basic example with rotating textured cube

Examples/BasicExamples/RotatingTexturedCubeExample.cs

@@ -0,0 +1,134 @@
+using System;
+using System.Diagnostics;
+using System.Drawing;
+using Examples.Shaders;
+using ObjectTK.Buffers;
+using ObjectTK.Shaders;
+using ObjectTK.Textures;
+using ObjectTK.Tools.Shapes;
+using OpenTK;
+using OpenTK.Graphics.OpenGL;
+using OpenTK.Input;
+
+namespace Examples.BasicExamples
+{
+    [ExampleProject("Rotating textured cube rendering")]
+    public class RotatingTexturedCubeExample
+        : ExampleWindow
+    {
+        private Texture2D _texture;
+
+        private SimpleTextureProgram _textureProgram;
+
+        private TexturedCube _cube;
+        private VertexArray _cubeVao;
+
+        private Matrix4 _baseView;
+        private Matrix4 _objectView;
+
+        private Vector3[] _rotateVectors = new[] { Vector3.Zero, Vector3.UnitX, Vector3.UnitY, Vector3.UnitZ, Vector3.One };
+        private const int _defaultRotateIndex = 4;
+
+        private int _rotateIndex = _defaultRotateIndex;
+        private readonly Stopwatch _stopwatch = new Stopwatch();
+
+        public RotatingTexturedCubeExample()
+        {
+            Load += OnLoad;
+            RenderFrame += OnRenderFrame;
+            KeyDown += OnKeyDown;
+        }
+
+        private void OnKeyDown(object sender, KeyboardKeyEventArgs e)
+        {
+            switch (e.Key)
+            {
+                case Key.R:
+                    _objectView = _baseView = Matrix4.Identity;
+                    _rotateIndex = _defaultRotateIndex;
+                    _stopwatch.Restart();
+                    break;
+
+                case Key.Space:
+                    _baseView = _objectView;
+                    _rotateIndex = (_rotateIndex + 1) % _rotateVectors.Length;
+                    _stopwatch.Restart();
+                    break;
+
+                case Key.Number0:
+                case Key.Number1:
+                case Key.Number2:
+                case Key.Number3:
+                case Key.Number4:
+                    _baseView = _objectView;
+                    _rotateIndex = (e.Key - Key.Number0) % _rotateVectors.Length;
+                    _stopwatch.Restart();
+                    break;
+            }
+        }
+
+        private void OnLoad(object sender, EventArgs e)
+        {
+            // load texture from file
+            using (var bitmap = new Bitmap("Data/Textures/crate.png"))
+            {
+                BitmapTexture.CreateCompatible(bitmap, out _texture);
+                _texture.LoadBitmap(bitmap);
+            }
+
+            // initialize shaders
+            _textureProgram = ProgramFactory.Create<SimpleTextureProgram>();
+
+            // initialize cube object and base view matrix
+            _objectView = _baseView = Matrix4.Identity;
+
+            // initialize demonstration geometry
+            _cube = new TexturedCube();
+            _cube.UpdateBuffers();
+
+            // set up vertex attributes for the quad
+            _cubeVao = new VertexArray();
+            _cubeVao.Bind();
+            _cubeVao.BindAttribute(_textureProgram.InPosition, _cube.VertexBuffer);
+            _cubeVao.BindAttribute(_textureProgram.InTexCoord, _cube.TexCoordBuffer);
+
+            // Enable culling, our cube vertices are defined inside out, so we flip them
+            GL.Enable(EnableCap.CullFace);
+            GL.CullFace(CullFaceMode.Back);
+
+            // initialize camera position
+            Camera.DefaultState.Position = new Vector3(0, 0, 4);
+            Camera.ResetToDefault();
+
+            // set nice clear color
+            GL.ClearColor(Color.MidnightBlue);
+
+            _stopwatch.Restart();
+        }
+
+        private void OnRenderFrame(object sender, OpenTK.FrameEventArgs e)
+        {
+            // set up viewport
+            GL.Viewport(0, 0, Width, Height);
+            GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
+            SetupPerspective();
+
+            // determinate object view rotation vectors and apply them
+            _objectView = _baseView;
+            var rotation = _rotateVectors[_rotateIndex];
+            if (rotation != Vector3.Zero)
+                _objectView *= Matrix4.CreateFromAxisAngle(_rotateVectors[_rotateIndex], (float)(_stopwatch.Elapsed.TotalSeconds * 1.0));
+
+            // set transformation matrix
+            _textureProgram.Use();
+            _textureProgram.ModelViewProjectionMatrix.Set(_objectView * ModelView * Projection);
+
+            // render cube with texture
+            _cubeVao.Bind();
+            _cubeVao.DrawArrays(_cube.DefaultMode, 0, _cube.VertexBuffer.ElementCount);
+
+            // swap buffers
+            SwapBuffers();
+        }
+    }
+}

