第一种方法：在绘制过程中通过uniform变量将颜色信息传给GPU:
1. 首先绘制程序定义变量：
GLuint oc;
2. 片段着色器中添加
uniform vec3 objectColor;
3. 模型绘制前（循环中）加上：
oc=glGetUniformLocation(renderingProgram,"objectColor");
4. 根据需要的颜色定义：
glm::vec3 objectColor(1.0f, 0.0f, 0.0f);
5. 将值传给uniform变量
glUniform3fv(oc,1,glm::value_ptr(objectColor));
这样，就能根据需要变换不同的颜色了。
也可以通过函数将颜色值放到顶点数组中，和顶点一起传送给GPU处理：
1. //函数用来将颜色值添加到坐标值+法向值后面；第一个变量是顶点数组，第二个是数组长度， 第三个是颜色信息，第四个容器用于输出
void appendColor(float * vertex,int vectexLen,float * color,vector<float> &vec)
{
//函数中如果要返回数组，需要定义成static（局部变量无法引用）
//但是这时候要求数组的维数固定,所以最好是将数组部分拿到函数外面
for(int m=0;m<vectexLen;m++)
{
vec.push_back(vertex[m]);
if((m+1)%6==0)
{
vec.push_back(color[0]);
vec.push_back(color[1]);
vec.push_back(color[2]);
}
}
}
//正方形有6个面，每个面有两个三角形，每个三角形有三个顶点，每个顶点有三个坐标
//有6*2*3*3=108个坐标值，加上法向坐标值，共有216个数值
float vertex[216]={
-1.0f,1.0f,-1.0f,0.0f,0.0f,-1.0f,
-1.0f,-1.0f,-1.0f,0.0f,0.0f,-1.0f,
1.0f,-1.0f,-1.0f,0.0f,0.0f,-1.0f,
1.0f,-1.0f,-1.0f,0.0f,0.0f,-1.0f,
1.0f,1.0f,-1.0f,0.0f,0.0f,-1.0f,
-1.0f,1.0f,-1.0f,0.0f,0.0f,-1.0f,
1.0f,-1.0f,-1.0f,1.0f,0.0f,0.0f,
1.0f,-1.0f,1.0f,1.0f,0.0f,0.0f,
1.0f,1.0f,-1.0f,1.0f,0.0f,0.0f,
1.0f,-1.0f,1.0f,1.0f,0.0f,0.0f,
1.0f,1.0f,1.0f,1.0f,0.0f,0.0f,
1.0f,1.0f,-1.0f,1.0f,0.0f,0.0f,
1.0f,-1.0f,1.0f,0.0f,0.0f,1.0f,
-1.0f,-1.0f,1.0f,0.0f,0.0f,1.0f,
1.0f,1.0f,1.0f,0.0f,0.0f,1.0f,
-1.0f,-1.0f,1.0f,0.0f,0.0f,1.0f,
-1.0f,1.0f,1.0f,0.0f,0.0f,1.0f,
1.0f,1.0f,1.0f,0.0f,0.0f,1.0f,
-1.0f,-1.0f,1.0f,-1.0f,0.0f,0.0f,
-1.0f,-1.0f,-1.0f,-1.0f,0.0f,0.0f,
-1.0f,1.0f,1.0f,-1.0f,0.0f,0.0f,
-1.0f,-1.0f,-1.0f,-1.0f,0.0f,0.0f,
-1.0f,1.0f,-1.0f,-1.0f,0.0f,0.0f,
-1.0f,1.0f,1.0f,-1.0f,0.0f,0.0f,
-1.0f,-1.0f,1.0f,0.0f,-1.0f,0.0f,
1.0f,-1.0f,1.0f,0.0f,-1.0f,0.0f,
1.0f,-1.0f,-1.0f,0.0f,-1.0f,0.0f,
1.0f,-1.0f,-1.0f,0.0f,-1.0f,0.0f,
-1.0f,-1.0f,-1.0f,0.0f,-1.0f,0.0f,
-1.0f,-1.0f,1.0f,0.0f,-1.0f,0.0f,
-1.0f,1.0f,-1.0f,0.0f,1.0f,0.0f,
1.0f,1.0f,-1.0f,0.0f,1.0f,0.0f,
1.0f,1.0f,1.0f,0.0f,1.0f,0.0f,
1.0f,1.0f,1.0f,0.0f,1.0f,0.0f,
-1.0f,1.0f,1.0f,0.0f,1.0f,0.0f,
-1.0f,1.0f,-1.0,0.0f,1.0f,0.0f
};
//下面这段程序使用容器在顶点后面加上颜色数据，然后再将数据转为数组
float color1[]={0.0f,0.0f,1.0f};
int lenver=sizeof(vertex)/sizeof(float);
vector<float> vec1;
appendColor(vertex,lenver,color1,vec1);
int n = vec1.size();
float arr1[n];
for(int i=0; i<n; i++){
arr1[i] = vec1[i];
}
2. 在顶点着色器中定义输入变量：
layout (location=0) in vec3 position;
layout (location=1) in vec3 innormal;
layout (location=2) in vec3 VertexColor;
3. 解释并缓存数据
//启用指定属性
glEnableVertexAttribArray(0);
//数据解释：顶点着色器中location的值;顶点属性的维数;数据的类型;是否数据被标准化;步长,0-让OpenGL自己去识别;起始位置的偏移量
glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,9*sizeof(float),(void*)0);
//启用指定属性
glEnableVertexAttribArray(1);
glVertexAttribPointer(1,3,GL_FLOAT,GL_FALSE,9*sizeof(float),(void*)(3*sizeof(float)));
//启用指定属性
glEnableVertexAttribArray(2);
glVertexAttribPointer(2,3,GL_FLOAT,GL_FALSE,9*sizeof(float),(void*)(6*sizeof(float)));
glBufferData(GL_ARRAY_BUFFER, sizeof(arr1), arr1, GL_STATIC_DRAW);
4. 直接绘制图形
glBindVertexArray(vao[0]);
glDrawArrays(GL_TRIANGLES,0,36);
glBindVertexArray(0);
截图中的图片经过了渲染，有光照效果，否则看上去边角不清楚。
