GLTest.cs

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

public class GLTest : MonoBehaviour {

static Material lineMaterial;
  
static void CreateLineMaterial ()
	{
		if (!lineMaterial){
			// Unity has a built-in shader that is useful for drawing
			// simple colored things.
			Shader shader = Shader.Find ("Hidden/Internal-Colored");
			lineMaterial = new Material (shader);
			lineMaterial.hideFlags = HideFlags.HideAndDontSave;
			// Turn on alpha blending
			lineMaterial.SetInt ("_SrcBlend", (int)UnityEngine.Rendering.BlendMode.SrcAlpha);
			lineMaterial.SetInt ("_DstBlend", (int)UnityEngine.Rendering.BlendMode.OneMinusSrcAlpha);
			// Turn backface culling off
			lineMaterial.SetInt ("_Cull", (int)UnityEngine.Rendering.CullMode.Off);
			// Turn off depth writes
			lineMaterial.SetInt ("_ZWrite", 0);
		}
	}
  
  public void OnRenderObject (){
    CreateLineMaterial ();
    /*定型フォーマットのようなもの*/
    lineMaterial.SetPass (0);
		GL.PushMatrix ();
    GL.MultMatrix (transform.localToWorldMatrix);
    /**/
    
    GL.Begin (GL.LINES);
    GL.Color (new Color (1.0f, 1.0f, 0, 0.8f));//以下は黄色
    //GL.Color (new Color (255, 255, 0, 0.8f));//0-255の書き方にすると、色鮮やかになる。正しい使用法かは不明
    
    /*始点、終点を指定していく*/
    GL.Vertex3(-4, 0, 25);
    GL.Vertex3(0, 4, 25);

    GL.Vertex3(0, 4, 25);
    GL.Vertex3(3, 7, 25);

    GL.Vertex3(3, 7, 25);
    GL.Vertex3(7, 10, 25);

    GL.Vertex3(7, 10, 25);
    GL.Vertex3(11, 12, 25);
    
    /*色を変えたい時は、GL.Colorを再度指定し直す*/
    GL.Color (new Color (0.0f, 1.0f, 0.25f, 0.8F));//以下は緑色
    
    //横軸
  　GL.Vertex3(-7, -2, 25);
    GL.Vertex3(14, -2, 25);

    //縦軸
    GL.Vertex3 (-7, -2, 25);
		GL.Vertex3 (-7, 15, 25);

		GL.End ();
    GL.PopMatrix ();
  }
}