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

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

namespace TheLabs.Shapes;

public class Cylinder
{
    // Vertex Array Object, Vertex Buffer Object, Element Buffer Object
    private int _vao;
    private int _vbo;
    private int _ebo;
    private int _vertexCount;
    private Circle _topCircle;
    private Circle _bottomCircle;
    private float _radius = 0.5f;
    private float _height = 1.0f;
    
    private float[] _vertices =
    {
    };

    private uint[] _indices =
    {

    };
    public Cylinder()
    {
        // The number of vertices to draw
        _vertexCount = _indices.Length;
        _topCircle = new Circle(0.5f, 10, new Vector4(1f, 1f, 0f, 1f));
        _bottomCircle = new Circle(-0.5f, 10, new Vector4(1f, 0f, 0f, 1f));
        GenerateCylinder(10);
        
    }

    private void GenerateCylinder(int segments)
    {
        var vertices = new List<float>();
        var indices = new List<uint>();

        for (int i = 0; i < segments; i++)
        {
            float angle1 = 2.0f * MathF.PI * i / segments;
            float angle2 = 2.0f * MathF.PI * ((i + 1) % segments) / segments;

            float x1 = _radius * MathF.Cos(angle1);
            float y1 = _radius * MathF.Sin(angle1);
            float x2 = _radius * MathF.Cos(angle2);
            float y2 = _radius * MathF.Sin(angle2);

            float zTop = _height / 2f;
            float zBottom = -_height / 2f;

            Vector4 sideColor = new Vector4(0f, 1f, 1f, 1f); // side color

            // Add vertices: top1, bottom1, top2, bottom2
            int top1Index = vertices.Count / 7;
            vertices.AddRange(new float[] { x1, y1, zTop, sideColor.X, sideColor.Y, sideColor.Z, sideColor.W });

            int bottom1Index = vertices.Count / 7;
            vertices.AddRange(new float[] { x1, y1, zBottom, sideColor.X, sideColor.Y, sideColor.Z, sideColor.W });

            int top2Index = vertices.Count / 7;
            vertices.AddRange(new float[] { x2, y2, zTop, sideColor.X, sideColor.Y, sideColor.Z, sideColor.W });

            int bottom2Index = vertices.Count / 7;
            vertices.AddRange(new float[] { x2, y2, zBottom, sideColor.X, sideColor.Y, sideColor.Z, sideColor.W });

            // First triangle
            indices.Add((uint)top1Index);
            indices.Add((uint)bottom1Index);
            indices.Add((uint)top2Index);

            // Second triangle
            indices.Add((uint)top2Index);
            indices.Add((uint)bottom1Index);
            indices.Add((uint)bottom2Index);
        }

        _vertices = vertices.ToArray();
        _indices = indices.ToArray();
        _vertexCount = indices.Count;
        
        // OpenGL setup
        _vao = GL.GenVertexArray();
        _vbo = GL.GenBuffer();
        _ebo = GL.GenBuffer();

        GL.BindVertexArray(_vao);

        GL.BindBuffer(BufferTarget.ArrayBuffer, _vbo);
        GL.BufferData(BufferTarget.ArrayBuffer, vertices.Count * sizeof(float), vertices.ToArray(), BufferUsageHint.StaticDraw);

        GL.BindBuffer(BufferTarget.ElementArrayBuffer, _ebo);
        GL.BufferData(BufferTarget.ElementArrayBuffer, indices.Count * sizeof(uint), indices.ToArray(), BufferUsageHint.StaticDraw);

        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 void Draw(Shader shader, Matrix4 model, Matrix4 view, Matrix4 projection)
    {
        shader.SetMatrix4("model", model);
        // Set the matrices in the shader
        int modelLoc = GL.GetUniformLocation(shader.Handle, "model");
        int viewLoc = GL.GetUniformLocation(shader.Handle, "view");
        int projLoc = GL.GetUniformLocation(shader.Handle, "projection");
            
        // Send the matrices to the shader
        GL.UniformMatrix4(modelLoc, false, ref model);
        GL.UniformMatrix4(viewLoc, false, ref view);
        GL.UniformMatrix4(projLoc, false, ref projection);
        
        GL.BindVertexArray(_vao);
        GL.DrawElements(PrimitiveType.Triangles, _indices.Length, DrawElementsType.UnsignedInt, 0);
        _topCircle.Draw(shader, view, projection, model);
        _bottomCircle.Draw(shader, view, projection, model);
    }
    
    public void Dispose()
    {
        GL.DeleteBuffer(_vbo);
        GL.DeleteBuffer(_ebo);
        GL.DeleteVertexArray(_vao);
    }
}