Documentation

Unity Engine

User Manual

Script Reference

Unity Engine

Begin(int)

Begin drawing 3D primitives.
Read time 2 minutesLast updated 5 days ago

Definition

  • Type: Method
  • Namespace: UnityEngine
  • Assembly: UnityEngine.CoreModule
public static void Begin(int mode)

Parameters

mode

int
Primitives to draw: can be GL.TRIANGLES, GL.TRIANGLE_STRIP, GL.QUADS or GL.LINES.

Remarks

In OpenGL this matches 
glBegin
; on other graphics APIs the same functionality is emulated. Between GL.Begin and GL.End it is valid to call GL.Vertex, GL.Color, GL.TexCoord and other immediate mode drawing functions.
You should be careful about culling when drawing primitives yourself. The culling rules may be different depending on which graphics API the game is running. In most cases the safest way is to use 
Cull Off
command in the shader.
Additional Resources: GL.End.

Examples

using UnityEngine;public class Example : MonoBehaviour{    // Draws a Triangle, a Quad and a line    // with different colors    Material mat;    void OnPostRender()    {        if (!mat)        {            Debug.LogError("Please Assign a material on the inspector");            return;        }        GL.PushMatrix();        mat.SetPass(0);        GL.LoadOrtho();        GL.Begin(GL.TRIANGLES); // Triangle        GL.Color(new Color(1, 1, 1, 1));        GL.Vertex3(0.50f, 0.25f, 0);        GL.Vertex3(0.25f, 0.25f, 0);        GL.Vertex3(0.375f, 0.5f, 0);        GL.End();        GL.Begin(GL.QUADS); // Quad        GL.Color(new Color(0.5f, 0.5f, 0.5f, 1));        GL.Vertex3(0.5f, 0.5f, 0);        GL.Vertex3(0.5f, 0.75f, 0);        GL.Vertex3(0.75f, 0.75f, 0);        GL.Vertex3(0.75f, 0.5f, 0);        GL.End();        GL.Begin(GL.LINES); // Line        GL.Color(new Color(0, 0, 0, 1));        GL.Vertex3(0, 0, 0);        GL.Vertex3(0.75f, 0.75f, 0);        GL.End();        GL.PopMatrix();    }}