551455-graphics-programming-2526-the-repo-Zyb3rWolfi/TheRepo/TheLabs/Shapes/Circle.cs

using LearnOpenTK.Common;
using OpenTK.Graphics.OpenGL4;
using OpenTK.Mathematics;

namespace TheLabs.Shapes;

public class Circle
{
    // Vertex Array Object, Vertex Buffer Object, Element Buffer Object
    private int _vao;
    private int _vbo;
    private int _ebo;
    private int _vertexCount;
    
    private readonly float[] _vertices =
    {


    };
    private int _maxVert = 100;
    public Circle(float z = 0f, int segments = 100, Vector4? color = null)
    {
        Vector4 col = color ?? new Vector4(0f, 0f, 1f, 1f);
        for (int i = 0; i <= segments; i++)
        {

            float angle = i * 2.0f * MathF.PI / _maxVert;
            float x = 0.5f * MathF.Cos(angle);
            float y = 0.5f * MathF.Sin(angle);
            
            Array.Resize(ref _vertices, _vertices.Length + 7);
            _vertices[^7] = x;
            _vertices[^6] = y;
            _vertices[^5] = z;
            _vertices[^4] = col.X;
            _vertices[^3] = col.Y;
            _vertices[^2] = col.Z;
            _vertices[^1] = col.W;

        }
        // The Vertex Array Object
        // This stores the confifuration of vertex atributes
        _vao = GL.GenVertexArray(); 
        // The Vertex Buffer Object
        // This stores the actual vertex data e.g. positions, colors, normals, texture coordinates
        _vbo = GL.GenBuffer();
        
        // We bind the VAO
        GL.BindVertexArray(_vao);
        GL.BindBuffer(BufferTarget.ArrayBuffer, _vbo); // Specifying the type of buffer
        // Uploading the vertex data to the GPU
        GL.BufferData(BufferTarget.ArrayBuffer, _vertices.Length * sizeof(float), _vertices, BufferUsageHint.StaticDraw);
        
        // We tell opengl how to interpret the vertex data.
        // The Location 0 corresponds to the layout(location = 0) in the vertex shader
        // How many components (x, y, z) -> 3
        // Data type -> float
        // Not normalized
        // The Stride -> The total size of a vertex (in bytes)
        // The offset -> The position data starts at the beginning of the vertex data so 0
        var stride = 7 * sizeof(float);
        GL.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, stride, 0);
        GL.EnableVertexAttribArray(0);
        GL.VertexAttribPointer(1, 4, VertexAttribPointerType.Float, false, stride, 3 * sizeof(float));
        GL.EnableVertexAttribArray(1);
        
        GL.BindVertexArray(0);
    }

    public float[] GetVertices()
    {
        return _vertices;
    }
    public void Draw(Shader shader, Matrix4 matrix4)
    {
        shader.SetMatrix4("model", matrix4);
        GL.BindVertexArray(_vao);
        GL.DrawArrays(PrimitiveType.TriangleFan, 0, _vertices.Length / 7);

    }
    
    public void Dispose()
    {
        GL.DeleteBuffer(_vbo);
        GL.DeleteBuffer(_ebo);
        GL.DeleteVertexArray(_vao);
    }
}