文章目录

• 1.问题描述
• 2.问题解答
• 3.EBO表示法
• 参考文章：

1.问题描述

在openGL中下面这个数组的如何理解：

const float vertices[] = {                  //立方体数组
	-0.5f, -0.5f, -0.5f, 1.0f,0.0f,0.0f,
	0.5f, -0.5f, -0.5f,  1.0f,0.0f,0.0f,
	0.5f,  0.5f, -0.5f,  1.0f,0.0f,0.0f,
	0.5f,  0.5f, -0.5f,  1.0f,0.0f,0.0f,
	-0.5f,  0.5f, -0.5f,  1.0f,0.0f,0.0f,
	-0.5f, -0.5f, -0.5f,  1.0f,0.0f,0.0f,

	-0.5f, -0.5f,  0.5f,  0.0f,1.0f,0.0f,
	0.5f, -0.5f,  0.5f,  0.0f,1.0f,0.0f,
	0.5f,  0.5f,  0.5f,  0.0f,1.0f,0.0f,
	0.5f,  0.5f,  0.5f,  0.0f,1.0f,0.0f,
	-0.5f,  0.5f,  0.5f,  0.0f,1.0f,0.0f,
	-0.5f, -0.5f,  0.5f,  0.0f,1.0f,0.0f,

	-0.5f,  0.5f,  0.5f,  0.0f,0.0f,1.0f,
	-0.5f,  0.5f, -0.5f,  0.0f,0.0f,1.0f,
	-0.5f, -0.5f, -0.5f,  0.0f,0.0f,1.0f,
	-0.5f, -0.5f, -0.5f,  0.0f,0.0f,1.0f,
	-0.5f, -0.5f,  0.5f,  0.0f,0.0f,1.0f,
	-0.5f,  0.5f,  0.5f,  0.0f,0.0f,1.0f,

	0.5f,  0.5f,  0.5f,  0.5f,0.0f,0.0f,
	0.5f,  0.5f, -0.5f,  0.5f,0.0f,0.0f,
	0.5f, -0.5f, -0.5f,  0.5f,0.0f,0.0f,
	0.5f, -0.5f, -0.5f,  0.5f,0.0f,0.0f,
	0.5f, -0.5f,  0.5f,  0.5f,0.0f,0.0f,
	0.5f,  0.5f,  0.5f,  0.5f,0.0f,0.0f,

	-0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,
	0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,
	0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,
	0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,
	-0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,
	-0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,

	-0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f,
	0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f,
	0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,
	0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,
	-0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,
	-0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f
};

2.问题解答

每3行就是一个三角形；
每一行的前三个值是三角形的每个点在空间中的位置，后三个值是颜色或者法向量。
立方体有6个面，每个面需要2个三角形拼接成立方体的一个面，共有12个三角形，
所以代码分开后有12个3行点。

const float vertices[] = {                  //立方体数组
/*------------------三角形EGC----------------------*/
 -0.5f, -0.5f, -0.5f, 1.0f,0.0f,0.0f,//E
 0.5f, -0.5f, -0.5f,  1.0f,0.0f,0.0f,//G
 0.5f,  0.5f, -0.5f,  1.0f,0.0f,0.0f,//C
  
 /*------------------三角形CAE----------------------*/
 0.5f,  0.5f, -0.5f,  1.0f,0.0f,0.0f,//C
 -0.5f,  0.5f, -0.5f,  1.0f,0.0f,0.0f,//A
 -0.5f, -0.5f, -0.5f,  1.0f,0.0f,0.0f,//E
  
  /*------------------三角形FHD----------------------*/
 -0.5f, -0.5f,  0.5f,  0.0f,1.0f,0.0f,//F
 0.5f, -0.5f,  0.5f,  0.0f,1.0f,0.0f,//H
 0.5f,  0.5f,  0.5f,  0.0f,1.0f,0.0f,//D
  
  /*------------------三角形DBF----------------------*/
 0.5f,  0.5f,  0.5f,  0.0f,1.0f,0.0f,//D
 -0.5f,  0.5f,  0.5f,  0.0f,1.0f,0.0f,//B
 -0.5f, -0.5f,  0.5f,  0.0f,1.0f,0.0f,//F
  