Examples/Examples.csproj

@@ -50,6 +50,7 @@
     <Compile Include="AdvancedExamples\LoaderDDS.cs" />
     <Compile Include="AdvancedExamples\LoaderStatics.cs" />
     <Compile Include="AdvancedExamples\ParallaxMappingExample.cs" />
+    <Compile Include="BasicExamples\RotatingTexturedCubeExample.cs" />
     <Compile Include="BasicExamples\TextureGridExample.cs" />
     <Compile Include="BasicExamples\SkyboxExample.cs" />
     <Compile Include="ExampleProjectAttribute.cs" />
@@ -106,6 +107,7 @@
     <Content Include="Data\Textures\city3.jpg" />
     <Content Include="Data\Textures\city4.jpg" />
     <Content Include="Data\Textures\city5.jpg" />
+    <Content Include="Data\Textures\crate.png" />
     <Content Include="Data\Textures\empty.png" />
     <Content Include="Data\Textures\flag.png" />
     <Content Include="Data\Textures\mine.png" />

ObjectTK.Tools/ObjectTK.Tools.csproj

@@ -61,6 +61,7 @@
     <Compile Include="Shapes\Quad.cs" />
     <Compile Include="Shapes\Rect.cs" />
     <Compile Include="Shapes\Shape.cs" />
+    <Compile Include="Shapes\TexturedCube.cs" />
     <Compile Include="Shapes\TexturedQuad.cs" />
     <Compile Include="Shapes\TexturedShape.cs" />
   </ItemGroup>

ObjectTK.Tools/Shapes/TexturedCube.cs

@@ -0,0 +1,45 @@
+//
+// TexturedCube.cs
+//
+// Copyright (C) 2018 OpenTK
+//
+// This software may be modified and distributed under the terms
+// of the MIT license. See the LICENSE file for details.
+//
+
+using OpenTK;
+using OpenTK.Graphics.OpenGL;
+using System.Linq;
+
+namespace ObjectTK.Tools.Shapes
+{
+    public class TexturedCube
+        : TexturedShape
+    {
+        public TexturedCube()
+        {
+            DefaultMode = PrimitiveType.Triangles;
+
+            var quad_uv_map = new[]
+            {
+                new Vector2(0, 0),
+                new Vector2(0, 1),
+                new Vector2(1, 1),
+                new Vector2(1, 1),
+                new Vector2(1, 0),
+                new Vector2(0, 0),
+            };
+
+            // use default cube
+            using (var cube = new Cube())
+            {
+                // Cube uses indexed vertices, TexturedShape assumes a flat vertices array
+                // So we need to assemble the missing vertices ourself
+                Vertices = cube.Indices.Select(idx => cube.Vertices[idx]).ToArray();
+
+                // Use predefined uv texture mapping for vertices
+                TexCoords = Enumerable.Range(0, Vertices.Length).Select(i => quad_uv_map[i % quad_uv_map.Length]).ToArray();
+            }
+        }
+    }
+}