Space and Matrix Transformations - Building a 3D Engine

using System;
using System.Collections.Generic;
using System.Text;
using AGE_Engine3D.Math;
using AGE_Engine3D.Text;
using AGE_Engine3D.RenderObjects;
using Tao.OpenGl;

namespace AGE_Engine3D.HUD
{
    public class AGE_ScreenText : IRenderOpenGL 
    {

        #region Fields
        bool _Isvisible = true;
        AGE_Matrix_44 _WorldMatrix = AGE_Matrix_44.Identity();
        AGE_Matrix_44 ViewMatrix;
        float CurrentScreenWidth;
        float CurrentScreenHieght;
        float FontSize = 20;
        AGE_Color4f DefaultColor = new AGE_Color4f(1,0,0,1);
        FontAlign DefaultAlin = FontAlign.LEFT;
        List<AGE_ScreenTextItem> TextQueue = new List<AGE_ScreenTextItem>();
        public bool IsVisable { get { return _Isvisible; } }
        IFont FontContainer = null;
        #endregion

        #region IRenderOpenGL Members

        public void RenderOpenGL()
        {
            if (this._Isvisible && this.TextQueue.Count > 0)
            {
                this.CreatMatrixTransform();

                #region Set the Model View Matrix
                Gl.glMatrixMode(Gl.GL_PROJECTION);
                Gl.glPushMatrix();
                Gl.glLoadMatrixf(this.ViewMatrix.GetListValues());
                Gl.glMatrixMode(Gl.GL_MODELVIEW);
                Gl.glLoadIdentity();
                #endregion

                this.FontContainer = ResourceManager.GetFont("Verdana");
                AGE_Matrix_44 Location;
                foreach (AGE_ScreenTextItem TextItem in this.TextQueue)
                {
                    float FontHieght = this.FontContainer.CharHeight * TextItem.Size;
                    AGE_Vector3Df Loc = TextItem.Location;
                    Loc.Y += FontHieght;
                    Loc.Z = 1f;
                    AGE_Vector3Df Scale = new AGE_Vector3Df(FontHieght, -FontHieght, 1);

                    this.FontContainer.Alignment = TextItem.Align;
                    Gl.glColor4fv(TextItem.Color.ToArray4f());
                    foreach (string Tmptext in TextItem.TextList)
                    {
                        Location = AGE_Matrix_44.HWorld(ref Loc, ref Scale);
                        Gl.glLoadMatrixf(Location.GetListValues());

                        this.FontContainer.glPrint(Tmptext);

                        Loc.Y += FontHieght;
                    }

                }
                Gl.glMatrixMode(Gl.GL_PROJECTION);
                Gl.glPopMatrix();
                this.TextQueue.Clear();
            }
        }

        public void AddText(List<string> NewText, AGE_Vector3Df Location)
        {
            if (NewText.Count > 0)
            {
                AGE_ScreenTextItem tmp = new AGE_ScreenTextItem();
                tmp.TextList.AddRange(NewText);
                tmp.Location = Location;
                tmp.Color = this.DefaultColor;
                tmp.Align = this.DefaultAlin;
                tmp.Size = this.FontSize;
                this.TextQueue.Add(tmp);
            }
        }

        #endregion

        #region Methods

        public void CreatMatrixTransform()
        {
            if (this.CurrentScreenHieght != SceneGraph.ScreenHeight ||
                this.CurrentScreenWidth != SceneGraph.ScreenWidth)
            {
                this.CurrentScreenHieght = SceneGraph.ScreenHeight;
                this.CurrentScreenWidth = SceneGraph.ScreenWidth;
                AGE_Vector3Df Eye = new AGE_Vector3Df(0, 0, 1);
                AGE_Vector3Df Target = new AGE_Vector3Df(0, 0, -1);
                AGE_Vector3Df Up = new AGE_Vector3Df(0, 1, 0);
                AGE_Matrix_44 temp = AGE_Matrix_44.HView(ref Eye, ref Target, ref Up);
                this.ViewMatrix = AGE_Matrix_44.HOrtho(0, this.CurrentScreenWidth, 0, this.CurrentScreenHieght, 0, 1) * temp;
            }
        } 

        #endregion
    }

    class AGE_ScreenTextItem
    {
        public List<string> TextList = new List<string>();
        public AGE_Vector3Df Location;
        public FontAlign Align = FontAlign.LEFT;
        public AGE_Color4f Color;
        public float Size;

    }
}