Mesh Renderer & Filter

using UnityEngine;

[RequireComponent(typeof(MeshFilter), typeof(MeshRenderer))]
public class ProceduralTriangle : MonoBehaviour
{
  void Start()
  {
      Mesh mesh = new Mesh();
      mesh.name = "Procedural Triangle";

      // 3 vertices of the triangle
      mesh.vertices = new Vector3[] {
          new Vector3(0f, 0f, 0f),
          new Vector3(1f, 0f, 0f),
          new Vector3(0.5f, 1f, 0f)
      };

      // Clockwise indices (viewed from the front)
      mesh.triangles = new int[] { 0, 1, 2 };

      // UV mapping: one texture coord per vertex
      mesh.uv = new Vector2[] {
          new Vector2(0f, 0f),
          new Vector2(1f, 0f),
          new Vector2(0.5f, 1f)
      };

      mesh.RecalculateNormals(); // Compute normals automatically

      GetComponent<MeshFilter>().mesh = mesh;
  }
}

using UnityEngine;

public class MeshRendererUtils : MonoBehaviour
{
  MeshRenderer rend;
  MaterialPropertyBlock mpb;

  void Awake()
  {
      rend = GetComponent<MeshRenderer>();
      mpb = new MaterialPropertyBlock();
  }

  // Read mesh bounds in world space
  void LogMeshInfo()
  {
      Mesh mesh = GetComponent<MeshFilter>().sharedMesh;
      Debug.Log($"Vertices: {mesh.vertexCount}");
      Debug.Log($"Triangles: {mesh.triangles.Length / 3}");
      Debug.Log($"Bounds: {rend.bounds.size}");
  }

  // Swap the Material on a specific sub-mesh (index 1 = window glass)
  public void SwapSubMesh(int index, Material mat)
  {
      Material[] mats = rend.materials; // Get a copy
      mats[index] = mat;
      rend.materials = mats;            // Assign back
  }

  // Per-instance color via PropertyBlock — keeps GPU Instancing
  public void SetInstanceColor(Color c)
  {
      rend.GetPropertyBlock(mpb);
      mpb.SetColor("_BaseColor", c);
      rend.SetPropertyBlock(mpb);
  }
}