Monthly Archives: June 2016

Creating a grid mesh programmatically in Unity 3D

using System;
using System.Collections.Generic;
using UnityEngine;

public static class Grid
{

    public static void Create(bool withCollision)
    {
        GameObject gridObject = new GameObject();
        gridObject.name = "Grid";
        gridObject.transform.position = Vector3.zero;

        List<int> triangles = new List<int>();
        List<Vector3> vertices = new List<Vector3>();
        List<Vector2> uvs = new List<Vector2>();

        List<int> collision_triangles = new List<int>();
        List<Vector3> collision_vertices = new List<Vector3>();

        int vertexIndex = 0;
        int collisionVertexIndex = 0;

        int count = 64; // n+1 grid lines (n = even number)
        int n = count / 2; // halve count for +/- iteration

        float w = 0.05f; //line width
        float s = 1.0f; //width of space

        Vector3 v1;
        Vector3 v2;
        Vector3 v3;
        Vector3 v4;


        //Collision mesh

        if (withCollision)
        {
            v1 = new Vector3(-n, 0, -n);
            v2 = new Vector3(-n, 0, n);
            v3 = new Vector3(n, 0, n);
            v4 = new Vector3(n, 0, -n);

            collision_vertices.Add(v1);
            collision_vertices.Add(v2);
            collision_vertices.Add(v3);
            collision_vertices.Add(v4);

            collision_triangles.Add(collisionVertexIndex);
            collision_triangles.Add((collisionVertexIndex + 1));
            collision_triangles.Add((collisionVertexIndex + 2));
            collision_triangles.Add((collisionVertexIndex + 2));
            collision_triangles.Add((collisionVertexIndex + 3));
            collision_triangles.Add(collisionVertexIndex);

        }


        //Grid mesh
        for (int x = -n; x < n + 1; x++)
        {

            v1 = new Vector3((x * s), 0, -n);
            v2 = new Vector3((x * s), 0, n);
            v3 = new Vector3((x * s) + w, 0, n);
            v4 = new Vector3((x * s) + w, 0, -n);

            vertexIndex = vertices.Count;

            vertices.Add(v1);
            vertices.Add(v2);
            vertices.Add(v3);
            vertices.Add(v4);

            triangles.Add(vertexIndex);
            triangles.Add((vertexIndex + 1));
            triangles.Add((vertexIndex + 2));
            triangles.Add((vertexIndex + 2));
            triangles.Add((vertexIndex + 3));
            triangles.Add(vertexIndex);

            uvs.AddRange(Mats.Generic);

            //back face
            vertexIndex = vertices.Count;

            vertices.Add(v4);
            vertices.Add(v3);
            vertices.Add(v2);
            vertices.Add(v1);

            triangles.Add(vertexIndex);
            triangles.Add((vertexIndex + 1));
            triangles.Add((vertexIndex + 2));
            triangles.Add((vertexIndex + 2));
            triangles.Add((vertexIndex + 3));
            triangles.Add(vertexIndex);

            uvs.AddRange(Mats.Generic);

        }


        for (int z = -n; z < n + 1; z++)
        {

            v1 = new Vector3(-n, 0, (z * s));
            v2 = new Vector3(n, 0, (z * s));
            v3 = new Vector3(n, 0, (z * s) + w);
            v4 = new Vector3(-n, 0, (z * s) + w);

            vertexIndex = vertices.Count;

            vertices.Add(v1);
            vertices.Add(v2);
            vertices.Add(v3);
            vertices.Add(v4);

            triangles.Add(vertexIndex);
            triangles.Add((vertexIndex + 1));
            triangles.Add((vertexIndex + 2));
            triangles.Add((vertexIndex + 2));
            triangles.Add((vertexIndex + 3));
            triangles.Add(vertexIndex);

            uvs.AddRange(Mats.Generic);

            //back face
            vertexIndex = vertices.Count;

            vertices.Add(v4);
            vertices.Add(v3);
            vertices.Add(v2);
            vertices.Add(v1);

            triangles.Add(vertexIndex);
            triangles.Add((vertexIndex + 1));
            triangles.Add((vertexIndex + 2));
            triangles.Add((vertexIndex + 2));
            triangles.Add((vertexIndex + 3));
            triangles.Add(vertexIndex);

            uvs.AddRange(Mats.Generic);

        }

        Mesh mesh = new Mesh();
        mesh.vertices = vertices.ToArray();
        mesh.triangles = triangles.ToArray();
        mesh.uv = uvs.ToArray();

        mesh.RecalculateNormals();
        mesh.Optimize();

        MeshFilter meshFilter = gridObject.AddComponent<MeshFilter>();
        MeshRenderer meshRenderer = gridObject.AddComponent<MeshRenderer>();

        if (withCollision)
        {
            MeshCollider meshCollider = gridObject.AddComponent<MeshCollider>();
            Mesh collision_mesh = new Mesh();
            collision_mesh.vertices = collision_vertices.ToArray();
            collision_mesh.triangles = collision_triangles.ToArray();
            meshCollider.sharedMesh = collision_mesh;
        }

        meshRenderer.material = Mats.Grid();
        meshFilter.sharedMesh = mesh;

    }

}

Accessing strings in c++ from c#

Scenario; You may have some c++ code you wish to output string data to be used in a c# application.

#include <stdio.h>
#include <string.h>

extern "C"
{
	__declspec(dllexport) int GetString(char* buf,int n)
	{
		strncpy(buf,"my string in cpp", n);
		return 0;
	}
}
using System.Runtime.InteropServices;

[DllImport("mycppdll.dll", CallingConvention = CallingConvention.Cdecl)]
static extern int GetString(StringBuilder buffer, int capacity);

void csharp(){
StringBuilder sb = new StringBuilder(1000);
GetString(sb, sb.Capacity);
string mycppstring = sb.toString();
}