First knowledge of OpenGL (2) compilation shaders

step1. Create a shader object

use ID To quote , Save this vertex shader as unsigned int,

unsigned int vertexShader;
vertexShader = glCreateShader(GL_VERTEX_SHADER);

. glCreateShader Create shader .

Parameters : Shader type .eg. Vertex shader , The parameters passed are GL_VERTEX_SHADER.

step2. Attach the shader source code to the shader object and compile

const char *vertexShaderSource = "#version 330 core\n"
    "layout (location = 0) in vec3 aPos;\n"
    "void main()\n"
    "{\n"
    " gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
    "}\0";

glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);

glShaderSource function
The first parameter : The shader object to compile .
The second parameter : Specifies the number of source strings passed , There's only one .
The third parameter : Vertex shader real source code
Fourth parameter : Set to NULL.

step3. Check the compilation results

Detect call glCompileShader Whether the post compilation is successful , If it doesn't succeed , You will also want to know what the mistake is , So you can fix them . Detecting compile time errors can be achieved by the following code ：

int  success;
char infoLog[512];
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);

First, we define an integer variable to indicate whether the compilation was successful , It also defines a storage error message （ If any ） The container of . And then we use glGetShaderiv Check if the compilation is successful . If compilation fails , We will use glGetShaderInfoLog Get error messages , And print it .

if(!success)
{
    
    glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
    std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
}

If no errors are detected during compilation , The vertex shader is compiled successfully