First knowledge of OpenGL (3) fragment shader

step1. Fragment Shader

Calculate the final color output of pixels . Fragment shaders require only one output variable , This variable is a 4 Component vector , It represents the final output color , We should calculate it ourselves .

#version 330 core
out vec4 FragColor;

void main()
{
    
    FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);
} 

Declare that the output variable can use out keyword , Here we call it FragColor.

step2. Compiling fragment shaders

Similar to vertex shaders , Use GL_FRAGMENT_SHADER Constant as shader type ：

unsigned int fragmentShader;
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);