Unity使用GL绘制图形

Paste_Image.png

左下角为原点

using UnityEngine;
using System.Collections.Generic;

public class Demo : GraphicsBehaviour
{

    // Use this for initialization
    void Start ()
    {

    }

    // Update is called once per frame
    void Update ()
    {

    }

    public override void OnRenderObject()
    {
        base.OnRenderObject();

        var points = new List<Vector2>();
        points.Add(new Vector2(0.1f, 0.2f));
        points.Add(new Vector2(0.5f, 0.25f));
        points.Add(new Vector2(0.8f, 0.95f));
        points.Add(new Vector2(0.7f, 0.88f));

        DrawPolygon(points, new Color(1, 0.92f, 0.016f, 0.5f), Color.red, PointMode.GLPoint);

        points = new List<Vector2>();
        points.Add(new Vector2(0.3f, 0.3f));
        points.Add(new Vector2(0.6f, 0.8f));
        points.Add(new Vector2(0.3f, 0.7f));
        points.Add(new Vector2(0.2f, 0.7f));

        DrawPolygon(points, new Color(1, 0.92f, 0.016f, 0.5f), Color.red, PointMode.GLPoint);
    }
}

using System.Collections.Generic;
using UnityEngine;

public class GraphicsBehaviour : MonoBehaviour
{
    public enum PointMode
    {
        GLPoint,
        ScreenPoint
    }

    private Material lineMaterial;

    void Awake()
    {
        // Unity has a built-in shader that is useful for drawing
        // simple colored things.
        var 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);
    }

    private Vector2 ScreenToGLPoint(Vector2 point)
    {
        point.x /= Screen.width;
        point.y /= Screen.height;

        return point;
    }

    public void DrawLine(Vector2 start, Vector2 end, Color color, PointMode pointMode = PointMode.ScreenPoint)
    {
        if (pointMode == PointMode.ScreenPoint)
        {
            start = ScreenToGLPoint(start);
            end = ScreenToGLPoint(end);
        }

        GL.PushMatrix();

        GL.LoadOrtho();

        GL.Begin(GL.LINES);

        GL.Color(color);

        GL.Vertex(start);
        GL.Vertex(end);

        GL.End();

        GL.PopMatrix();
    }

    public void DrawLines(List<Vector2> points, Color color, PointMode pointMode = PointMode.ScreenPoint)
    {
        if (points == null || points.Count == 0)
            return;

        if (pointMode == PointMode.ScreenPoint)
        {
            for (int i = 0; i < points.Count; i++)
                points[i] = ScreenToGLPoint(points[i]);
        }

        GL.PushMatrix();

        GL.LoadOrtho();

        GL.Begin(GL.LINES);

        GL.Color(color);

        for (int i = 0; i < points.Count; i++)
        {
            GL.Vertex(points[i]);
        }

        GL.End();

        GL.PopMatrix();
    }

    public void DrawPolygon(List<Vector2> points, Color fillColor, Color lineColor, PointMode pointMode = PointMode.ScreenPoint)
    {
        if (points == null || points.Count == 0)
            return;

        if (pointMode == PointMode.ScreenPoint)
        {
            for (int i = 0; i < points.Count; i++)
                points[i] = ScreenToGLPoint(points[i]);
        }

        GL.PushMatrix();

        GL.LoadOrtho();

        GL.Begin(GL.TRIANGLES);

        GL.Color(fillColor);

        for (int i = 0; i < points.Count; i++)
        {
            if (i < points.Count - 2)
            {
                GL.Vertex(points[0]);
                GL.Vertex(points[i + 1]);
                GL.Vertex(points[i + 2]);
            }
        }

        GL.End();

        GL.Begin(GL.LINES);

        GL.Color(lineColor);

        for (int i = 0; i < points.Count; i++)
        {
            GL.Vertex(points[i]);

            if(i != points.Count - 1)
                GL.Vertex(points[i + 1]);
        }

        GL.Vertex(points[0]);

        GL.End();

        GL.PopMatrix();
    }

    public virtual void OnRenderObject()
    {
        lineMaterial.SetPass(0);
    }
}