Added cylinder class

TheRepo/TheLabs/MyExampleWindow.cs

@@ -36,6 +36,7 @@ namespace TheLabs
 
         private Cube _cube;
         private Circle _circle;
+        private Cylinder _cylinder;
         private Shader _shader;
         private float _rotation;
 
@@ -58,6 +59,7 @@ namespace TheLabs
             // Create a cube
             _cube = new Cube();
             _circle = new Circle();
+            _cylinder = new Cylinder();
             // Use the shader program. This is similar to "activating" the shader program.
             _shader.Use();
             
@@ -93,8 +95,9 @@ namespace TheLabs
             GL.UniformMatrix4(projLoc, false, ref projection);
             
             // Draw the cube
-            _cube.Draw(_shader, model);
+            //_cube.Draw(_shader, model);
-            _circle.Draw(_shader, model);
+            //_circle.Draw(_shader, model);
+            _cylinder.Draw(_shader, model);
             SwapBuffers();
             GL.GetError();
         }

TheRepo/TheLabs/Shapes/Circle.cs

@@ -18,9 +18,10 @@ public class Circle
 
     };
     private int _maxVert = 100;
-    public Circle()
+    public Circle(float z = 0f, int segments = 100, Vector4? color = null)
     {
-        for (int i = 0; i <= _maxVert; i++)
+        Vector4 col = color ?? new Vector4(0f, 0f, 1f, 1f);
+        for (int i = 0; i <= segments; i++)
         {
 
             float angle = i * 2.0f * MathF.PI / _maxVert;
@@ -30,11 +31,11 @@ public class Circle
             Array.Resize(ref _vertices, _vertices.Length + 7);
             _vertices[^7] = x;
             _vertices[^6] = y;
-            _vertices[^5] = 0.0f;
+            _vertices[^5] = z;
-            _vertices[^4] = 1f;
+            _vertices[^4] = col.X;
-            _vertices[^3] = 0f;
+            _vertices[^3] = col.Y;
-            _vertices[^2] = 0f;
+            _vertices[^2] = col.Z;
-            _vertices[^1] = 1f;
+            _vertices[^1] = col.W;
 
         }
         // The Vertex Array Object
@@ -66,6 +67,10 @@ public class Circle
         GL.BindVertexArray(0);
     }
 
+    public float[] GetVertices()
+    {
+        return _vertices;
+    }
     public void Draw(Shader shader, Matrix4 matrix4)
     {
         shader.SetMatrix4("model", matrix4);

TheRepo/TheLabs/Shapes/Cylinder.cs

@@ -0,0 +1,124 @@
+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, 100, new Vector4(1f, 1f, 0f, 1f));
+        _bottomCircle = new Circle(-0.5f, 100, new Vector4(1f, 0f, 0f, 1f));
+        GenerateCylinder(101);
+        
+    }
+
+    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 matrix4)
+    {
+        shader.SetMatrix4("model", matrix4);
+        
+        GL.BindVertexArray(_vao);
+        GL.DrawElements(PrimitiveType.Triangles, _indices.Length, DrawElementsType.UnsignedInt, 0);
+        _topCircle.Draw(shader, matrix4);
+        _bottomCircle.Draw(shader, matrix4);
+    }
+    
+    public void Dispose()
+    {
+        GL.DeleteBuffer(_vbo);
+        GL.DeleteBuffer(_ebo);
+        GL.DeleteVertexArray(_vao);
+    }
+}