  /*------------------三角形BAE----------------------*/
 -0.5f,  0.5f,  0.5f,  0.0f,0.0f,1.0f,//B
 -0.5f,  0.5f, -0.5f,  0.0f,0.0f,1.0f,//A
 -0.5f, -0.5f, -0.5f,  0.0f,0.0f,1.0f,//E
  
  /*------------------三角形EFB----------------------*/
 -0.5f, -0.5f, -0.5f,  0.0f,0.0f,1.0f,//E
 -0.5f, -0.5f,  0.5f,  0.0f,0.0f,1.0f,//F
 -0.5f,  0.5f,  0.5f,  0.0f,0.0f,1.0f,//B
  
  /*------------------三角形DCG----------------------*/
 0.5f,  0.5f,  0.5f,  0.5f,0.0f,0.0f,//D
 0.5f,  0.5f, -0.5f,  0.5f,0.0f,0.0f,//C
 0.5f, -0.5f, -0.5f,  0.5f,0.0f,0.0f,//G
  
  /*------------------三角形GHD----------------------*/
 0.5f, -0.5f, -0.5f,  0.5f,0.0f,0.0f,//G
 0.5f, -0.5f,  0.5f,  0.5f,0.0f,0.0f,//H
 0.5f,  0.5f,  0.5f,  0.5f,0.0f,0.0f,//D
  
  /*------------------三角形EGH----------------------*/
 -0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,//E
 0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,//G
 0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,//H
  
  /*------------------三角形HFE----------------------*/
 0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,//H
 -0.5f, -0.5f,  0.5f,  0.0f,0.5f,0.0f,//F
 -0.5f, -0.5f, -0.5f,  0.0f,0.5f,0.0f,//E
  
  /*------------------三角形ACD----------------------*/
 -0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f,//A
 0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f,//C
 0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,//D
  
  /*------------------三角形DBA----------------------*/
 0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,//D
 -0.5f,  0.5f,  0.5f,  0.0f,0.0f,0.5f,//B
 -0.5f,  0.5f, -0.5f,  0.0f,0.0f,0.5f//A
};

3.EBO表示法

如果用EBO的话，vertices数组和之前不一样的地方就是重复的点不需要再写出来，写一行，然后记录他在数组中的位置（哪一行）。
再新开一个indices数组，indices数组中的每个数字，对应的是之前vertice数组中的点（之前记录的位置），每一行表示一个三角形。具体代码如下：

float vertices[] = {
 
        -0.5f,0.5f,-0.5f,   0.0f, 0.0f, 0.0f,//点A 0
        -0.5f,0.5f,0.5f,    0.0f, 0.0f, 1.0f,//点B 1
        0.5f,0.5f,-0.5f,    0.0f, 1.0f, 0.0f,//点C 2
        0.5f,0.5f,0.5f,     0.0f, 1.0f, 1.0f,//点D 3
         
        -0.5f,-0.5f,-0.5f,  1.0f, 0.0f, 0.0f,//点E 4
        -0.5f,-0.5f,0.5f,   1.0f, 0.0f, 1.0f,//点F 5
        0.5f,-0.5f,-0.5f,   1.0f, 1.0f, 0.0f,//点G 6
        0.5f,-0.5f,0.5f,    1.0f, 1.0f, 1.0f//点H 7
 
     };
 
    unsigned int indices[] = {
        /*上面ABC,BCD*/
        0,1,2,
        1,2,3,
 
        /*下面EFG,FGH*/
        4,5,6,
        5,6,7,
        /*左侧面ABF,AEF*/
        0,1,5,
        0,4,5,
        /*右侧面CDH,CGH*/
        2,3,7,
        2,6,7,
        /*前面ACG,AEG*/
        0,2,6,
        0,4,6,
        /*后面BFH,BDH*/
        1,5,7,
        1,3,7
    };

参考文章：

https://www.jianshu.com/p/12b0c198c2e0
https://blog.csdn.net/dcrmg/article/details/53556664