0.一般來說vertex shader處理頂點座標，然後向後傳輸，經過光柵化之後，傳給fragment shader，其負責顏色、紋理、光照等等。

前者處理之後變成裁剪座標系（三維），光柵化之後一般認為變成二維的裝置座標系

1.每個頂點有多個屬性時的頂點著色器：

 1 #version 330 core
 2 layout (location = 0) in vec3 aPos;
 3 layout (location = 1) in vec3 aColor;
 4 layout (location = 2) in vec2 aTexCoord;
 5 
 6 out vec3 ourColor;
 
 7 out vec2 TexCoord;
 8 
 9 void main()
10 {
11     gl_Position = vec4(aPos, 1.0);
12     ourColor = aColor;
13     TexCoord = aTexCoord;
14 }

2.只處理紋理的片元著色器：

 1 #version 330 core
 2 out vec4 FragColor;
 3 
 4 in vec3 ourColor;
 5 in vec2 TexCoord;
 6 
 7 uniform sampler2D ourTexture;
 
 8 
 9 void main()
10 {
11     FragColor = texture(ourTexture, TexCoord);
12 }

3.將2中的紋理新增之後再加入頂點的顏色，片元著色器咋寫呢：

 1 #version 330 core
 2 out vec4 FragColor;
 3 
 4 in vec3 ourColor;
 5 in vec2 TexCoord;
 6 
 7 uniform sampler2D ourTexture;
 8 
 9 void main()
10 {
11     FragColor = texture(ourTexture, TexCoord);
 
12     FragColor = texture(ourTexture, TexCoord) * vec4(ourColor, 1.0);
13 }

4.渲染多個紋理咋辦呢？

 1 #version 330 core
 2 ...
 3 
 4 uniform sampler2D texture1;
 5 uniform sampler2D texture2;
 6 
 7 void main()
 8 {
 9     FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 0.2);
10 }