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    • By Fadey Duh
      Good evening everyone!

      I was wondering if there is something equivalent of  GL_NV_blend_equation_advanced for AMD?
      Basically I'm trying to find more compatible version of it.

      Thank you!
    • By Jens Eckervogt
      Hello guys, 
       
      Please tell me! 
      How do I know? Why does wavefront not show for me?
      I already checked I have non errors yet.
      using OpenTK; using System.Collections.Generic; using System.IO; using System.Text; namespace Tutorial_08.net.sourceskyboxer { public class WaveFrontLoader { private static List<Vector3> inPositions; private static List<Vector2> inTexcoords; private static List<Vector3> inNormals; private static List<float> positions; private static List<float> texcoords; private static List<int> indices; public static RawModel LoadObjModel(string filename, Loader loader) { inPositions = new List<Vector3>(); inTexcoords = new List<Vector2>(); inNormals = new List<Vector3>(); positions = new List<float>(); texcoords = new List<float>(); indices = new List<int>(); int nextIdx = 0; using (var reader = new StreamReader(File.Open("Contents/" + filename + ".obj", FileMode.Open), Encoding.UTF8)) { string line = reader.ReadLine(); int i = reader.Read(); while (true) { string[] currentLine = line.Split(); if (currentLine[0] == "v") { Vector3 pos = new Vector3(float.Parse(currentLine[1]), float.Parse(currentLine[2]), float.Parse(currentLine[3])); inPositions.Add(pos); if (currentLine[1] == "t") { Vector2 tex = new Vector2(float.Parse(currentLine[1]), float.Parse(currentLine[2])); inTexcoords.Add(tex); } if (currentLine[1] == "n") { Vector3 nom = new Vector3(float.Parse(currentLine[1]), float.Parse(currentLine[2]), float.Parse(currentLine[3])); inNormals.Add(nom); } } if (currentLine[0] == "f") { Vector3 pos = inPositions[0]; positions.Add(pos.X); positions.Add(pos.Y); positions.Add(pos.Z); Vector2 tc = inTexcoords[0]; texcoords.Add(tc.X); texcoords.Add(tc.Y); indices.Add(nextIdx); ++nextIdx; } reader.Close(); return loader.loadToVAO(positions.ToArray(), texcoords.ToArray(), indices.ToArray()); } } } } } And It have tried other method but it can't show for me.  I am mad now. Because any OpenTK developers won't help me.
      Please help me how do I fix.

      And my download (mega.nz) should it is original but I tried no success...
      - Add blend source and png file here I have tried tried,.....  
       
