /**
     * Recursively update child nodes
     * @param node The root node
     * @param playerPos The player's position
     */
    private boolean recursivelyUpdateCells(ChunkTreeNode<FoliageCell> node, Vector3d playerPos){
        boolean updated = false;
        if(this.shouldSplit(playerPos, node)){
            //perform op
            ChunkTreeNode<FoliageCell> container = chunkTree.split(node);

            //do deletions
            this.recursivelyDestroy(node);

            //do creations
            container.getChildren().forEach(child -> {
                Vector3d realPos = new Vector3d(
                    worldPos.x * ChunkData.CHUNK_SIZE + child.getMinBound().x,
                    worldPos.y * ChunkData.CHUNK_SIZE + child.getMinBound().y,
                    worldPos.z * ChunkData.CHUNK_SIZE + child.getMinBound().z
                );
                child.convertToLeaf(new FoliageCell(worldPos, child.getMinBound(), realPos, 5 - child.getLevel()));
            });
            updated = true;
        } else if(this.shouldJoin(playerPos, node)) {
            //perform op
            ChunkTreeNode<FoliageCell> newLeaf = chunkTree.join(node);

            //do deletions
            this.recursivelyDestroy(node);

            //do creations
            newLeaf.convertToLeaf(new FoliageCell(worldPos, newLeaf.getMinBound(), realPos, 5 - newLeaf.getLevel()));
            updated = true;
        } else if(shouldGenerate(playerPos, node)){
            node.getData().generate();
            updated = true;
        } else if(!node.isLeaf()){
            List<ChunkTreeNode<FoliageCell>> children = new LinkedList<ChunkTreeNode<FoliageCell>>(node.getChildren());
            for(ChunkTreeNode<FoliageCell> child : children){
                boolean childUpdate = recursivelyUpdateCells(child, playerPos);
                updated = childUpdate || updated;
            }
        }
        return updated;
    }

    /**
     * Gets the minimum distance from a node to a point
     * @param pos the position to check against
     * @param node the node
     * @return the distance
     */
    public double getMinDistance(Vector3d pos, ChunkTreeNode<FoliageCell> node){
        Vector3i min = node.getMinBound();
        Vector3i max = node.getMaxBound();
        
        double minX = min.x + realPos.x;
        double minY = min.y + realPos.y;
        double minZ = min.z + realPos.z;

        double maxX = max.x + realPos.x;
        double maxY = max.y + realPos.y;
        double maxZ = max.z + realPos.z;
        return GeomUtils.getMinDistanceAABB(pos, new Vector3d(minX,minY,minZ), new Vector3d(maxX,maxY,maxZ));
    }

    /**
     * Gets whether this should be split or not
     * @param pos the player position
     * @param node The node
     * @return true if should split, false otherwise
     */
    public boolean shouldSplit(Vector3d pos, ChunkTreeNode<FoliageCell> node){
        //breaking out into dedicated function so can add case handling ie if we want
        //to combine fullres nodes into larger nodes to conserve on draw calls
        return
        node.isLeaf() &&
        node.canSplit() &&
        (
            (
                node.getLevel() < ChunkTree.MAX_LEVEL - 1 &&
                this.getMinDistance(pos, node) <= HALF_RES_DIST
            )
             ||
            (
                node.getLevel() < ChunkTree.MAX_LEVEL &&
                this.getMinDistance(pos, node) <= FULL_RES_DIST
            )
        )
        ;
    }

    /**
     * Gets whether this should be joined or not
     * @param pos the player position
     * @param node The node
     * @return true if should be joined, false otherwise
     */
    public boolean shouldJoin(Vector3d pos, ChunkTreeNode<FoliageCell> node){
        //breaking out into dedicated function so can add case handling ie if we want
        //to combine fullres nodes into larger nodes to conserve on draw calls
        return
        node.getLevel() > 0 &&
        !node.isLeaf() &&
        (
            (
                node.getLevel() == ChunkTree.MAX_LEVEL &&
                this.getMinDistance(pos, node) > FULL_RES_DIST
            )
             ||
            (
                this.getMinDistance(pos, node) > HALF_RES_DIST
            )
        )
        ;
    }

    /**
     * Checks if this cell should generate
     * @param pos the player's position
     * @param node the node
     * @return true if should generate, false otherwise
     */
    public boolean shouldGenerate(Vector3d pos, ChunkTreeNode<FoliageCell> node){
        return 
        node.isLeaf() &&
        node.getData() != null &&
        node.getData().containedEntities.size() < 1 &&
        (
            (
                node.getLevel() == ChunkTree.MAX_LEVEL
                // &&
                // this.getMinDistance(pos, node) <= FULL_RES_DIST
            )
             ||
            (
                node.getLevel() == ChunkTree.MAX_LEVEL - 1
                &&
                this.getMinDistance(pos, node) <= HALF_RES_DIST
            )
        )
        ;
    }

    /**
     * Checks if the node should have destroy called on it
     * @param node The node
     * @return true if should destroy, false otherwise
     */
    public boolean shouldDestroy(ChunkTreeNode<FoliageCell> node){
        return 
        node.getData() != null &&
        node.getData().containedEntities.size() > 0
        ;
    }

    /**
     * Destroys the foliage chunk
     */
    protected void destroy(){
        this.recursivelyDestroy(this.chunkTree.getRoot());
    }

    /**
     * Recursively destroy a tree
     * @param node The root of the tree
     */
    private void recursivelyDestroy(ChunkTreeNode<FoliageCell> node){
        if(node.getChildren().size() > 0){
            node.getChildren().forEach(child -> recursivelyDestroy(child));
        }
        if(node.getData() != null){
            node.getData().destroy();
        }
    }

    /**
     * Draws all cells in the chunk
     */
    protected void draw(){
        recursivelyDraw(this.chunkTree.getRoot());
    }

    /**
     * Recursively draws all nodes
     * @param node The root node
     */
    private void recursivelyDraw(ChunkTreeNode<FoliageCell> node){
        if(node.getChildren().size() > 0){
            node.getChildren().forEach(child -> recursivelyDraw(child));
        }
        if(node.getData() != null){
            node.getData().draw();
        }
    }
    

}