How can you create an OpenGL plot without relying on external libraries, starting from scratch?

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To create an OpenGL plot from scratch, follow these steps:

1. Initialize OpenGL: Initialize OpenGL by creating a GLFW window and setting up the OpenGL context.

2. Setting up the viewport: Set up the viewport using glViewport. This will define the region where the graphics will be rendered.

3. Create the data: Generate the data to plot. This can be done manually or by using a data set.

4. Create the vertex buffer: Create a vertex buffer object (VBO) to store the vertex data.

5. Create the shader program: Write the vertex shader and the fragment shader. The vertex shader will define the vertex attributes, and the fragment shader will define the colors for each vertex. Compile the shader program and link it to the application.

6. Draw the plot: Bind the vertex buffer object and enable the vertex attributes. Use the shader program to draw the plot using glDrawArrays.

7. Display the plot: Display the plot by swapping the buffers.

Here's an example code snippet to draw a simple plot:

// Create the vertex data
std::vector<float> data = {0.0f, 0.0f, 0.0f,
                           1.0f, 1.0f, 0.0f};

// Create the vertex buffer
GLuint vbo;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, data.size() * sizeof(float), data.data(), GL_STATIC_DRAW);

// Create the vertex shader
std::string vertexShaderSource = R"(
#version 330 core
layout (location = 0) in vec3 position;
void main()
{
    gl_Position = vec4(position.x, position.y, position.z, 1.0);
}
)";
GLuint vertexShader;
vertexShader = glCreateShader(GL_VERTEX_SHADER);
const char* vertexShaderCstr = vertexShaderSource.c_str();
glShaderSource(vertexShader, 1, &vertexShaderCstr, nullptr);
glCompileShader(vertexShader);

// Create the fragment shader
std::string fragmentShaderSource = R"(
#version 330 core
out vec4 FragColor;
void main()
{
    FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
)";
GLuint fragmentShader;
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
const char* fragmentShaderCstr = fragmentShaderSource.c_str();
glShaderSource(fragmentShader, 1, &fragmentShaderCstr, nullptr);
glCompileShader(fragmentShader);

// Create the shader program
GLuint shaderProgram;
shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);

// Draw the plot
glUseProgram(shaderProgram);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glDrawArrays(GL_LINE_STRIP, 0, 2);
glDisableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);

// Display the plot
glfwSwapBuffers(window);

This code will draw a simple line plot that goes from (0, 0) to (1, 1). The vertex shader only sets the position attribute, and the fragment shader sets the color to red. Note that this code is just a starting point, and more complex plots will require additional steps, such as setting up the projection and model matrices, handling user input, and adding lighting effects.