94 lines
3.4 KiB
C#
94 lines
3.4 KiB
C#
using System.Collections.Generic;
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using UnityEngine;
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using UnityEngine.Assertions;
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public class GrassField : MonoBehaviour {
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public int size = 100;
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public int numChunks = 5;
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public GrassChunk chunkPrefab;
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private struct BladeData {
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public Vector3 rootPosition;
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public Vector3 tipPosition;
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}
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public void GenerateGrassField() {
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Debug.Log("Generating grass field... ");
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var blades = GenerateBlades();
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CreateChunks(blades);
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Debug.Log("Generating grass field done");
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}
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private BladeData[] GenerateBlades() {
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var blades = new BladeData[size * size];
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for (int x = 0; x < size; x++)
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for (int y = 0; y < size; y++) {
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var i = x + y * size;
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blades[i].rootPosition = new Vector3(x + 0.5f, 0.0f, y + 0.5f);
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blades[i].tipPosition = blades[i].rootPosition + new Vector3(0.0f, 1.0f, 0.0f);
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}
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return blades;
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}
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private void CreateChunks(BladeData[] blades) {
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GameObject chunks;
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// If a child called "Chunks" exists, destroy it -> children are also destroyed
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var chunksTransform = gameObject.transform.Find("Chunks");
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if (chunksTransform != null) {
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// Destroy(obj) does not work in edit mode
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DestroyImmediate(chunksTransform.gameObject);
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}
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// create GameObject "Chunks" as a container for all GrassChunk objects
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chunks = new GameObject("Chunks");
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chunks.transform.SetParent(this.transform, false);
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var chunkSize = ((float)size) / numChunks;
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for (int x = 0; x < numChunks; x++)
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for (int y = 0; y < numChunks; y++) {
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var chunkPos = new Vector3(x, 0.0f, y) * chunkSize;
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// bounds in local space of grass field
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var bounds = new Bounds(
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new Vector3(0.5f * chunkSize, 0.5f, 0.5f * chunkSize),
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new Vector3(chunkSize, 1.01f, chunkSize)
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);
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List<Vector3> rootPositions = new();
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List<Vector3> tipPositions = new();
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List<int> indices = new();
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foreach (var blade in blades) {
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var localRootPos = blade.rootPosition - chunkPos;
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if (bounds.Contains(localRootPos)) {
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rootPositions.Add(localRootPos);
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var localTipPos = blade.tipPosition - chunkPos;
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tipPositions.Add(localTipPos);
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indices.Add(rootPositions.Count - 1);
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}
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}
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var mesh = new Mesh();
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// 16 bit (default) supports 65536 vertices, 32 bit supports 4 billion
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// mesh.indexFormat = UnityEngine.Rendering.IndexFormat.UInt32;
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mesh.name = "grass_chunk[" + x + "," + y + "]";
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mesh.SetVertices(rootPositions);
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// do not calculate bounding box - will be set manually
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mesh.SetIndices(indices, MeshTopology.Points, 0, false);
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// Vector3 UVs are possible
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mesh.SetUVs(0, tipPositions);
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var chunk = Instantiate(chunkPrefab, chunks.transform);
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chunk.name = "Chunk [" + x + ", " + y +"]";
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chunk.transform.localPosition = chunkPos;
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var meshFilter = chunk.GetComponent<MeshFilter>();
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meshFilter.sharedMesh = mesh;
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var meshRenderer = chunk.GetComponent<MeshRenderer>();
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meshRenderer.localBounds = bounds;
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}
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}
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}
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