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

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

namespace TheLabs.Shapes;

public class Cube
{
    // Vertex Array Object, Vertex Buffer Object, Element Buffer Object
    private int _vao;
    private int _vbo;
    private int _ebo;
    private int _vertexCount;
    
    private readonly float[] _cubevertices =
    {
        // Position           // Color (RGBA)
        // Front face (z = +0.5)
        -0.5f, -0.5f,  0.5f,  1f, 0f, 0f, 1f, // Bottom-left
        0.5f, -0.5f,  0.5f,  1f, 0f, 0f, 1f, // Bottom-right
        0.5f,  0.5f,  0.5f,  0f, 0f, 0f, 1f, // Top-right
        -0.5f,  0.5f,  0.5f,  1f, 0f, 0f, 1f, // Top-left

        // Back face (z = -0.5)
        -0.5f, -0.5f, -0.5f,  1f, 0f, 1f, 1f, // Bottom-left
        0.5f, -0.5f, -0.5f,  0f, 1f, 1f, 1f, // Bottom-right
        0.5f,  0.5f, -0.5f,  1f, 1f, 1f, 1f, // Top-right
        -0.5f,  0.5f, -0.5f,  0.5f, 0.5f, 0.5f, 1f // Top-left
    };
    private readonly uint[] _cubeIndices =
    {
        // Front face
        0, 1, 2,
        2, 3, 0,

        // Back face
        4, 5, 6,
        6, 7, 4,

        // Left face
        4, 0, 3,
        3, 7, 4,

        // Right face
        1, 5, 6,
        6, 2, 1,

        // Top face
        3, 2, 6,
        6, 7, 3,

        // Bottom face
        4, 5, 1,
        1, 0, 4
    };

    public Cube()
    {
        // The number of vertices to draw
        _vertexCount = _cubeIndices.Length;
        // 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();
        // The Element Buffer Object, stores the indices for indexed drawing
        _ebo = 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, _cubevertices.Length * sizeof(float), _cubevertices, BufferUsageHint.StaticDraw);
        
        // Now we set up the EBO
        GL.BindBuffer(BufferTarget.ElementArrayBuffer, _ebo);
        // Uploading the index data to the GPU
        GL.BufferData(BufferTarget.ElementArrayBuffer, _cubeIndices.Length * sizeof(uint), _cubeIndices, 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 void Draw(Shader shader, Matrix4 matrix4)
    {
        shader.SetMatrix4("model", matrix4);
        
        GL.BindVertexArray(_vao);
        GL.DrawElements(PrimitiveType.Triangles, _cubeIndices.Length, DrawElementsType.UnsignedInt, 0);
        
    }
    
    public void Dispose()
    {
        GL.DeleteBuffer(_vbo);
        GL.DeleteBuffer(_ebo);
        GL.DeleteVertexArray(_vao);
    }
}