opengl颜色处理，如何用OpenGL显示图片

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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。

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