      PS: Why is our community not active? I wait very longer. Stop to lie me!
      Thanks !
    • By codelyoko373
      I wasn't sure if this would be the right place for a topic like this so sorry if it isn't.
      I'm currently working on a project for Uni using FreeGLUT to make a simple solar system simulation. I've got to the point where I've implemented all the planets and have used a Scene Graph to link them all together. The issue I'm having with now though is basically the planets and moons orbit correctly at their own orbit speeds.
      I'm not really experienced with using matrices for stuff like this so It's likely why I can't figure out how exactly to get it working. This is where I'm applying the transformation matrices, as well as pushing and popping them. This is within the Render function that every planet including the sun and moons will have and run.
      if (tag != "Sun") { glRotatef(orbitAngle, orbitRotation.X, orbitRotation.Y, orbitRotation.Z); } glPushMatrix(); glTranslatef(position.X, position.Y, position.Z); glRotatef(rotationAngle, rotation.X, rotation.Y, rotation.Z); glScalef(scale.X, scale.Y, scale.Z); glDrawElements(GL_TRIANGLES, mesh->indiceCount, GL_UNSIGNED_SHORT, mesh->indices); if (tag != "Sun") { glPopMatrix(); } The "If(tag != "Sun")" parts are my attempts are getting the planets to orbit correctly though it likely isn't the way I'm meant to be doing it. So I was wondering if someone would be able to help me? As I really don't have an idea on what I would do to get it working. Using the if statement is truthfully the closest I've got to it working but there are still weird effects like the planets orbiting faster then they should depending on the number of planets actually be updated/rendered.
    • By Jens Eckervogt
      Hello everyone, 
      I have problem with texture
      using System; using OpenTK; using OpenTK.Input; using OpenTK.Graphics; using OpenTK.Graphics.OpenGL4; using System.Drawing; using System.Reflection; namespace Tutorial_05 { class Game : GameWindow { private static int WIDTH = 1200; private static int HEIGHT = 720; private static KeyboardState keyState; private int vaoID; private int vboID; private int iboID; private Vector3[] vertices = { new Vector3(-0.5f, 0.5f, 0.0f), // V0 new Vector3(-0.5f, -0.5f, 0.0f), // V1 new Vector3(0.5f, -0.5f, 0.0f), // V2 new Vector3(0.5f, 0.5f, 0.0f) // V3 }; private Vector2[] texcoords = { new Vector2(0, 0), new Vector2(0, 1), new Vector2(1, 1), new Vector2(1, 0) }; private int[] indices = { 0, 1, 3, 3, 1, 2 }; private string vertsrc = @"#version 450 core in vec3 position; in vec2 textureCoords; out vec2 pass_textureCoords; void main(void) { gl_Position = vec4(position, 1.0); pass_textureCoords = textureCoords; }"; private string fragsrc = @"#version 450 core in vec2 pass_textureCoords; out vec4 out_color; uniform sampler2D textureSampler; void main(void) { out_color = texture(textureSampler, pass_textureCoords); }"; private int programID; private int vertexShaderID; private int fragmentShaderID; private int textureID; private Bitmap texsrc; public Game() : base(WIDTH, HEIGHT, GraphicsMode.Default, "Tutorial 05 - Texturing", GameWindowFlags.Default, DisplayDevice.Default, 4, 5, GraphicsContextFlags.Default) { } protected override void OnLoad(EventArgs e) { base.OnLoad(e); CursorVisible = true; GL.GenVertexArrays(1, out vaoID); GL.BindVertexArray(vaoID); GL.GenBuffers(1, out vboID); GL.BindBuffer(BufferTarget.ArrayBuffer, vboID); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(vertices.Length * Vector3.SizeInBytes), vertices, BufferUsageHint.StaticDraw); GL.GenBuffers(1, out iboID); GL.BindBuffer(BufferTarget.ElementArrayBuffer, iboID); GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(indices.Length * sizeof(int)), indices, BufferUsageHint.StaticDraw); vertexShaderID = GL.CreateShader(ShaderType.VertexShader); GL.ShaderSource(vertexShaderID, vertsrc); GL.CompileShader(vertexShaderID); fragmentShaderID = GL.CreateShader(ShaderType.FragmentShader); GL.ShaderSource(fragmentShaderID, fragsrc); GL.CompileShader(fragmentShaderID); programID = GL.CreateProgram(); GL.AttachShader(programID, vertexShaderID); GL.AttachShader(programID, fragmentShaderID); GL.LinkProgram(programID); // Loading texture from embedded resource texsrc = new Bitmap(Assembly.GetEntryAssembly().GetManifestResourceStream("Tutorial_05.example.png")); textureID = GL.GenTexture(); GL.BindTexture(TextureTarget.Texture2D, textureID); GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)All.Linear); GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)All.Linear); GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, texsrc.Width, texsrc.Height, 0, PixelFormat.Bgra, PixelType.UnsignedByte, IntPtr.Zero); System.Drawing.Imaging.BitmapData bitmap_data = texsrc.LockBits(new Rectangle(0, 0, texsrc.Width, texsrc.Height), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppRgb); GL.TexSubImage2D(TextureTarget.Texture2D, 0, 0, 0, texsrc.Width, texsrc.Height, PixelFormat.Bgra, PixelType.UnsignedByte, bitmap_data.Scan0); texsrc.UnlockBits(bitmap_data); GL.Enable(EnableCap.Texture2D); GL.BufferData(BufferTarget.TextureBuffer, (IntPtr)(texcoords.Length * Vector2.SizeInBytes), texcoords, BufferUsageHint.StaticDraw); GL.BindAttribLocation(programID, 0, "position"); GL.BindAttribLocation(programID, 1, "textureCoords"); } protected override void OnResize(EventArgs e) { base.OnResize(e); GL.Viewport(0, 0, ClientRectangle.Width, ClientRectangle.Height); } protected override void OnUpdateFrame(FrameEventArgs e) { base.OnUpdateFrame(e); keyState = Keyboard.GetState(); if (keyState.IsKeyDown(Key.Escape)) { Exit(); } } protected override void OnRenderFrame(FrameEventArgs e) { base.OnRenderFrame(e); // Prepare for background GL.Clear(ClearBufferMask.ColorBufferBit); GL.ClearColor(Color4.Red); // Draw traingles GL.EnableVertexAttribArray(0); GL.EnableVertexAttribArray(1); GL.BindVertexArray(vaoID); GL.UseProgram(programID); GL.BindBuffer(BufferTarget.ArrayBuffer, vboID); GL.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, 0, IntPtr.Zero); GL.ActiveTexture(TextureUnit.Texture0); GL.BindTexture(TextureTarget.Texture3D, textureID); GL.BindBuffer(BufferTarget.ElementArrayBuffer, iboID); GL.DrawElements(BeginMode.Triangles, indices.Length, DrawElementsType.UnsignedInt, 0); GL.DisableVertexAttribArray(0); GL.DisableVertexAttribArray(1); SwapBuffers(); } protected override void OnClosed(EventArgs e) { base.OnClosed(e); GL.DeleteVertexArray(vaoID); GL.DeleteBuffer(vboID); } } } I can not remember where do I add GL.Uniform2();
    • By Jens Eckervogt
      Hello everyone
      For @80bserver8 nice job - I have found Google search. How did you port from Javascript WebGL to C# OpenTK.?
      I have been searched Google but it shows f***ing Unity 3D. I really want know how do I understand I want start with OpenTK But I want know where is porting of Javascript and C#?
       
