GL.MultiTexCoord3

Description

对实际纹理 unit 设置当前纹理坐标 (x,y,z)。

在 OpenGL 中，如果提供了多纹理处理，则其与给定纹理单位的 glMultiTexCoord 相匹配。在其他图形 API 中，对应的 功能是模拟实现的。

The Z component is used only when:
1. You access a cubemap (which you access with a vector coordinate, hence x,y & z).
2. You do "projective texturing", where the X & Y coordinates are divided by Z to get the final coordinate. This would be mostly useful for water reflections and similar things.

此函数只能在 GL.Begin 与 GL.End 函数之间加以调用。

using UnityEngine;

public class Example : MonoBehaviour
{
    // Changes between two textures assigned to a material
    // When pressed space
    Material mat;
    bool flagTex = true;

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            if (flagTex)
            {
                flagTex = false;
            }
            else
            {
                flagTex = true;
            }
        }
    }

    void OnPostRender()
    {
        if (!mat)
        {
            Debug.LogError("Please Assign a material on the inspector");
            return;
        }
        GL.PushMatrix();
        mat.SetPass(1);
        GL.LoadOrtho();
        GL.Begin(GL.QUADS);
        if (flagTex)
        {
            GL.MultiTexCoord3(0, 0, 0, 0); // main texture
        }
        else
        {
            GL.MultiTexCoord3(1, 0, 0, 0); // second texture
        }
        GL.Vertex3(0.25f, 0.25f, 0);
        if (flagTex)
        {
            GL.MultiTexCoord3(0, 0, 1, 0);
        }
        else
        {
            GL.MultiTexCoord3(1, 0, 1, 0);
        }
        GL.Vertex3(0.25f, 0.75f, 0);
        if (flagTex)
        {
            GL.MultiTexCoord3(0, 1, 1, 0);
        }
        else
        {
            GL.MultiTexCoord3(1, 1, 1, 0);
        }
        GL.Vertex3(0.75f, 0.75f, 0);
        if (flagTex)
        {
            GL.MultiTexCoord3(0, 1, 0, 0);
        }
        else
        {
            GL.MultiTexCoord3(1, 1, 0, 0);
        }
        GL.Vertex3(0.75f, 0.25f, 0);
        GL.End();
        GL.PopMatrix();
    }
}