      Thanks!
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OpenGL Skewed/Sheared Texture Mapping in OpenGL

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Hi, I have recently come upon a certain task I need to do for my game. It seemed easy at first, but it turned out to be a bit trickier than I imagined. What I need to do is very simple: I have to render a trapezoid with 3 of the 4 sides at 90 degree angles, except the last one. It has to be correctly textured/gradient filled. Imagine a flat square facing you in 3D space, rotate it a bit, and that's exactly what I need. However, my game is 2D (for the most part) and all the points (including this trapezoid) lie on the z-plane. So what I need is some sort of skewed/sheared (I'm not sure which term correctly describes this) texture mapping (or shading, if I use basic colors and no textures). The most obvious solution to try would be something like this, of course:
glBegin(GL_QUADS);
	glTexCoord2f(0, 0); glVertex2f(0, 0);
	glTexCoord2f(1, 0); glVertex2f(100, 0);
	glTexCoord2f(1, 1); glVertex2f(100, 100);
	glTexCoord2f(0, 1); glVertex2f(0, 100 / 2);
glEnd();
Unfortunately, the quad gets broken down into 2 triangles and the results are not as desired: To be honest, I'm not exactly sure how to properly accomplish something like this in OpenGL. I've tried searching around but didn't really find anything (maybe it's because I don't know the right term for this kind of transformation). Reading the texture mapping section of the red book didn't help either. The only solution I could think of, was to modify the texture matrix to perform this transformation, so something like this:
glMatrixMode(GL_TEXTURE);
glLoadIdentity();
glGetDoublev(GL_TEXTURE_MATRIX, m);
m[0] = 2.0;
m[5] = 2.0;
m[3] = 1.0;
glLoadMatrixd(m);
// Note: glTexCoord2f(0, 1); has to be changed to glTexCoord2f(0, 0.5);
Did the trick. Only thing is, the exact coordinates of my trapezoid will be determined at run time (once per frame), so this matrix would have to be recomputed for every different angle that the top edge makes... This hardly seems like an elegant solution, anyway. I was wondering if anyone could point me towards a better/simpler solution, if there is one. Note that I'm trying to minimize the system requirements, so using shaders for such a simple task, for example, might not be a better solution for me. --- Thanks, shurcooL`

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What you need is perspective correction - this normally involves giving the rasterization system (in this case OpenGL) some kinda perspective matrix in the 3d case and letting it figure out the perspective correct texture mapping itself.

Since you're doing the actual screenspace projection yourself, you need to manually specify the homogenous texture coordinate yourself so that OpenGL knows you need perspective, which is simple via the API:

Simply call glTexCoord4f(s,t,0,q) instead of glTexCoord2f(s,t) and supply the homogeneous coordinate 'q' for the perspective transformation.

Okay, so how do you calculate the 'q', then? Well it turns out that this is easy if you know some information about your perspective transformation. Unfortunately this will be extremely difficult for your case without more information, but I'll explain the theory anyway:

Given a 3d vertex ('x,'y,'z), OpenGL will extend it to a 4d vector: ('x,'y,'z, 1). Given a 2d vertex ('x, 'y), OpenGL will extend it to a 4d vector ('x,'y,0,1)

The view-space vertex (ie. the above 4d coordinate transformed by the modelview matrix) will be be further transformed by the projection matrix (ie. a matrix setup via gluPerspective) to yield (x,y,z,w). In cases where there is no perspective, 'w' will be 1.

The final coordinate that is passed on to be transmitted into window coordinates is (x,y,z,w) multiplied by '1/w'. ie (x/w, y/w, z/w).
(Remember, in cases where there is no perspective, 'w' will be 1 and will yield the original vector (x,y,z) still)

Additionally, the 1/w term is used to perspective-correct the texture coordinate that you have given OpenGL. If you gave (s,t) to OpenGL, the final coordinate that gets passed down the pipeline is also multiplied by 1/w, ie. it will result in the coordinate: (s/w, t/w, 0, 1/w).

Now, your current situation is as follows: your vertex position is already 'perspective-corrected'. Ie you are passing "post-projection" screen coordinates (x,y) to OpenGL, but you are not passing down perspective correctable texture coordinates (ie. ones with a valid 'q' term)

To get the perspective correct texture coordinate you will need the 'w' term for the projected vertex and pass down the (s/w,t/w,0,1/w) instead of the (s,t) that you normally would have.

This is not an easy task in your case - as calculating 'w' is extremely non-trivial without:
1.) a concept of how far each vertex is from the camera/eyepoint.
2.) a projection transformation that would performs the *EXACT SAME* perspective transformation that you used to obtain your already projected screen coordinates.

Sorry to be the bearer of such horrid news, but, for the most part I think you'll find things easier if you just build your quads in 3d and let OpenGL do the perspective calculations for you. Let the API work for you! :)

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